Stg specification

ULTRATECH CEMENT LIMITED, BIRLA WHITE CEMENT - III, KHARIA KHANGAR, JODHPUR,

RAJASTHAN

TENDER DOCUMENT OF 1X21 MW CPP

SECTION 4– TECHNICAL SPECIFICATION

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4.2 DETAILED TECHNICAL SPECIFICATION FOR STEAM TURBINE AND AUXILIARIES

4.2.1 General This section of the technical specification defines minimum technical

requirements for design, manufacturing, supply, installation, erection, testing and commissioning of the steam turbo-generator system with all the accessories and auxiliaries.

4.2.2 Conditions of Service 4.2.2.1 The steam turbo generator will be installed in a separate powerhouse,

along with the entire auxiliary equipment and systems. The Powerhouse will be provided with EOT crane for the maintenance purpose of the turbo generator.

4.2.2.2 The turbine control shall be located in the control room, located

adjacent to the turbo generator, whereas important indicating instruments shall be provided near the turbine in the local gauge board. Emergency stop arrangements shall be provided in the local gauge board.

4.2.3 Design and Engineering 4.2.3.1 The SUPPLIER must offer a very reliable and efficient system with

state-of-the-art proven design with good performance over a long period. The SUPPLIER shall offer the system including (but not limited to) the following design and engineering features:

- Highest possible thermal and energy efficiency. - State-of-the-art technology and well proven in actual operation

over a long period. - Rugged, conservatively designed, proven components and

systems. - Minimum outage for field maintenance and routine inspection. - Better operability at various load conditions. - Advanced instrumentation, control systems, shut-down and

protection system, very reliable online supervisory and surveillance system, with diagnostics.

- Minimum requirement of operating and maintenance man-


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power and amenability to unattended automatic operation. - Suitability for harsh tropical ambient conditions prevailing at

site. - Simple design and ease of installation. The SUPPLIER may incorporate additional features and improvements

to enhance the efficiency and reliability of the system. 4.2.3.2 The turbine shall be horizontal, single cylinder, bleed cum condensing

type. Provision for required numbers of bleed shall be envisaged. The High Pressure (HP) bleed steam will meet the feed water heating requirements in HP feed water heaters. Medium Pressure (MP) bleed steam from the turbine will meet the steam requirements of the de-aerator. The LP bleed steam will meet the LP feed water heater steam requirements. Necessary spray water pressure reducing station and desuperheater, if required in the bleed steam line, shall be provided by the SUPPLIER. The requirement and sizing of the Desuperheating stations in the extraction lines shall be decided based on the possible operation of the turbogenerator from 30 % to 100 % load.

4.2.3.3 All casings and stator blade carriers shall be horizontally split or

otherwise and the design shall be such as to permit examination of the blading without disturbing shaft alignment or causing damage to the blades. The design of the casing and the supports shall be such as to permit free thermal expansion in all directions. The casing shall also permit the inspection of the bearings without dismantling of the casing. The bleed branches shall be located on the lower half of the casing.

The low pressure casing shall have a bottom exhaust arrangement

configuration and the exhaust casing shall be suitable for connection to the condenser without air leakage and suitable for maintaining the condenser vacuum. The turbine exhaust hood shall be provided with exhaust water spray system to protect the turbine against excessive temperature due to windage at no load and low load conditions. The spray system shall be provided with complete spray nozzles, automatic spray control valve, interconnecting piping, all necessary controls, instrumentation and fittings.

4.2.3.4 The turbine shall have solidly forged and machined rotor with integral

disks. The rotor after fully machined and bladed shall be dynamic balanced accurately in the shop and shall be given a overspeed test under vacuum. None of the critical speeds of the rotor shall fall within the range of 20% above and 20% below the normal running speed of the rotor. The SUPPLIER, shall analyze the complete coupled train for both lateral and torsional vibrations, and ensure proper separation


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margins. The rotor shall be designed to withstand the maximum shock loading that may occur during any power system disturbance.

Such shock loading values shall be taken for the design of the gear box

and the generator rotor. SUPPLIER shall specify clearly the construction of the rotor, the heat treatment proposed and the procedure for inspecting the shaft to ensure soundness and homogeneity of the material in the QAP. The material of construction shall be consistent with proven practices and standards.

To bring the turbine rotor from full speed to rest as quickly as possible,

whenever required a vacuum breaker valve capable of being operated remotely from the control room and capable of operating in conjunction with the turbine over speed protection system with necessary interlocks and logics shall be provided. (This valve will be located in the exhaust duct connecting the turbine and the Air cooled condenser). The valve shall have the facility for local manual operation.

4.2.3.5 The blading shall be designed to withstand all vibrations, thermal

shocks, and other loading that may be experienced during service and system disturbances. The blades shall be machined from forged bars or die forged and the materials used shall be chromium steels suitable for the temperatures encountered, resistant against corrosion and erosion and consistent with proven experience and standards. In the low pressure stages, if warranted where the moisture percentage is higher, additional protection against erosion shall be provided.

The blading depending on the staging shall be adequately fastened as

per the standard practice of the SUPPLIER, but such methods of fixing the blades shall be a proven one by long use in operation. The rotating blades are either shrouded or tied with lacing wires depending on the stresses and the excitation frequencies.

4.2.3.6 Gland Sealing System The glands shall preferably be of labyrinth type and sealed with steam.

The gland packing shall be of 13% chromium stainless steel. The labyrinths shall be of multi-section spring backed type which would allow for any temporary deformation of the rotor shaft without overheating the rotor due to friction. Any other sealing system compatible with the operating conditions may also be furnished, but however the details of the offered system shall be furnished by the supplier. The complete piping, valves, pressure gauges, regulators etc. required for the end seals shall be provided by the SUPPLIER. During the normal operation of the turbine the source of sealing steam will be from the turbine. If external sealing steam is required also during the normal running, it should be specified by the supplier. Required gland


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steam condenser with 2 x 100 % capacity AC motor driven exhausters shall be provided. Suction fans, wherever provided shall have one 100 % capacity operating fan and one 100 % capacity standby fan. All piping and components of shaft seal system shall be sized for 150 percent of the calculated new clearance leakages.

The cooling medium shall be the condensate from Air cooled condenser.

The shell side shall be designed for the maximum steam pressure from gland and for full vacuum. The tube side shall be designed for the cold shutoff pressure of the condensate extraction pumps. The gland steam condenser shall be provided with all instruments and accessories including thermal relief valve.

4.2.3.7 Bearings The Turbine shall be provided with liberally rated hydrodynamic radial

and thrust bearings. The radial bearings shall be split for ease of assembly, and of the sleeve or pad type, with steel shell backed, babbitted replaceable pads. These bearings shall be equipped with anti rotation pins and shall be positively secured in the axial direction. The thrust bearings shall be of, Mitchell tilting pad type, the steel backed babbitted multiple segment, designed for equal thrust capacity in both directions. A liberal flow of lube oil under pressure shall be supplied to all the bearings for lubrication and cooling.

All bearings shall be accessible without having to remove cylinder

covers. The metal temperatures of all the bearings shall be monitored by thermocouples with extension right into the white metal layer. Provision shall be made for measuring the temperature of the oil leaving the bearings.

4.2.3.8 Lubrication and control oil system 4.2.3.8.1 A pressure lubrication and control oil system shall be furnished for the

turbo generator unit to supply oil at the required pressure to the steam turbine, gear box, generator and governing system. The lubrication oil system shall supply oil to the turbine generator under all the load conditions, including the turning gear operation. The oil system of the turbo generator shall be designed with adequate redundancy and emergency provisions such that a failure of a single active component will not prevent the safe operation or a safe shutdown of the turbo generator. Oil in the reservoir shall be maintained at an appropriate temperature when the TG set is idle by providing suitable electric heaters and temperature controls if required.

For the hottest ambient conditions to be encountered at the site the oil

outlet temperature at any bearing shall neither exceed the maximum


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permissible temperature for the bearing metal nor the maximum safe operational temperature of the oil.

4.2.3.8.2 The oil system shall include the following:

- One hundred percent (100 %) capacity centrifugal type AC driven Main oil pump

- One (1) No. of one hundred (100 %) capacity A.C motor driven

auxiliary oil pump of centrifugal type, arranged to cut in automatically if the oil pressure falls to a preset value. This pump shall also meet the requirements during the start up and shutdown.

- One (1) D.C motor driven, centrifugal type, emergency oil pump of

adequate capacity to provide adequate lubrication in the event of a failure of the A.C motor driven pump(s). This pump also shall cut in automatically at a pre set value of the oil pressure. The minimum capacity of this pump shall be to ensure a safe shutdown of the turbogenerator.

- 2 x 100% (1AC+1DC) Jacking oil pump with all piping, valves,

instruments, etc. - Two 100 % capacity (one working and one standby) water cooled

oil coolers. - Two 100 % duty oil filters arranged in such a way that it is possible

to clean one oil filter while the other is in service. The filters and the coolers shall be arranged with continuous flow transfer valves.

- Oil storage and settling tank with adequate reservoir capacity,

strainers, level indicators with float switches and alarm contacts, vent and oil mist eliminators and 2x100% capacity vapour exhaust fans.

- Flow and temperature indication for oil from every bearing. - LVDH for oil purification including interconnecting piping and valves. - Oil clarification system (ELC machine of 100 LPH capacity) - Emergency gravity lube system designed for lubrication up to

coasting down period of turbine & additional margin in overhead tank to address the emergency in case of delay in EOP start up

- Collecting oil tank with oil transfer pump. The oil from the collecting

oil tank will be pumped to the main oil tank, upstream of the inlet


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strainer. Collecting oil tank capacity shall be the same as Main oil tank.

If the system envisages separate control oil circuit from the lube oil system, there shall be independent two nos. of control oil pumps and 2 x 100 % duplex oil filters for the control oil circuit.

The Main and Auxiliary oil pumps and the emergency oil pumps shall be

arranged to have flooded suction. Supply of the flushing oil and the first fill up of lube oil for the turbine

and accessories shall be the responsibility of the SUPPLIER and preferably from the Indian market.

4.2.3.8.3 Oil coolers The oil coolers shall be water cooled with a duplex arrangement and

changeover valves. The coolers shall be of shell and tube type with removable tube bundle. The tube material shall be SS304. The coolers shall be constructed in accordance with TEMA class C. The provided surface area shall be adequate to cool the oil with inlet cooling water even with the indicated percentage of the tubes plugged (margin specified else where in the tender specification). The coolers shall be amenable for easy inspection and maintenance and cleaning of one cooler while the other one is in service shall be possible. The oil cooler shell side shall be designed for cold shut off head of the oil pump and tube side shall be designed for a pressure of 6 kg/cm² (g). Necessary lifting lugs shall be provided. There shall be isolating valves on either side of the oil coolers (Upstream insolating v/v shall gate v/v and down stream v/v shall be glove v/v) in cooling water line.

4.2.3.8.4 Filters Full flow twin oil filters shall be used, for the lube oil, downstream of

the coolers and shall be piped in a parallel arrangement with a continuous flow transfer valve. Filter cartridges shall have a minimum collapsing differential pressure of 3.5 kg/cm². The minimum design pressure for the filters shall be the maximum discharge pressure of the oil pumps. Differential pressure gauge with alarm shall be provided across the filters. The filters shall be either common or separate for the lube and control oil circuits.

Oil filters shall be arranged in such a way that it is possible to clean one

oil filter while the other is in service. The filters and the coolers shall be arranged with continuous flow transfer valves. The filter grade for the control oil shall be 10 Microns nominal. If a common filter is used for lube and control oil, the filter grade shall be 10 microns nominal.


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4.2.3.8.5 Oil reservoir The interior of oil reservoirs shall be desalted and rust proofed with a

permanent coating. Reservoirs with top mounted equipment shall have sufficient rigidity. The cover plate shall be adequately stiffened to carry the load. All openings for piping shall be made dust and water proof. The oil reservoir shall be so located to permit draining of the contents by gravity and shall be equipped with fine and coarse mesh strainers. The oil drained shall be collected in a drain oil tank/collecting tank of suitable capacity located on the ground floor of the TG building and two numbers of drain oil pumps shall be provided to pump the oil back to the oil reservoir (in case of overflow from the oil reservoir) to outside the TG building for disposal.

The reservoir shall be of adequate capacity. The reservoir shall be

provided with 2x100 % oil vapour extractors, with oil separator, for proper ventilation. All necessary piping connections, valves and fittings, level switches and level gauges shall be provided. Corrosion allowance of 3 mm shall be considered while designing the system.

All necessary piping, valves and fittings shall be provided for the

complete oil system shall be provided by the SUPPLIER. The complete piping shall meet the requirements of API 614. The flanges provided in the stainless steel oil lines downstream of oil filter shall be LJFF type if the flange is of carbon steel material or SORF if the flange is of stainless steel material. If stainless steel material is used they shall confirm to SA 182 F 304 specification.

4.2.3.8.6 Oil purifier and ELC Machine A centrifugal type oil purifier shall be provided for the removal of water,

sediments and other oxidation products from the Lube oil system on a continuous basis. The purifier shall be a separate complete package, mounted on a skid, complete by itself with drive motor, piping, valves and fittings. Feed to the purifier shall be from the drain end of the reservoir and its operation shall be independent of the oil system.

In Addition to the above Electrostatic liquid cleaner machine of 100 LPH

shall be provided. 4.2.3.8.7 Emergency Oil Tank Emergency gravity lubricating system shall be provided to assure the

lubrication at the time of emergency due to the failure of the DC operated lube oil pump. This system shall draw lube oil from an overhead tank, under gravity, and shall be designed to supply oil for the coasting down period of the machine.


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The overhead tank shall be SS and the complete piping shall be of SS 304 material. The tank elevation shall be finalized based on the oil pressure requirements at the bearings.

The system shall be designed with continuous overflow circulation of oil

to avoid sludge formation in the tank. The Vent / overflow of the emergency overhead oil tank shall be brought down to the oil reservoir or to the collecting tank, if a separate tank is provided for collecting the oil overflow from the emergency oil tank. This is required to ensure that there is no dust ingress into the oil system while the oil is drained from the emergency oil tank.

4.2.3.8.8 Collecting/ Settling oil tank The settling oil tank shall be located on the ground floor for draining the

oil from the oil coolers, oil filters and generally from the piping and equipment of the oil system. The drain lines shall be of carbon steel and shall be routed from the respective equipment and other draining points to the tank. The tank shall be epoxy coated on the inside. There shall be two transfer pump, gear or centrifugal type, for the transfer of the oil from the settling tank to the main oil tank.

4.2.3.9 Steam Turbine Governing System The turbine governing system shall be electro-hydraulic designed for

high accuracy, speed and sensitivity of response. The electrical/ electronic and hydraulic components of the control system shall be selected on the basis of reliability over a wide range of operating conditions. All components used shall be well proven to assure overall system reliability and shall be designed for easy and quick replacement when necessary. The governor shall be configurable in the field.

The governor shall ensure controlled acceleration of the turbo generator

and shall prevent over speed without tripping the unit under any operating condition or in the event of maximum load rejection. The governor shall have linear droop characteristics with a suitable range for stable operation and shall have provision for adjusting the droop in fine steps.

The governing system shall have the following important functions: - Speed control - Over speed control - Load control - Inlet Steam pressure control The governor shall be configured to incorporate the following controls

while operating in parallel with the grid:


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a. Load set point shall remain unaffected for the variation of frequency between 47.5 Hz and 52.5 Hz

b. The turbine inlet steam pressure shall be maintained at the set

value by controlling the power export to the grid. 4.2.3.10 External Forces and Moments The SUPPLIER shall furnish the allowable forces and moments on the

turbine nozzles. As a minimum requirement the turbine shall be designed to withstand the external forces and moments calculated in accordance with the requirements of NEMA SM 23. The SUPPLIER shall also furnish the thermal expansion movements on each of the nozzles in the turbine.

4.2.3.11 Thermal Insulation and Lagging The steam turbine and the other high temperature parts, including

piping supplied, shall be insulated with low conductivity inert material, where required, reinforced by stainless steel wire net between applied layers. The insulation shall be so arranged that it can be removed for access to the flange bolting, control valves and other parts that require periodic maintenance. The insulation shall be designed, such that the outer surface temperature of the insulation does not exceed 20 Deg. C above the ambient temperature.

For turbine casing only glass fiber insulation removable pads shall be

considered, with surface cladding with suitable material. Pre molded pipe section insulation of glass fiber material shall be

considered for turbine Steam pressure cycle with aluminum cladding of material code L 100 & L150

4.2.4 Capacity and Performance Requirement 4.2.4.1 Turbine Generator Rating The turbine rating and other performance criteria shall be as specified in

the section on Performance Guarantee. 4.2.4.2 Bleeds The turbine shall be provided with required number of bleeds, as

mentioned elsewhere in the specification. 4.2.4.3 Economic Load


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The specific steam consumption shall be the lowest for operating loads between 80 to 100%.

4.2.4.4 Over Loading The system offered shall be suitable for an overload specified in the

specification on continuous basis. 4.2.4.5 No load and Minimum load operation The turbine shall be capable of operating under no load condition

during loss of load for a maximum period of 60 minutes. The minimum load at which the turbine is required to operate continuously shall be 15% of the designed capacity.

4.2.4.6 Specific steam consumption This guaranteed specific steam consumption / heat rate shall be for the

economic load and the testing shall be as per IEC Recommendations Publication 46.

4.2.4.7 Governing Characteristics When the machine is operating with rated steam conditions and at

rated speed, and the maximum load is thrown of, the operation of the electronic speed governor shall prevent the speed rising to a value at which the over-speed trip is set to operate. The speed governor droop, i.e. permanent speed variation from no load to rated output etc., shall be within the limits specified in IEC Recommendations Publication 45.

4.2.4.8 Parallel operation The characteristics of the turbine shall be such that the turbine

generator set can be run in parallel with the State power grid and / or with the machine to be added later on and possess no abnormal features either individually or collectively.

4.2.4.9 Speed adjustment The turbine speed at no load shall be adjustable between 6% below

and 6% above rated speed. Means are to be provided whereby the speed of the turbine at no load can be raised in a controlled manner for the purpose of testing the over speed trip mechanism and provision made to ensure that such means do not interfere with the action of the speed governor in normal operation. The device to raise speed at no load must incorporate limiting means to prevent it from reaching a dangerous speed.


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4.2.4.10 Over speed trip

In addition to the speed governor and electronic over speed relay with 02 of 03 logic (wood word make Protec 203), the turbine and generator shall be protected against excessive overspeed by a separately actuated (Mechanical trip device) overspeed device which operates the trip system. In the event of sudden load rejection, should the speed governor fail to meet the requirements the overspeed trip shall operate to prevent any damage. The overspeed trip setting shall be stated by the SUPPLIER in the operating instructions. The over speed trip mechanism shall be capable of being reset when the speed of the tur-bine has decreased to a speed not lower than the rated speed.

4.2.4.11 Trip system

The turbine shall be provided with a trip system for the complete and rapid closure of steam valves effectively preventing all steam admission to the turbine independently of the closure of the governing valves. In order to avoid sudden re-admission of steam to the turbine the trip system shall be fitted with interlocking devices so that trip resetting cannot take place until steam admission can only be achieved as per normal starting up procedure. Essential trip circuits to be provided are:

- Steam inlet pressure falling below pre-determined level. - Steam temperature falling below pre-determined level. - Steam inlet pressure raising above pre-determined level. - Steam temperature raising above pre-determined level. - Excessive wheel chamber pressure. - Turbine differential casing expansion. - Condenser vacuum falling below pre-determined level. - Lubricating oil pressure falling below pre-determined level. - Axial thrust wear trip. - High temperature trip for LP stage steam flow. - High turbine bearing vibration. - High turbine bearing temperature. - Low control oil pressure. 4.2.4.12 Maximum speed An overspeed test of the turbine rotor shall be carried out preferably at

the SUPPLIER's works. The overspeed tests shall be at a speed exceeding by 2% the maximum calculated overspeed that would occur if the speed governor failed and if the maximum overspeed was limited by the action of the overspeed trip device only. The duration of the over speed test shall be less than 2 minutes. The overspeed shall not be more than 20% of the rated speed. Supplier shall indicate all over speed trip set point.


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4.2.4.13 Vibration The foremost in the Turbine Supervisory Instrumentation system is the

vibration measurement which provides the basic protection to the Turbogenerator. The system of vibration measurement shall include shaft radial vibrations at the radial bearings, axial displacement and thrust position, Speed and differential Expansions. The shaft radial vibration measurement shall employ proximity probes in the X-Y configuration in two orthogonal directions in each bearing. For the measurement of the thrust position two proximity probes shall be employed in a dual voting arrangement.

Vibration measuring and monitoring systems of reputed make (Bently Nevada make of the latest 3500 series system is preferred) shall be provided for measuring the shaft vibration of turbine, gearbox and generator. All the bearings of the turbine, gear box and generator shall be provided with the probes for measurement. The maximum allowable vibration under any specified operating conditions shall be indicated by the SUPPLIER. The detailed specification is indicated in Instrumentation section.

4.2.4.14 Critical speed The critical speed for the combined turbine and generator train shall be

sufficiently away from the rated speed to avoid any adverse effect on the operation of the unit over the range of operating speeds.

4.2.4.15 Hydraulic test All parts subjected to steam pressure shall be tested hydraulically for a

pressure of 1.5 times the working pressure. For those parts which are made of materials which may be damaged by such tests the test pressure shall be agreed by the OWNER and the SUPPLIER during tender stage.

4.2.4.16 Materials of construction The selection of materials for parts of the machine shall be based on

the experience of the SUPPLIER and experimentally determined data and shall conform that under conditions of stress, temperature and time the components will not fracture or deform to a greater extent than is permissible. The materials selected shall be clearly indicated in the turbine and auxiliaries data sheets.

4.2.4.17 Variation of steam pressure and turbine The turbine shall be capable of accepting variations from the rated

conditions within the limits specified by IEC Recommendation


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Publication 45 except inlet high high pressure trip. 4.2.4.18 Limit of lubricating oil temperature The SUPPLIER shall furnish the permissible temperature for the

bearing metal. 4.2.4.19 Noise The turbine and gear box shall be provided with acoustic enclosure to

reduce the noise level to the specified limits of 80 dB (A) at 1 m distance from the equipment. Acoustic enclosure should include fire protection & fire alarm system with sufficient movable path inside the enclosure.

Measurement shall be made with the machine running under normal

operating conditions at not less than 8 points evenly spaced around the machine and auxiliaries, approx, 1 meter from the periphery and at the heights of the center lines of main and auxiliary machines.

Noise measurements shall also be made during running tests in

SUPPLIER’s works so that any corrective action, which appears to be necessary, can be carried out in advance of operation at site.

4.2.5 Safety 4.2.5.1 All controls shall operate in a fail safe mode. 4.2.5.2 All coupling and gears shall be provided with adequate guards. 4.2.5.3 Piping shall be arranged in such a manner as to avoid tripping or

overhead problems. Piping or tubing of insufficient mechanical strength which is standing or hanging shall be protected from personnel traffic.

4.2.5.4 Surface temperature on any point shall not exceed 60 Deg C. 4.2.5.5 Very high standard of safety shall be built into the set with high degree

of redundancy. 4.2.6 Gearing 4.2.6.1 Gear Box The gear and pinion teeth shall be case carburized and ground to an

accuracy class of 4 or higher to DIN Standards. The hardness of the teeth shall not be less than 58 in the Rockwell Hardness Scale. The overlap ratio shall be adequate to ensure a quiet operation. The gears


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shall be dynamically balanced before assembly. A turbine directly driving the alternator with out a gear box in between

is also acceptable. The gear box shall be capable of transmitting the maximum rating of

the set and be able to withstand 20% overspeed over a period of minimum five (5) minutes. The gear box shall also be designed for the short circuit condition of the generator. All bearings of the gear box shall be readily renewable and shall be possible to inspect the bearings and the gears readily without disturbing the shaft alignment. Illuminated sight glasses shall be provided to inspect the lube oil drain from each individual bearing. The gear box design shall be as per the requirements of AGMA with service factor of 1.6.

The flexible couplings between the turbine and the gear box and

between the gear box and the generator shall be of reputed make. The power rating of the coupling shall be at least equal to the turbine rated power times the service factor in accordance with AGMA 514. Easily removable coupling guard shall be placed over each of the exposed coupling. Easily removable coupling guard shall be placed over each of the exposed coupling. Couplings shall be designed to allow for removal of any rotor without opening adjacent turbine casings. The housing shall be provided with breather.

4.2.6.2 Barring Gear

The turbine shall be provided with a barring gear of mechanical type driven by an A.C motor, to rotate the turbine and generator after shutdown to prevent thermal distortion of the rotor. The barring gear shall be capable of starting the rotor from rest and run it continuously at low speeds. The barring gear shall be interlocked with the lubrication system to prevent its operation without lubrication.

The system shall be capable of Auto & Manual engagement and au-tomatic disengagement when the turbine speed goes above the normal barring gear speed. The system shall also have facility for manual turning in case of A.C supply failure. The turbine panel shall be provided with necessary push buttons, alarms and switches for the operation of the barring gear.

4.2.7 Base Frame Suitable base frame either common or individual shall be provided for

the turbine, generator and the gear box. Provisions shall be made to level each piece of equipment separately. The leveling pads shall be accessible for field leveling after installations with the equipment mounted and the base plate on the foundation.


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4.2.8 Turbine Starting Time The turbine shall have the following starting time from stand still to full

load: Cold start 90 Minutes Hot Start after 8 Hrs Shutdown 20 Minutes 4.2.9 Turbine external piping The turbine external piping shall include the piping and its accessories

as indicated in this tender document. 4.2.10 Piping, Valves and Specialties 4.2.10.1 General The scope of work covered by this specification includes design,

engineering, supply, fabrication, delivery, unloading, handling at site, erection, cleaning, testing, painting and commissioning of all piping system complete with accessories within the terminal points indicated elsewhere in the specification. The piping provided shall be complete in all respects including valves, specialties, supports, thermal insulation etc. as required.

4.2.10.1.1 The flow diagrams enclosed in the tender document are only intended

to indicate the general scope and nature of work to be carried out and do not indicate the exact quantum of work to be carried out by the SUPPLIER.

4.2.10.2 Scope of Supply 4.2.10.2.1 For all the piping systems included in SUPPLIER’S scope of supply

shall include but not limited to: a. Pipes, Tubes, Headers and Manifolds. b. Bends, Elbows, Returns, Tees, Laterals, Crosses, Reduces,

Caps and Closures, Full & Half Couplings, Plugs, Sleeves & Saddles, Stubs & Bosses, Reinforcement pads, Unions, Weldolets, Sockolets, Threadolets and other similar fittings.

c. Valves d. Flanges, Gaskets and Fasteners. e. Complete assemblies of supports, anchors, guides, restraints


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etc, including welded attachments etc. f. Auxiliary Steel, Concrete Foundations, Pedestals etc. as

required for Hangers, Supports, Guides, Restraints, Anchors etc.

g. All Paints, Varnishes, Primers, Thinners and other Painting

Materials. h. Weather hoods for Pipes, Crossing Ceilings and Walls. i. All instrument impulse piping and fittings upto the last root

valve j. In case of temperature measurement points, SUPPLIER’S

scope includes the supply of thermowell stubs with plugs. k. All approach platforms for all valves & instrument shall be

provided with proper stair case (Cage ladder shall not be used).

4.2.10.2.2 SUPPLIER shall supply all necessary drains and vents including anti-

flash funnels as required for the safe and effective draining / venting of the piping systems. It must be noted that the flow diagrams may not indicate all the drains and vents that would be required. It is SUPPLIER's responsibility to identify the requirements of drains and vent whether the same have been shown in the flow diagrams or not and supply the necessary pipework, fittings, hangers and supports etc. The drains and vents indicated on the flow diagrams shall however be regarded as minimum requirements. The drains and vents shall be led upto the nearest floor drain in case of cold water systems and upto the flash tank in case of steam and hot water systems, all as erected by the Supplier.

4.2.10.2.3 Wherever uninsulated pipes cross walls or roofs, the necessary weather

hoods shall be supplied by the SUPPLIER as directed by OWNER. Where required, SUPPLIER shall make openings in floors, walls, gratings etc. for routing the pipes and provide proper finishing after piping is erected.

4.2.10.3 Design Requirements 4.2.10.3.1 The equipment and work under this specification shall conform to the

following standards / codes: a. Indian Boiler Regulations. b. Indian Regulations of Inspector of Explosives.


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c. Applicable Standards for Structural Steel. i. IS:800 : Codes of Practice for use of Structural Steel in general Building Construction. ii. IS:2062: Structural Steel (Fusion Welding Quality) d. American National Standard ASME code for “Power Piping " -

ASME B 31.1 and all other associated ASME Standards. e. Manufacturer's Standardization Society (MSS) USA Standard

Practices. f. American Society of Testing and Materials (ASTM)

Specifications. g. American Society of Mechanical Engineers (ASME) Codes. h. Pipe Fabrication Institute (PFI) USA, Standards. i. American Petroleum Institute Standards (API). 4.2.10.3.2 While routing piping, the following requirements shall be taken into

account by the SUPPLIER: 4.2.10.3.3 All piping shall be routed so as to avoid interference with other pipes

and their hangers and supports, electrical cable trays, ventilation ducting, structural members, equipment etc. Adequate clearances shall be ensured with respect to the above to accommodate insulation and pipe movements.

4.2.10.3.4 All piping shall be grouped where practicable and shall be routed to

present a neat appearance. 4.2.10.3.5 The piping shall be arranged to provide clearance for the removal of

equipment requiring maintenance and for easy access to valves and other piping accessories required for operation and maintenance.

4.2.10.3.6 Piping shall generally be routed above ground but where specifically

indicated / approved by the CONSULTANT, the pipes may be arranged in trenches or buried. Pipes at working temperatures above the ambient shall however not be buried.

4.2.10.3.7 Wherever pipes are to be bent, the bends shall be free from wrinkles

and bulges. The bends shall be made by cold bending. 4.2.10.3.8 Overhead piping shall have a minimum vertical clearance of 2.3 meters

above walkways and working areas and 8 meters above roadways unless otherwise approved by the CONSULTANT.

4.2.10.3.9 Drains shall be provided at all low points and vent at all high points as

per actual layout regardless of whether the same have been shown in the flow diagrams or not. Pipelines shall be sloped towards the drain


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points. 4.2.10.3.10 Provision shall be made while preparing piping layout to accept control

valves, flow measuring elements and any other on line speciality or equipment supplied by others. Sufficient upstream and down stream lengths shall be provided for flow measuring devices, control valves, desuperheaters and other specialities as required by the Suppliers.

4.2.10.3.11 At all screwed valves and screwed connections on equipment, unions

shall be provided to facilitate disassembly. Likewise, unions shall also be provided at suitable points on straight lengths of screwed pipelines.

4.2.10.3.12 All local instruments shall be located on pipelines as to render them

observable from the nearest available platforms and accessible for maintenance.

4.2.10.3.13 Piping with operating temperatures above or below the ambient shall be

routed so as to provide adequate flexibility for the pipes. 4.2.10.3.14 Tap-off on main lines for field routed pipework, if not indicated on

OWNER's layout drawings, shall be suitably located by SUPPLIER to suit the layout evolved by him.

4.2.10.3.15 All steam tracer lines shall be provided with expansion loops to take

care of differential expansion between the tracer and main line. 4.2.10.3.16 Stubs for instrumentation, drains, vents etc. wherever not located on

OWNER's piping layout drawings shall be suitably located by SUPPLIER in accordance with the flow diagrams and layouts.

4.2.10.3.17 At all intersection joints, it is SUPPLIER's responsibility to design and

provide suitable reinforcements as per the applicable codes and standards.

4.2.10.3.18 SUPPLIER is responsible for the complete design and engineering of

all supports, guides, restraints and anchors as required for the piping systems erected by him. SUPPLIER's scope of work shall include but not be limited to the location of all required hangers, supports, anchors, restraints etc. and the design and detailed engineering of individual components of the assemblies as also all associated steel work, concrete pedestals, foundations, welded attachments to piping etc. which form a part of hanger / support system. While the designs shall conform to applicable codes and standards and shall be consistent with inter national practice. Information contained in OWNER's drawings regarding support location, type and detail etc. may be used for guidance. This does not however relieve the SUPPLIER of his responsibility for the design and engineering of the support system.


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4.2.10.3.19 The design and engineering of all temporary pipe work as required for erection, cleaning, flushing, blowing out, testing and commissioning of the piping systems installed by the SUPPLIER is the responsibility of the SUPPLIER.

4.2.10.3.20 Pipelines of NB 40 size and below are regarded as field run piping. It is

SUPPLIER’s responsibility to plan suitable layouts for these systems in- site as per the requirements of this specification and in consultation with OWNER and/ or CONSULTANT. SUPPLIER shall prepare isometric drawings indicating the layout of field run pipe work.

4.2.10.3.21 The SUPPLIER shall design and prepare all fabrication isometric

drawings for all IBR piping and NB 50 and above Non-IBR piping. SUPPLIER shall also submit orthographic drawing with Bill of Material for Non-IBR piping of size NB 40 and below.

4.2.10.3.22 The SUPPLIER shall ensure that the design and reinforcement for

branches shall be calculated as per ASME B 31.1 and in addition, it has to be checked for statutory requirement of Indian Boiler Regulations. For piping reinforcement regulation 362 shall be used. The SUPPLIER shall furnish the calculations for reinforcement for nozzle openings and calculations for welded attachments carried out on the piping.

4.2.10.3.23 In case of branch welding for temperature above 250 deg C, no pad

shall be used for pressure reinforcement and external reinforcement. Also the specific local stress calculation for safety valve stubs, anchor stubs, etc for external loading shall be included as per ASME/ IBR to be included.

4.2.10.3.24 All pipe to pipe joints shall be by butt welding only and no couplings

shall be used. 4.2.10.3.25 All flanges of pressure class 300 and less than 900 shall be of weld neck

type. For class 900 and above the flanges shall be WNRTJ type. 4.2.10.3.26 Pipe fittings like elbows, equal tees and reducers shall be as given

below: a) For pipe size 65 NB and above shall be butt welded type. b) For 50 NB and below shall be socket welded type. 4.2.10.3.27 Branch connections: Equal Branch: a) NB 65 & Above - BW equal tee as per ASME B 16.9 b) NB 50 & Below - SW equal tee as per ASME B 16.11


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Unequal Branch:

a. Branch up to NB 50 SW half coupling as per ASME B 16.11 to be used, for run pipe size NB 65 and above.

b. Branch NB 65 and above, branch piping with suitable

reinforcement shall be used. However no reinforcement pads shall be used for applications with design temperature exceeding 300 Deg.C.

c. Equal tee with reducing coupling or reducer to be used for run

size NB 50 and below. d. No branch welding shall be used for equal branch, and only

tees as per ASME B 16.9 or ASME B 16.11 to be used. 4.2.10.3.28 All pressure tappings for pressure applications above 40 Kg/Sq.Cm

shall be of size NB 25 with two root valves. For pressures 40 Kg/Sq.Cm and less the size shall be NB 15 with one root valve. For temperature above 400°C irrespective of pressures, the root valve size shall be NB 25.

4.2.10.3.29 All thermowell boss shall be one (1) inch NPT. 4.2.10.3.30 Pipe Sizing and Layout 4.2.10.3.30.1 The design of the piping system shall be based on the ASME B31.1

code. In addition the statutory requirements of the IBR shall also be taken care of wherever required. Flexibility analysis shall be made for all piping systems with operating temperatures above 100 Deg.C. The correct locations of hangers and supports, with as applicable spring stiffnesses, shall be considered for the flexibility analysis. Suitable expansion loops, restraints and anchors shall be provided so as to ensure compliance with the applicable codes and to limit the stress and reactions to within the allowable values.

4.2.10.3.30.2 All piping shall be sized considering the allowable velocity and

allowable pressure drop in the system. The indicative flow velocities in pipes shall be limited to the following values. However, if the available pressure drop is to be maintained, the piping system may have to be selected even with a lower velocity than the minimum indicated.


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Allowable velocities for sizing of pipes

Nominal pipe size Average velocity in Meter / Second In mm Below 50 mm 50 to 150mm 200 mm &

above Saturated steam at sub atmospheric pressure

- 10 - 15 15 - 20

Saturated steam at 0-1 kg/sq.cm.(g)

15 - 20 17 - 30 20 - 30

Saturated steam at 1.1 - 7 kg/sq.cm.(g)

15 - 22 20 - 33 25 - 43

Saturated steam over 7 kg/sq.cm.(g)

15 - 25 20 - 35 30 - 50

Superheated steam at 0 – 7 kg/sq.cm.(g)

20 - 30 25 - 40 30 - 50

Superheated steam at

7.1 – 35 kg/sq.cm.(g)

20 - 33 28 - 43 35 - 55

Superheated steam at 35.1 - 70 kg/sq.cm.(g)

22 - 33 30 - 50 40 - 61

Superheated steam over 70 kg/sq.cm.(g)

22 - 35 35 - 61 50 - 76

Compressed air 7 – 10 10 -15 18 Pump suction, condensate - 0.4 - 0.6 0.6 - 0.7 Pump suction, boiler feed - 0.6 - 0.9 0.6 - 0.9 Pump suction, general service 0.6 - 0.9 0.7 - 1.3 0.9 - 1.5 Pump suction, viscous liquid 0.3 0.3 - 0.4 0.4 - 0.5 Pump discharge, condensate 0.9 - 1.2 1.2 - 2.1 1.5 - 2.2 Pump discharge, boiler feed 1.0 - 1.2 1.5 - 2.1 1.8 - 2.4 Pump discharge, general service 0.9 - 1.0 1.5 - 2.4 1.5 - 2.4 Pump discharge, viscous liquid 1.0 1.0 1.2 - 1.4 Header, general service under 2.0 kg/sq.cm.(g)

- 1.3 - 2.0 1.8 - 2.4

Header, general service 2.0 kg/sq.cm.(g) & up

- 1.5 - 2.4 2.1 - 2.4

Note : The above velocity values are indicative and showing the maximum

limits of the flow velocity. Lower velocities may be selected if found necessary to meet the allowable pressure drop across the pipes.

4.2.10.3.30.3 Drains at all low points and vents at all high points shall be provided. 4.2.10.3.30.4 All local instruments shall be located on pipelines so as to render them

observable from the nearest available platform. 4.2.10.3.30.5 All pipes of size NB 50 & below shall be schedule 80 thickness for all


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applications.

4.2.10.4 Materials 4.2.10.4.1 Pipe materials for various services and materials for fittings, flanges,

fasteners shall not be inferior to the specifications given below. All piping except, for cooling water, raw water, safety and relief valve exhausts, vents and air services shall be of seamless steel. For cooling water, raw water and air services the piping could be of ERW.

4.2.10.4.2 Piping for services with metal temperatures equal to or greater

than 400 Deg.C and less than 510 Deg.C, 1 1/4% chromium, 1/2% molybdenum ferritic alloy steel seamless pipe as per ASTM A-335 P-11 or P12. Piping for services with metal temperatures higher than 510 Deg.C shall conform to the specifications of ASTM A-335 P22 (2 ¼ chromium 1 molybdenum steel) or its equivalent.

4.2.10.4.3 Piping for services at temperatures less than 400 Deg.C for steam,

boiler feed, condensate, drain piping etc., carbon steel piping as per ASTM A-106 Grade B.

4.2.10.4.4 HP and LP chemical dosing system: Stainless Steel to SA 312 TP 304

specifications. 4.2.10.4.5 Other Services: Carbon Steel Piping as per ASTM A-106 Grade B. 4.2.10.4.6 For the safety valve exhaust piping, where the exhaust steam

temperature is less than 400 Deg.C, the piping material shall be IS 1239 Black Heavy Class for size upto NB 150 and as per IS 3589 for size NB 200 and above.

4.2.10.4.7 For cooling water and raw water applications the piping material shall

be IS 1239 Black Heavy Class for size upto NB 150 and as per IS 3589 for size NB 200 and above.

4.2.10.4.8 For Service air applications the piping shall be GI pipes IS 1239. 4.2.10.4.9 For instrument air applications: IS 1239 GI pipes. 4.2.10.4.10 For piping system where IS1239 or 3589 pipes are used, the fittings

shall be as per A 234 as per ASME B 16.9 and ASME B16.11. All flanges shall be as per ASME 16.5.

4.2.10.4.11 All materials shall be certified by proper material test certificates. All

material test certificates shall carry proper heat number or other acceptable references to enable identification of the certificate with


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the material it purpose to certify. The heat number shall also be indi-cated on the material certified.

4.2.10.5 Fabrication and erection 4.2.10.5.1 Pipelines NB 50 mm and above size are deemed prefabricated.

SUPPLIER shall prepare necessary fabrication isometric drawings. SUPPLIER's fabrication drawings shall take into account the requirements of these specifications as also all applicable codes and standards including statutory regulations such as Indian Boiler Regulations. Fabrication and erection of piping systems NB 50 mm and above size shall be as per SUPPLIER’s fabrication drawings. In case of systems requiring statutory clearance, fabrication and erection shall commence only after the necessary clearance have been obtained from the statutory authorities. SUPPLIER's fabrication drawings including isometrics, if required, shall carry all details of fabrication, welding etc. as may be required for obtaining the necessary statutory clearances.

4.2.10.5.2 Piping NB 50 mm and above size shall be fully fabricated at

SUPPLIER's Works which shall be adequately equipped with the required machinery, templates, gauges, tools and tackles etc. Suppliers shall provide the details of the facilities available at their works for fabrication of pipe work. The extent of fabrication at works shall be such as to restrict field welding to circumferential line joints alone. Further, the number of circumferential line joints to be performed in the field shall be held to a minimum, limited by transport considerations and erection constraints.

4.2.10.5.3 Pipelines having size NB 40 mm and below are deemed field run and

are hence fabricated in site. For bends, only socket weld elbows to be used.

4.2.10.5.4 All welded attachments on pipelines shall be of same material as the

parent pipeline and shall be subjected to the same fabrication and welding procedures as the associated piping.

4.2.10.5.5 The use of companion flanges to connect two pieces of pipe and the

use of odd or short pieces of pipe in making up long runs is prohibited except as noted on OWNER's piping drawings.

4.2.10.5.6 Where welded pipe or fittings are used, longitudinal welds in adjoining sections shall be staggered to a minimum of 90 degrees during fabrication. All piping shall be fabricated true to lines and elevations as indicated on the piping drawings.

4.2.10.5.7 Bends in seam welded pipe shall be oriented so that the seam is positioned along the neutral axis.


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4.2.10.5.8 No welding shall be carried out on lined pipes.

4.2.10.5.9 Gas cutting for bolt holes including for U-clamp supports shall be prohibited.

4.2.10.5.10 Cutting of standard elbows to odd angles as required per layouts, is included in SUPPLIERS's scope.

4.2.10.5.11 Neither butt nor branch joints shall be closer than twice the pipe diameter to any other joint in the same pipe except where "weldolet" type fittings are used in which case the branch weld must be made to the "weldolet".

4.2.10.5.12 All pipe bends, where the pipe diameter is NB 65 and above, shall have a radius of five nominal pipe diameters unless otherwise specified on the OWNER's piping drawings. The pipe bends shall be true to angle and radius and shall maintain a true circular cross section of pipe without deformity or undue stretching. Crimping of pipes to form bends is not acceptable. Only cold bending which does not require stress relieving operation may be carried out at site. Any bending requiring preheating has to be done only at shop. Cold bending shall be done using pipe bending machine (manual or electric). Bends shall be free from wrinkles and bulges.

4.2.10.5.13 All welded branch connections shall be of suitable structural adequacy

by virtue of the intrinsic weld connection, reinforcing plates or rings or material inherent in the branch. It is the SUPPLIER’s responsibility to provide reinforcement wherever necessary for branch connections. Welded branch connections are not an acceptable alternative where tees have been specified.

4.2.10.5.14 All threads on piping components shall be taper pipe threads as per

applicable standards. The nipples shall be fabricated by the SUPPLIER at site as required.

4.2.10.5.15 The first circumferential weld joint after a pipe bend shall be after a

minimum straight length of two times the pipe diameter or 500 mm, whichever is less.

4.2.10.5.16 No external support shall be welded on valves and specialities except

as provided by the Manufacturer. 4.2.10.5.17 Welding ends for butt-welding shall be as per Standard V-bevel with

an included angle of 75 degrees. 4.2.10.5.18 The SUPPLIER shall check the bench marks provided by the

OWNER. It shall be the SUPPLIER's responsibility to establish all


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layouts and levels using his own surveying instruments. The SUPPLIER shall protect the bench mark and shall not remove or disturb the bench mark without the approval of the OWNER.

4.2.10.5.19 All pipe flanges and contact surfaces shall be concentric with the axis

of the piping. All flanges and fittings shall be accurately machined and drilled true to the template.

4.2.10.5.20 No welding / gas cutting shall be done locally to valves with soft

seating components in order to prevent distortion of the soft seats. 4.2.10.5.21 All stub and other attachment to be welded on the piping system shall

be carried out in the shop or in pre-fabrication yard and only in situ butt welding alone will be carried out.

4.2.10.5.22 Welding and Non-destructive examination

a. Welding, non-destructive examination of welded joints and repair of weld defect areas shall conform to Clause No.4.2.10.9, "Welding Specification for Fusion Welded Piping Systems".

b. Final welding of joints shall be undertaken only after the set

up of piping is fully checked with respect to layout drawings. c. At equipment terminal points, welding shall be carried out

after taking into account specific requirement and/or recommendations of the equipment supplier.

4.2.10.5.23 Cleaning, flushing & blow-out

a. All piping including valves and specialities shall be cleaned by the SUPPLIER before and during erection to remove grease, dirt, dust, scale and welding slag.

b. Before erection all fabricated pipe work, assemblies, sub-

assemblies, fittings and components etc. shall be thoroughly cleaned internally and externally by blast cleaning or by power driven wire brushes. The brushes shall be of the same or similar material as the metal being cleaned.

c. After erection, all steam, water and condensate lines shall be

mass flushed with water. The cleaning velocities in water and condensate lines shall be 1.2 to 1.5 times the operating velocities in the pipelines. Use may be made of standby pumps wherever available for the purpose.


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d. All compressed air pipework shall be cleaned by blowing compressed air.

e. All fuel oil, tight oil and lubricating oil lines shall be cleaned by

pickling. Alternately, these lines can be cleaned by steam blowing subject to the timely availability of steam for this purpose.

f. All auxiliary steamlines shall be steam blown to effectively

remove scale and slag.

g. For purposes of steam blowing, OWNER will make available low pressure steam as required. It is SUPPLIER's responsibility to install necessary temporary pipework for blowing and remove the same after blowing and render all other assistance to OWNER for carrying out the blowing operation.

h. Electrical tracers of fuel oil lines shall be installed only after

steam blow out and cleaning of the FO lines. However, in the event for any reason steam blow out has to be done after installation of electrical tracing, then due care must be exercised regarding steam temperature to be used for blow out.

4.2.10.5.24 Inspection and testing

a. On completion of erection, the inside of all pipes, valves, fittings etc, shall be clean and free from loose scale and foreign matter before subjecting the line to any test / inspection.

b. All piping systems shall be tested hydrostatically pneumatically

by the SUPPLIER after erection, at pressures given in the applicable codes listed in data sheet or as given in the line designation schedule. The test pressures shall be maintained until all welded / flanged joints are inspected for leakage or atleast for ten minutes.

c. Mechanical equipment and pressure relieving devices should

be blanked-off or removed from the line during pressure testing and control valves should be set in the open position for the duration of the test.

d. Orifice plates should not be erected until hydrostatic testing

and cleaning operations are completed.

e. Lines having check valves should have the source of test


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pressure located on the upstream side.

f. Expansion joints, instruments, filters and similar equipment for which the maximum permissible cold test pressure is lower than the hydrostatic test pressure applied to the system, shall be removed or blanked off from the line before testing. The SUPPLIER shall consult the OWNER / CONSULTANT for specific guidance.

g. Test pressure readings may be taken at the lowest point of the

system being tested provided the effect of static head is taken into consideration.

h. When conditions require a test pressure to be maintained for a

period of time, during which the testing medium in the system might be subject to thermal expansion, provision may be made for the relief of excess pressure thereto.

i. After hydrostatic test any leaky joints shall be cut out and

repaired or completely replaced and test repeated until the test has been satisfactorily passed. If any valve is found to be leaking part the bonnet joint or steam gland packing, SUPPLIER shall replace the gasket or gland packing and retest the system to the satisfaction of OWNER.

j. After completion of hydrostatic test, safety valves, orifice

plates etc., withheld for the hydrostatic tests, shall be installed in an approved manner. Orifice plates shall however be installed after completion of cleaning operations.

k. Clean water at a temperature of not less than dew point or

10°C whichever neither higher, nor exceeding 50°C should be used for hydrostatic test.

l. The rate of pressure increase must not exceed 7 bars per

minute.

m. No one should be allowed near piping/equipment under test when the test pressure is near the yield strength or when test pressure over 35 bars are being applied. The pressure should be lowered by 10% before inspection for the leaks.

n. When draining the fluid, the pipelines should be vented slowly

to avoid excessive vacuum.

o. A block valve is required on the line from the test pump to the pipeline/equipment under test.


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p. Only calibrated test gauges should be mounted in the upright

position. Pump discharge gauge must be visible to the pump operator for the duration of the hydro test.

q. The following test certificates shall be submitted to the

OWNER / CONSULTANT for review: 4.2.10.5.25 Material a. Chemical Composition b. Mechanical properties such as tensile, flattening, bending,

impact etc. as called for in the respective material specification standards.

c. Heat treatment in the case of pipes used for steam service. d. Dimensions. e. Hydrostatic Tests. f. IBR approved Certificates. g. NDT Reports. h. Reports on Visual Examination. 4.2.10.6 Hangers and supports 4.2.10.6.1 All equipment covered under this specification shall comply with all

currently applicable statutes, regulations and safety codes in the locality where the equipment will be installed.

4.2.10.6.2 The SUPPLIER shall design, fabricate and furnish erection

drawings for all hangers, anchors, guides, clamps, stops and supports, auxiliary structures, etc. required for the proper installation and support of the piping.

4.2.10.6.3 It is desirable that supports should as far as practicable, be

arranged adjacent to the pipe joint. 4.2.10.6.4 Constant load hangers / spring hangers shall be provided wherever

necessary for critical piping systems such as main steam piping and boiler feed delivery piping. The variation between hot and cold loads, if variable spring hangers are used, shall not exceed ± 25% of the rated load.


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4.2.10.6.5 Lugs and additional structural members should be suitably welded

to the pipes wherever necessary for hangers and restraints. 4.2.10.6.6 All bare pipes on racks and sleepers shall be clamped at intervals of

atleast 2 M. 4.2.10.6.7 Pipe clamps shall have a minimum thickness of 6 mm. 4.2.10.6.8 All rigid hangers shall provide a means for vertical adjustments

after erection. 4.2.10.6.9 All components of hangers which move relative to the pipe during

expansion shall be connected to the pipe clamps or lugs in such a way that these parts are outside insulation.

4.2.10.6.10 Vertical pipes near tanks should be supported from pad plates

already provided on the tank shell. 4.2.10.6.11 All vertical lines shall be properly supported on the vertical run and

additionally provided with adequate number of lateral restraints where the length of vertical run exceeds 5 M.

4.2.10.6.12 Except for small bore lines, pipes should not be supported from brick walls.

4.2.10.6.13 In selecting position and type of hangers, SUPPLIER shall

endeavor to layout the work such that pipe load stress imposed on the supporting steel are kept to minimum.

4.2.10.7 Valves 4.2.10.7.1 General Technical Requirement

• All valves shall be suitable for the service conditions i.e. flow, temperature and pressure, at which they are required to operate. Valves performing similar duties and of same size, rating, material and type shall be interchangeable with one another.

• All rising stem valves shall be provided with back seat to permit

repacking (of glands) with valves in operation. All valves shall preferably be of outside screw and yoke type.

• All gate valves shall be of full-way type, when in the full open

position, the bore of the valve shall not be constricted by any part of the gate.

• All globe valves of size NB 50 and below shall be of integral type.


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• Reconditioning of seating surface shall be possible without

removing the valve body from the line. • All valves shall be closed by rotating the hand wheel in the

clockwise direction when looking at the face of the hand wheel. • All valves shall have indicators or direction clearly marked on the

hand-wheel so that the valves opening / closing can be readily determined.

• Manually operated valves shall be provided with gear operator of

proven quality conforming to some Internationally accepted Standard and Make if the torque required to operate the valve exceed 13.8Kg.M.

• Integral bypass valve shall be provided for valves of size NB 250

and above with pressure class rating 300, 400 and 600. Integral bypass valve shall be forged gate or globe valve socket welded to ASME B 16.11. The material of integral bypass valve shall be SA 105. The pipe used for mounting the integral bypass valve shall be seamless to SA 106 Gr.B and minimum schedule 80 thickness.

• Integral bypass valve shall be provided for valves of size NB 100

and above with pressure class rating 900 and above. Integral bypass valve shall be forged gate or globe valve socket welded to ASME B 16.11. The material of integral bypass valve shall be A 182 F22. The pipe used for mounting the integral bypass valve shall be seamless to A 335 Gr.P22 and minimum schedule 80 thickness.

• Bypass valves shall be motor operated, if the main valve is motor

operated. • When globe valves are provided as integral bypass valve, the

direction of flow of fluid must be marked on the body of the main valve by stamping or embossing.

• Integral bypass valve shall be supplied in the condition of “As

welded” with the main valve. The size of the valve shall be minimum NB 25.

• All globe valves shall be of vertical stem type. The construction of

globe valves shall facilitate for easy disassembly of the internals (stem and disc).

• The body, seat shall be inclined at such an angle from the vertical


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so as to facilitate closing and to prevent chattering for check valves.

• Direction of flow shall be marked on the body of globe valve and

check valve. • Valves to be installed outside shall be required to have the stem

properly protected against atmospheric corrosion. All valve end connections shall suitably be protected to prevent damage and entry of dirt till erected.

• The valves as well as all accessories shall be designed for easy

disassembly and maintenance. End to end dimensions shall be in accordance to ASME B 16.10 or as per respective codes.

• All valves under the purview of IBR shall be provided with IBR

certificate. • No asbestos or cadmium based material shall be used. • All sampling and root valves furnished shall be of integral body

bonnet type. • Y type globe valves are to be provided in drain and vent root

valves for more than or equal to class rating 900.

4.2.10.7.2 The materials, design and construction of all types of valves shall be subject to the approval of the OWNER.

4.2.10.7.3 All gate valves with pressure seal bonnet and used for steam application

shall be provided with bonnet relief nipples, which will be connected to the piping upstream or downstream of the valve depending on the application.

4.2.10.7.4 The valves used in the vacuum service shall be gland sealed valves. 4.2.11 SPECIFICATION FOR GENERATOR 4.2.11.1 General 4.2.11.1.1 The generator shall be of closed air circuit water cooled (CACW) type

housed in IP 54 enclosure and driven by Steam turbine. The necessary coupling bolts shall also form part of the supply. The generator cooler shall be bottom mounted.

4.2.11.1.2 The nominal output of the unit shall be delivered at power factor from

0.8 PF. Generator shall be suitable for over loading of 110% for one hour in every 12 hours and 150% for 30 seconds. Generator shall be


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able to operate at full load with a variation of ±10% in voltage and ±5% in frequency, with a continued voltage and frequency variation of ±10%. Excitation System shall have a control accuracy of ±0.5%.

4.2.11.1.3 Generation voltage of the Unit shall be 11 kV, 3 Phase R, Y, B in

clockwise rotation. 4.2.11.1.4 The rating and specification of all the required accessories should be

suitable for 11 kV rated voltage. 4.2.11.1.5 The generator shall be suitable for operation over a range of voltage

variation as mentioned at 4.2.11.1.2 and operate satisfactorily under system conditions stated above. The generator shall withstand on the sudden application of maximum load or sudden loss of maximum load and during momentary short circuits or sustained ground faults.

4.2.11.1.6 The generator shall be star connected and the main and neutral leads

shall be brought out of the stator frame for insertion of current transformer for protection, metering and surge protection apparatus. The generator shall be suitable for grounding through grounding resistor. The SUPPLIER shall submit his proposal scheme to explain housing arrangements of various current transformers.

4.2.11.1.7 The short circuit ratio (SCR) shall not be less than 0.5. 4.2.11.1.8 The generator shall be capable of withstanding without damage a

stator current of 150 % for a period of 30 seconds. 4.2.11.1.9 The generator shall be capable of withstanding without damage a

three phase, a line-to-line, a line-to-earth or two line-to-earth short circuit for a period of three seconds, when operating at the rated speed and with an excitation corresponding to a 5 % over voltage at no load.

4.2.11.1.10 The maximum line charging capacity at rated voltage that can be

obtained without negative excitation and with stable operation shall not be less than 35% of rated kVA.

4.2.11.1.11 The saturated rated direct axis sub transient reactance of generator

should not be less than 14% and not more than 18%. 4.2.11.1.12 The moment of inertia of the generator shall be so selected that it

meets the requirement of over speed. 4.2.11.1.13 The machine shall be capable of operating continuously on an

unbalanced system such that, with none of the phase current exceeding the rated current, the ratio of the negative sequence


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component of current (I2) to the rated current (IN) does not exceed 0.1 and under fault conditions shall be capable of operation with the product of (I2/IN)

2 and time (t) in seconds not exceeding 15. In other words, the machine should be designed so as to set the negative sequence relay at 10% of the FLC especially while operating in parallel with grid and system harmonics. (As per IEC in case of direct cooled rotor winding maximum value of I2/In shall be 8% for generator capacity less than 350MVA. Offered value is I2 = 10%).

4.2.11.1.14 In the design of generator, each part shall be so proportioned that the

maximum unit stresses therein resulting from any continuous operating conditions specified shall not exceed one third of the yield point or one fifth of the ultimate strength of the material whichever is less.

4.2.11.1.15 The design of the generator structure and housing in which resonance

might become objectionable shall be so proportioned as to avoid the possibility of resonance with higher rated frequency or multiple and within the frequency variation.

4.2.11.1.16 The synchronous generator shall be designed and constructed so as

to facilitate easy repair / replacement of generator stator bars and rotor pole winding at site without the necessity of going back to works for repairs. Suitable provision shall be made in the base frame of the Generator to facilitate easy removal of the rotor body by sliding it on the bed plate.

4.2.11.1.17 The equipment offered shall be suitable for manual and auto control

from the machine control panels located in the control room. 4.2.11.1.18 The machine shall be suitable for low resistance earthing of the

neutral through neutral grounding resistor to limit the maximum earth fault current to 100 A. The SUPPLIER shall indicate maximum allowable duration for clearing fault inside generator under this condition, to ensure that no damage occurs to the stator laminations.

4.2.11.2 Over Speed 4.2.11.2.1 The generator shall be designed so as to be capable of running at

over speed of the turbine, and all parts of the generator and other equipment shall fully and safely withstand stresses resulting from over speed operation. The rotor shall be tested at 1.2 times the rated speed for two (2) minutes.


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4.2.11.3 Insulation 4.2.11.3.1 The offer shall give a full description of the windings offered both as

to the conductor and insulation. Detailed drawings shall be submitted showing the arrangement of conductors and the thickness and nature of all materials used both for insulation and mechanical protection in the slots of the stator. The insulation, after completion of winding, shall be VPI treated. The SUPPLIER shall furnish detailed write-ups on treatment methods and procedures. The SUPPLIER shall also furnish sufficient details on replacing, servicing / repairing of the generator, etc., in case of damage of the windings for VPI treated windings, giving time factor involved.

4.2.11.3.2 Insulation of minimum `F ' class as specified in IEC specification of

the latest issue shall be used. The quality of the insulation must be such that it is non-hygroscopic and no deterioration will take place when subjected to the maximum, specified operating temperatures nor must it be permanently injured when exposed to this feature as the machine is to operate in a most tropical climate.

4.2.11.3.3 The end turns and coil connections shall have not less than full

insulation, equivalent to, and of the same construction as the coil insulation in the stator slots. The coil and end turns shall be impregnated with high grade insulating varnish. Provision shall be made for tightly wedging the coils in the slots with the wedges which shall not shrink or buckle. Care shall be exercised that the blocking of air passages shall not occur.

4.2.11.3.4 The insulation and taping of the coils shall be such as to prevent

permanent injury from exposure to dampness to provide adequate corona shielding, to withstand high temperatures without injury, to prevent the entering of magnetic particles and to prevent formation of zones.

4.2.11.4 Temperature Rise 4.2.11.4.1 Even though insulation of ‘Class-F’ must be used, when operating

continuously at the maximum continuous rating at its rated 0.8 PF at any working voltages (±10%) and any frequency (±5%) in the range stipulated, the temperature rise shall not exceed Class-B limit at full load. The SUPPLIER shall furnish temperature limit curve, for the specified voltage & frequency range.

The bearing metal temperatures shall be detected by means of duplex

RTDs which shall be hooked upto the temperature scanner of the control panel in the control room.


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4.2.11.4.2 Measurement of temperature shall be made as specified in IEC. The maximum temperature of inlet air shall be taken as 43 Deg. C and the maximum cooling water inlet temperature as 35 Deg. C. Temperature rises shall be within the Class 'B' insulation Temperature rise limits.

4.2.11.4.3 The machine shall further be capable of operating continuously at full

load at 0.8 power factor at 11 kV at frequency 5% below normal, satisfactorily and without undue heating.

4.2.11.4.4 The machine shall be capable of generating more kW than the rated

kW during operation of the machine from 0.8 lagging power factor to unity PF but within the kVA rating of the machine.

4.2.11.5 Efficiency And Output Guarantees 4.2.11.5.1 The guaranteed overall efficiency of the generator at rated terminal

voltage and power factor at 75 Deg. C winding temperature, for the percentage rated output of 100%, 75%, 50% and 25% shall be as furnished. The efficiencies shall be determined by summation of losses method as specified in the latest edition of IEC Publication No. 60034.2 or IS:4889 or equivalent standards. A tolerance will be permitted in the determination of efficiencies as per IEC 60034.2.

4.2.11.5.2 The generator shall be guaranteed to be capable of giving its rated

output under the conditions described earlier without exceeding the temperature rise as specified and without tolerance. If the temperatures are not within the specified limits, the vendor shall do the necessary modifications to bring the temperature within the prescribed limits before acceptance by the OWNER.

4.2.11.5.3 Guaranteed maximum temperature rise, for the stator and rotor

windings of the machine, above inlet temperature of the cooling air not exceeding 45 Deg. C, when operating under rated load conditions shall be as follows:

a) Stator winding by embedded temperature detectors - 85 °C

b) Rotor winding by resistance - 90 °C

4.2.11.6 Cooling 4.2.11.6.1 Generator shall be provided with adequate cooling systems based on

air circulation principle; complete with fans etc., depending on the capacity of the units. The air passages in the stator, rotor fans, coolers, etc., shall be designed to give a smooth and quick flow of air.


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The SUPPLIER should submit drawings in detail to show the cooling system he proposes for the generator.

4.2.11.6.2 The SUPPLIER shall submit a detailed description of the cooling

system taking note of the class of insulation and maximum permissible temperature, size of the unit. Justification for the adequacy shall be given in the description of the cooling system.

4.2.11.6.3 Duplex type RTDs of minimum two numbers each shall be provided in

the cold and hot air passages. 4.2.11.6.4 The coolers shall be constructed out of admiralty brass and shall be

located clear off the stator on the bottom of the generator. Any leak-age from the cooler shall be drained safely and properly and there shall not be any chance of the cooling water finding its way to the stator / rotor windings. Suitable moisture detector device shall be used to detect and warn accidental leakage of water into the cooling air stream. The coolers shall be designed for the shutoff head of the cooling water pumps which will be about 5 Kg/Sq. cm(g) and tested for two times the design pressure. The Cooler shall have isolating valves on either side of the coolers (Upstream insolating v/v shall gate v/v and down stream v/v shall be glove v/v) in cooling water line.

4.2.11.6.5 The cooler shall have ten percent plugging margin and shall be

sectionalised and designed to be suitable for shutting off section by section for cleaning. The design shall be such that the generator can deliver 100% of rated output with one section out of service.

4.2.11.7 Construction 4.2.11.7.1 All parts of generator shall be designed and constructed to safely

withstand maximum stresses during operation, over speed, short circuit conditions, out of phase synchronizing. The pedestal of each generator will be supported on the concrete foundation. All necessary accessories like shims, dowel etc., shall be included in the scope. All sole plates shall be interchangeable and suitably machined and prepared for use at site with minimum amount of work.

4.2.11.7.2 The SUPPLIER shall give full particulars of the extent to which the

generator will be assembled for purpose of shipment and the work to be done at site.

4.2.11.7.3 Pedestal bearings shall be provided for alternator for ease of

maintenance and shall be insulated from ground to prevent shaft currents.


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4.2.11.7.4 After primer, the generator enclosure shall be given two coats of epoxy paint, shade RAL 6024, Munsell Green.

4.2.11.8 Stator The stator frame shall be a single piece to consist of a cylindrical

casing of welded plate construction, reinforced internally in the radial and axial direction by stationary web plates making the entire frame perfectly rigid. Light non magnetic alloy end shields shall be bolted to the ends of the frame. Stator core shall be made up of segmental, annealed punchings of high quality silicon steel to give minimum electrical losses. The stator winding shall be of the double layer lap type with Class 'F' insulation.

4.2.11.9 Rotor 4.2.11.9.1 The rotor construction shall be of cylindrical type. The generator rotor

shall be forged from a single piece ingot of special alloy steel carefully heat treated to obtain excellent mechanical and magnetic properties. A comprehensive series of ultrasonic examinations on the rotor body shall be done to ensure that absolutely no inadmissible internal failures are present and that the material meets the quality standards. Rotors of four pole machines shall be made up of stacked laminations, mounted on the shaft.

4.2.11.9.2 The design and construction of the rotor shall be in accordance with

the best modern practice and shall be fully described in the offer. The factor of safety on yield point of material shall not be less than 1.5.

4.2.11.9.3 The insulation between turns of field winding shall consist of special

epoxy impregnated insulation and glass laminates shall be used for the insulation to ground.

4.2.11.9.4 The rotor spider shall be of steel constructions. To facilitate

synchronization a shorted damper consisting of several round copper bars in each pole head shall be provided.

4.2.11.9.5 The field poles shall be provided with adequate damper windings to

ensure stability under fault conditions and to meet (I22 x t) value of

15. 4.2.11.9.6 The rotor shall have pedestal bearings with oil cooling system so that

the end shields could be removed without disturbing the bearings for inspection of the rotor/stator coils.

4.2.11.9.7 The assembly shall be dynamically balanced at shop at rated speed

and maximum speed.


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4.2.11.10 Earth Terminal Two Nos. of Earth terminals shall be provided. The earth terminals

shall be designed to terminate Galvanized Iron conductors. 4.2.11.11 Speed Regulation

The moment of inertia of the alternator together with that of the turbine shall be sufficient to ensure stability and the speed regulation specified in the section covering turbine for full load rejection. The fly wheel effect shall be incorporated in the alternator and turbines as integral part and not added in the shape of separate weights, rings or other means.

4.2.11.12 Shaft 4.2.11.12.1 The generator shaft shall be made of best quality forged alloy steel,

properly treated. The shaft shall be of ample size to operate at all speed, including maximum over speed without vibration or distortion and shall be able to withstand short circuit, heavy momentary overloading and other stresses without damage. To prevent the flow of harmful shaft currents damaging the bearings, suitable shaft earthing shall be provided.

4.2.11.12.2 A complete set of test reports covering metallurgical strength,

crystallographic and ultrasonic tests performed in each shaft during various stages of its manufacturing shall be furnished as also the complete specifications of the shaft material forging and its design parameters such as stresses and critical speed.

4.2.11.12.3 The generator shaft shall have a suitably shaped flange for coupling

to the turbine. The coupling flange shall be forged integral with the shaft and the shaft coupling shall comply with the requirements of IEC for shaft coupling. All coupling bolts, nut and nut guards for coupling shall be included in the scope. The alignment limit for the shaft shall be as per the latest NEMA / DIN standards.

4.2.11.13 Space heaters & RTDs 4.2.11.13.1 Suitably rated heaters shall be installed within the enclosure of the

generator. Location and the maximum temperature of the heaters shall be such that no damage can be caused to any insulation. Heaters shall be suitable for operation on a single phase 230 V AC supply. A suitable double pole switch shall be mounted on or adjacent to the stator frame for the manual switching of the heaters.


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4.2.11.13.2 Duplex type RTDs shall be provided in the following locations, which shall be hooked up to the temperature scanners:

a) Coil sides - 4 Nos. per phase.

b) Stator core - 4 Nos. c) Bearings - 2 nos. each for DE and NDE d) Cold & Hot air circuits - 2 Nos. per stream. e) Exciter Field - 2 Nos.

4.2.11.14 Excitation System 4.2.11.14.1 A brushless exciter shall be used and it shall be mounted on the out

board end of the generator frame. A digital excitation regulation system (with twin redundant auto and a manual back-up channel) shall be provided to control the excitation of the synchronous generator by varying the current applied to the field of the main exciter. The digital auto excitation regulator shall be fed from Permanent Magnet Generator (PMG) which shall be coupled at the end of the generator shaft. Alternative arrangement shall be made available for supply to the excitation regulator, to enable operation of the set even during failure of PMG supply.

4.2.11.14.2 The excitation regulation system shall be of the ‘state-of-the-art’

microprocessor technology, high speed, fully tropicalised, automatic excitation regulator. It should be complete with necessary cable entries, adjusting rheostats, auto / manual control facilities, on / off and raise / lower selector switches. The following minimum displays shall be made available in the operator pad / digital display unit:

a) Exciter Field Current b) Exciter Field Voltage c) Generator Voltage d) Generator Power Factor 4.2.11.14.3 The excitation system shall be provided with the following minimum

features: a) Generator voltage control b) Auto power factor control c) Field current control d) Excitation buildup during startup and field suppression

shutdown e) Limiter for the under excited range & delayed limiter for

overexcited range f) PT fuse failure detection and auto changeover g) Diode failure supervision

h) Stator current limitation for lagging & leading loads


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i) Rotor current limiter j) Load angle limiter

k) Volts / Hz limiter 4.2.11.14.4 The system offered shall have the following facilities:

a) Two independent auto cum manual channels. Each channel will have it’s own thyristor / power bridge arrangement.

b) Back-up manual mode for testing / emergency operations c) Follow-on mode for each operation to have bumpless transfer

between auto channel and manual channel d) Audible annunciation for internal faults and for channel

changeover with accept provisions e) RS485 Communication port with MODBUS protocol for

configuration / setting option from PC / DCS f) Digital display & keypad, for front panel operation

g) All necessary software for interfacing the system with PC / DCS

h) Self diagnostic facility 4.2.11.14.5 AVR panel shall have a height of 2200 mm, including base channel of

100 mm. 4.2.11.15 Accessory Equipment 4.2.11.15.1 Main power terminal boxes shall be fully phase segregated and

suitable for the envisaged type of connection arrangement. 4.2.11.15.2 The generator shall be provided with stator temperature sensors

installed in the stator winding with leads and shall be brought out to the terminal boxes. RTDs shall be provided for hooking up to the temperature scanner in the control panel. Space heaters for anti-condensation shall also be provided. Necessary vibration transducer, displacement transducers with transmitters shall be provided which shall be hooked up to the control panel in the control room.

4.2.11.15.3 The SUPPLIER may propose to accommodate auxiliary equipment like

current transformers, potential transformers, lightning arrestors and surge capacitors in the generator terminal boxes, if available as their standard practice. Requirements of such equipment shall be in accordance with IS / IEC standards and the specifications furnished elsewhere in this document.

4.2.11.15.4 Terminal cubicles, if used for single core cable connections, shall be

provided with non-magnetic type gland plates.


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4.2.11.16 Protective Devices 4.2.11.16.1 The protective devices as listed under the topic Protection, Metering

and Control cubicles and the schematic diagram shall be offered. 4.2.11.16.2 The SUPPLIER shall note the system conditions like voltage,

frequency variations, SC level at the location of the proposed generating units and offer suitable generating equipment with necessary accessories required for satisfactory working of the generating units.

4.2.11.17 Tests 4.2.11.17.1 The generator shall be completely assembled at works and type tests

as specified below shall be conducted on the assembled unit and auxiliaries as per the latest edition of IS / IEC. Detailed test reports shall be furnished.

4.2.11.17.2 Tests The following tests shall be carried out on the machine:

a) Measurement of DC resistance of stator and rotor windings. b) Insulation resistance of stator winding (before and after high

voltage tests), rotor winding, bearings and embedded temperature detectors.

c) High voltage test of stator and rotor windings at industrial

frequency. d) Phase sequence. e) Determination of open-circuit characteristics. f) Determination of short-circuit characteristics. g) Over speed at 120% for 2 minutes and vibration there of. h) Pressure test on coolers for close - circuit cooling. i) Determination of efficiency by separation of losses methods. j) Vibration. k) Impedance test of the rotor winding.


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l) Stator winding capacitance and tan delta measurement. m) Measurement of Shaft Voltage n) Polarization Index o) Wave form recording. p) Shaft vibration measurement q) Momentary over current test for 150% of rated current for 30

Secs. r) Harmonics s) Voltage balance test t) Air gap u) Noise test v) Temperature rise test at iron loss, copper loss with equivalent

method including exciter. In addition to the routine test, the following type tests shall also be

carried out, if the generator manufacturer had not carried out the type tests on similar machine (kW rating & speed):

a) Mechanical run test for temperature rise.

b) Temperature rise test of windings. c) Instantaneous Three (3) phase short circuit test at rated speed

and 30% voltage. d) Determination of reactances and time constants.

4.2.11.17.3 Tests on Exciters

a) High voltage test

b) Measurement of resistances

c) Measurement of insulation resistance


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4.2.11.17.4 Tests at Site

Site tests for generator shall include the following: Mechanical run and vibration measurement. Measurement of stator and rotor winding insulation resistance. Over speed test Measurement of shaft voltage

Measurement of stator and rotor winding resistance

Phase sequence test before excitation (with residual voltage) and

after excitation

Open circuit and short circuit test

Load acceptance and rejection test at selected loads from no load to full load.

Overall response of machine and excitation system

Adjustment of excitation regulator parameters

Synchronising test

Dynamic checking of all protective functions

Checking and commissioning of various other auxiliary equipment. Function of RTD and it’s circuits

Pressure tests on coolers

Tests on other equipment like CTs, PTs, LAs, shall comply with the routine tests etc., as per relevant standards.

Test reports for all the type tests on the generator, CTs, PTs, & LAs carried out on similar equipment already supplied shall be furnished for approval.


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4.2.12 SPECIFICATION FOR PROTECTION, METERING, CONTROL CUBICLES.

4.2.12.1 Scope

This specification covers the requirements of protection, metering, synchronising and control cubicles and the associated equipment mounted therein.

4.2.12.2 Codes and Standards 4.2.12.2.1 The design, manufacture and performance of equipment covered by

this specification shall conform to the relevant Indian Standards and Codes. Where Indian Standards are not available, they shall conform to relevant British, IEC and American Standards.

4.2.12.2.2 The equipment shall conform to following standards in particular.

IS:1248 - Direct acting electrical indicating instruments. IS:2705 - Auxiliary current transformers. IS:3156 - Auxiliary potential transformers. IS:3202 - Code of practice for climate proofing of

electrical equipment. IS:3231 - Electrical relays for power system protection. IS:5578 & IS:11353

- Marking and arrangement of switchgear, bus-bars, main connection and aux. wiring.

IEC:44 - Instrument Transformers IEC:185 - Current Transformers IEC:186 - Potential Transformers IEC:255 - Electrical Relays IEC:1036 - Static Meters

4.2.12.3 Scope of Work The scope of design, manufacture, testing and supply of equipment

covered under this specification shall include but not necessarily be limited to the following:

4.2.12.3.1 Design, engineering and fabrication of cubicles as per the

specifications.


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4.2.12.3.2 Supply and mounting of all the equipment and auxiliary equipment like auxiliary relays, test switches, test blocks, plugs, etc., necessary for satisfactory functioning of the control and protection system.

4.2.12.3.3 The protection system shall be provided with communication ports /

auxiliary contacts to integrate the system with the PURCHASER’s DCS /ECS for the purpose of Data Acquisition.

4.2.12.3.4 All internal wiring between all equipment upto the terminal blocks and

the interpanel wiring. 4.2.12.3.5 Preparation and furnishing of all data / drawings / documents as per

the requirement and specifications. 4.2.12.3.6 Testing at works of the cubicles and the mounted equipment. 4.2.12.4 Design Requirement 4.2.12.4.1 Constructional Features 4.2.12.4.1.1 The cubicles shall be of 'Simplex' type, with height of 2200 mm,

including 100 mm base channel. 4.2.12.4.1.2 Cubicles shall be sheet steel enclosed dust and vermin proof type.

Cubicles shall be floor mounting, free standing, formed on a framework of standard sections. The enclosure shall be of cold rolled sheet of minimum 3 mm for front and back and 2.5 mm thick for rest. The supporting structure shall be so designed to form a rigid structure.

4.2.12.4.1.3 All doors and openings shall be provided with neoprene gaskets. 4.2.12.4.1.4 The cubicles shall be suitable to be installed on a base frame supplied

in one piece along with foundation bolts. Amply dimensioned oblong holes shall be provided at the bottom of all the cubicles for their installation on base frame, in addition the cubicles shall have an additional base channel at the bottom with smooth surface. Anti vibration type mounting shall be provided.

4.2.12.4.1.5 A suitable removable undrilled gland plate shall be provided for cable

entry from bottom. 4.2.12.4.1.6 The degree of protection of the cubicles shall be IP 42.


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4.2.12.4.2 Mounting 4.2.12.4.2.1 All instrument and control gears and relays shall be mounted on the

front. All equipment shall be flush or semi-flush type. 4.2.12.4.2.2 Checking and removal of components shall be possible without

disturbing the adjacent equipment. It shall be possible to set all the measuring relays “insitu”. All mounted equipment inside the cubicles shall have “identification tags” of self sticking engraved tapes; in addition identification numbers shall be painted on cubicle wall to give permanent identification mark. The mounting of terminal blocks and any other auxiliary equipment such as transducers, interposing CTs etc. shall be done in such a way so as to be readily accessible but without impeding the access to internal wiring and components.

4.2.12.4.2.3 The centre line of switches, push buttons and indicating lamps shall

be not less than 750 mm from the bottom of the cubicle. The centre line of relays and meters shall not be less than 450 mm from bottom of the cubicle. All switches, push buttons, indicating lamps, relays, etc. shall be neatly arranged in a matching manner.

4.2.12.4.2.4 The cubicle shall be matched with other cubicles in dimension, colour

and mimic. 4.2.12.4.3 Type

All the cubicles shall be of simplex type and shall consist of vertical front panels with mounted equipment and rear wiring access. Doors shall have handles with locking facility.

4.2.12.4.4 Wiring 4.2.12.4.4.1 All wiring shall be done with PVC insulated, 1.1 kV grade, single-core

multi strands (minimum 3 strands) annealed copper conductors suitable for temperature and humidity specified. The cross section of the wires for voltage, current and control circuits shall be 2.5 Sq. mm and that for the alarm circuits shall be 1.5 sq. mm. The wires shall be vermin proof and shall be laid in plastic gutters.

4.2.12.4.4.2 Each wire shall be identified at both ends with wire numbers by

means of PVC ferrules. Colour coding for the wires shall be as per IS:375. Each cable shall be identified with aluminium tags.

4.2.12.4.4.3 The terminal boards shall be set at 45 Deg. to the side panels for easy

access. Minimum 20% spare terminals shall be provided on the cubicles.


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4.2.12.4.4.4 The terminals shall be suitable to receive crimped wires to give positive connection. All terminals shall be properly shrouded against accidental contact. Sufficient terminals shall be provided so that not more than one wire is connected to each terminal.

4.2.12.4.4.5 The terminal blocks shall 1.1KV, 10 amps rated, one piece moulded

complete with insulated barriers, stud type terminals, washers, nuts and lock nuts and identification strips.

4.2.12.4.4.6 Terminal blocks for the CT and PT secondary leads shall be provided

with test links and isolation facilities. Also CT secondary leads shall be provided with short circuiting and earthing links.

4.2.12.4.5 Painting 4.2.12.4.5.1 All metal surface shall be thoroughly cleaned and degreased to

remove mill scale, rust, grease and dirt. Fabricated structure shall be pickled and then rinsed to remove any trace of acid. The under surface shall be prepared by applying a coat of phosphate paint and a coat of yellow zinc chromate primer. The under surface shall be made free from all imperfections before undertaking finishing coat.

4.2.12.4.5.2 After preparation of the under surface, the relay and control panel

shall be spray painted with two coats of final paint. Colour shade of final paint shall be pebble grey, shade RAL 7032 with glossy finish and shall be duly approved by the PURCHASER before final painting is done. The finished panel shall be dried in stoving oven in dust free atmosphere. Panel finish shall be free from imperfections like pin holes, orange peels, run off paint etc. The vendor shall furnish painting procedure details for approval by the PURCHASER / CONSULTANT.

4.2.12.4.5.3 All unpainted steel parts shall be cadmium plated or suitably treated

to prevent rust corrosion. If these parts are moving element then these shall be greased.

4.2.12.4.6 Cubicle Illumination 4.2.12.4.6.1 Compact fluorescent lamps working on 240 V AC, operated by door

switches shall be provided for internal cubicle illumination, in each panel.

4.2.12.4.6.2 A 240V, 1-Phase, 5 Amp., 3 Pin Socket shall be provided in the panel

corridor or interior of each cubicle with on-off switch for connection of hand lamps. This socket shall be metal clad type with a spring loaded flap.


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4.2.12.4.7 Earthing 4.2.12.4.7.1 A continuous 25 mm x 3 mm copper (tinned) or equivalent aluminium

/ GI earth bus shall be provided running along the full lengths of the cubicles. Suitable arrangement shall be provided at the two ends for connection to the plant earthing system.

4.2.12.4.7.2 Each cubicle and the equipment mounted on each cubicle shall be

securely connected to the earth bus. For this purpose, the earth wire shall be looped from equipment to equipment and both ends of the earth wire shall be connected to the earth bus.

4.2.12.4.8 Space Heaters Panel space heaters shall operate off 240 V AC and shall be supplied

complete with on-off switch, fuse and thermostat. A common thermostat shall be provided for the entire panel. The thermostat shall maintain the internal temperature above the ambient temperature to prevent moisture condensation.

4.2.12.4.9 Mimic 4.2.12.4.9.1 Mimic diagram shall be provided on cubicles. Mimic diagram shall be

screwed on to the cubicles and shall be made of anodised aluminium or plastic of approved fast colour. The mimic shall be 10 mm wide for horizontal run and 5 mm wide for vertical run.

4.2.12.4.9.2 Semaphore indicators used for isolator positions, they shall be so

mounted in the mimic that isolator (or breaker) closed position shall complete the continuity of the mimic. The mimic diagram shall incorporate red and green lamps for isolator position indication and controlling switches with indicating lamps for breakers.

4.2.12.4.9.3 Alternatively, automatic semaphore indicators for isolators and built in

hand operated semaphore and position indicating lamps for breaker control switches may be provided.

a) The lamps will remain steady where the hand operated

semaphore position correspond with the breaker position.

b) The lamps shall flicker with a time delayed alarm if the semaphore position does not correspond with the breaker position.

4.2.12.4.9.4 The colours for various voltages in the mimic diagram shall be as

below.


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Voltage Level Mimic Colour Shade as per IS:5

EHV Signal Red 537

11 kV Canary Yellow 309 4.2.12.4.10 Ten (10) nos. of illuminated push buttons with covers along

with master trip relay (86) with a minimum of 2NO + 2NC (Model VAJH13 or equivalent) shall be wired up to TBs for load shedding purpose.

4.2.12.4.11 Equipment Specifications 4.2.12.4.11.1 Transducers Transducers with output of (4-20) mA shall be arranged by the

BIDDER, wherever required. Transducers for voltage, current, frequency, Megawatt, MVA, MVAR and power factor as indicated in the tender single line diagram shall also be provided.

4.2.12.4.11.2 Indicating Lamps These shall be switchboard type of low power consumption, LED

cluster type lamps and shall be supplied complete with necessary resistors. Lamps shall be provided with screwed translucent covers to diffuse light. The lamp covers shall preferably be unbreakable, moulded, heat resistant material and shall be provided with chromium plated bezels.

4.2.12.4.11.3 Control Switches 4.2.12.4.11.3.1 All control switches shall be rotary, back connected type

having cam operation contact mechanism. Phosphor bronze contacts shall be used on switches.

4.2.12.4.11.3.2 The handle of control switches used for circuit breaker

operation shall turn clockwise for closing and anti-clockwise for tripping and shall be spring return to neutral from close / trip with lost motion device. Each switch shall be provided with external red and green indicating lamps.

4.2.12.4.11.3.3 The no. of poles in any selector switch shall be

restricted to eight (8) numbers, by providing multiplication contactors / relays to meet scheme requirement.

4.2.12.4.11.4 Control MCBs


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Control MCBs shall generally be mounted on the top half of the cubicles. All MCBs shall be provided with suitable identification labels.

4.2.12.4.11.5 Annunciation Following audible alarm / annunciations, with distinct tones shall be

provided for

a) Protective relay operated - Alarm b) Protective relay operated - Trip c) DC failure with AC as auxiliary supply

The scheme shall include necessary acknowledge & reset push

buttons. The annunciator shall have first-in facility. 4.2.12.4.11.6 Relays 4.2.12.4.11.6.1 All relays shall be switchboard pattern, back connected draw out

type suitable for flush mounting and fitted with dust tight covers.

4.2.12.4.11.6.2 A set of test block and test lead for necessary secondary

injection tests shall be included. All relays in draw out cases shall have suitable spring loaded contacts for inserting test block.

4.2.12.4.11.6.3 The rating of the auxiliary contacts shall not be less than

5 amp at 240 V AC and 15 amp for 110 V DC. 4.2.12.4.11.6.4 Relay terminals to be of stud type / self-locking plug-in type. 4.2.12.4.11.6.5 The detailed list of protective relays for each cubicle is listed

elsewhere. The relays shall be supplied with the necessary accessories to make the system complete.

4.2.12.4.11.7 Clock, Name and Identity Plates 4.2.12.4.11.7.1 One No. digital clock with minimum 50 mm height digital

display shall be fitted in an attractive position on the complete cubicle assembly. The clock shall have a hand operated device for adjustment of clock hands from front.


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4.2.12.4.11.7.2 All instruments, relays and other electrical devices mounted on the cubicle shall be provided with plates bearing the manufacturer's name, serial number and the electrical rating data.

4.2.12.4.11.7.3 Reverse engraved name plate at least 10 mm wide bearing

suitable identification marks shall be fixed in the interior of the switchboard, at the test blocks, at the MCB blocks and at the cable terminals. Similar plates shall be fixed to the exterior of the switchboard in appropriate places to indicate the functions of control switches, push buttons, lamp and other equipment not incorporated in the mimic diagram.

4.2.12.4.11.7.4 Name plates bearing respective circuit designation of 50 mm

width etched in 40 mm high letters shall be mounted on the top of the front side and back side of each cubicles shall be supplied and fixed in such a way that these can be removed and refitted when desired.

4.2.12.4.11.7.5 Each equipment shall have a rust proof metal tag permanently

attached to it with the tag number. 4.2.12.4.11.8 Auxiliary PT and CTs 4.2.12.4.11.8.1 Necessary auxiliary potential transformers for open delta

potential polarisation and auxiliary current transformers, wherever required, shall be included in supply.

4.2.12.4.11.8.2 Auxiliary CTs required for summation of two or more feeders

and auxiliary PTs required for galvanic isolation of different synchronising inputs shall be included.

4.2.12.4.11.8.3 The instrument transformers shall have the following accuracy

class

Potential Transformer Current Transformer

Measurement 0.2 0.2S Protection 3P 5P20 & PS

4.2.12.4.11.8 Synchronization

Panel mounted synchronising equipment complete with double voltage & frequency meters, synchroscope, synchronising check and guard relays, ‘no voltage’ relays, synchronising cut off switch, lamps, breaker selection switches for all the breakers to be synchronised, auto synchroniser with output for governor &


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AVR controls etc. shall be provided. The TG shall be considered for 15 nos. breaker synchronisation including back synchronisation with the grid, PLC based synchronization scheme is to be offered.

4.2.12.4.11.9 Trivector / power measurement metering

4.2.12.4.11.9.1 Two (2) numbers of integrating meters of the Trivector or

equivalent types capable of indicating all phase instantaneous parameters and recording kWH, kVARH and kVAH directly shall be provided. They shall be capable of record / display of harmonic data upto 51st harmonics.

4.2.12.4.11.9.2 These should be suitable for 3 phase, 4 wire 50 Hz circuits with

unbalanced loading and with two sets of elements connected to current and potential transformers of specified ratio.

4.2.12.4.11.9.3 The meters shall be of digital type, class 0.2 or better with

communication port, RS485 interface - MODBUS RTU protocol, for hooking up to PC and plant DCS. Necessary softwares for downloading of stored parameters and analysis shall also be supplied. Each of these meter shall be provided with a minimum of three analog out puts in addition to soft signal at modbus.

4.2.12.4.11.9.4 Meters for frequency, power factor and MW should be of digital

type. 4.2.12.4.11.10 Temperature scanners Microprocessor based temperature scanner shall be provided to

process the signals from RTDs of the generator windings / bearings / cooling air paths. The scanner shall have scrolling display with output relays for High-Alarm and High-Trip signals, individually for all channels. It shall be possible to set the parameters through membrane type keypad. Resolution for the complete range shall be not less than 0.1° C with accuracy of better than ±1%. The scanner shall be provided with RS 485 communication port, suitable for MODBUS RTU protocol.

4.2.12.4.12 Details of Protective Relays 4.2.12.4.12.1 Protection of the generator shall be achieved through

microprocessor based, composite protective digital relays, with one as primary and the other as back-up. Both the relays shall include the following minimum protective functions:


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4.2.12.4.12.1.1 Generator - Accidental energisation protection

- Over & Under voltage (1st and 2nd stage) - Under & Over frequency(1st , 2nd & 3rd stage) - Field failure - Reverse Power - Low forward power - Voltage restrained over current - Generator differential - Stator standby earth fault protection (95% and 100%) - Local breaker back-up / struck-up - Negative sequence

- Voltage balance / PT fuse failure - Over fluxing Protection - Pole slipping protection - IDMT overcurrent (1st and 2nd stage) - Instantaneous overcurrent - PT fuse supervision - Restricted earth fault protection - Thermal Overload - Rotor earth Fault

4.2.12.4.12.1.2 Generator transformer protection - Differential protection - Restricted earth fault protection - Directional overcurrent and earth fault - Over fluxing - Oil and winding temperature - Oil Level - Buchloz relay - Alarm and trip for all above 4.2.12.4.12.1.3 Overall - Overall differential protection 4.2.12.4.12.2 The SUPPLIER shall make available a set of output contact,

duly configured for one stage of the following voltage / frequency function:

- Over voltage - Over frequency - Under voltage - Under frequency


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4.2.12.4.12.3 Both the generator and generator transformer protection relays shall have the following minimum features:

- Communication port, RJ45 interface – IEC61850

protocol, for hooking-up to plant DCS, for down loading & parameter settings

- Necessary software, for processing of data. - Event recording facility, for a minimum of 32 events. - Disturbance recording & analysis facility - All the event, disturbance and the fault records shall be

stored in the internal memory of the generator protection relays and shall be capable of being downloaded when required.

- Self diagnostic facility 4.2.12.4.12.4 Additional discrete relays shall be provided for the following

main functions, even if the same is available in the composite relays:

- Rotor Earth Fault protection - 95% Stator earth fault relay to cover 95% of winding

protection with necessary current and voltage operated relays.

- 100% stator earth fault protection with third harmonic over voltage principle may be provided based on the system and generator suitability along with minimum setting available in the relay for the above function

- Static / microprocessor based reverse power relay, with settable range of 0.5% connected from Class 0.2 core CT

4.2.12.4.12.5 Additional discrete relays shall also be provided for the

following auxiliary functions: - Master trip relays - Trip circuit supervision relays for each trip coil of the

tandem circuit breaker and all master trip relays - DC supply failure relay - Auxiliary relays, if required - Rotor earth fault relay - Check synchronization relay - Guard relay - No volt relay - Dead bus relay


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4.2.12.4.12.6 Discrete relay for overall differential protection shall be envisaged. This relay shall be of numerical type suitable for three winding transformer (three sets of CT inputs).

4.2.12.4.12.7 Discrete relay for grid islanding purpose shall be envisaged.

This shall consist of the following relays: - Vector surge relay - Master trip relay - Trip circuit supervision relays Generator and generator transformer shall provided with

following signal through kWT for plant DCS: - Current - Power factor - MW - MVAR - MVA - Frequency - Voltage In addition, following for governor: - MW - MVAR 4.2.12.4.12.8 A common PC, loaded with necessary software and interface

units to receive signals from RS 485 and RS 232 communication ports shall be supplied, along with A4 LaserJet Colour printer. PC shall be with minimum configuration of Intel I7 processor with CPU speed 2.933 GHz, FSB 2933 MHz, Cache 18 MB, 8GB RAM DDR3 / 500 GB SATA @ / 15000 RPM / No-FDD/DVD-RW/ 32 X combo / 21” TFT monitor with 4 USB and 1 serial ports, LAN network interface, Keyboard, Mouse, 1 parallel port. The PC and Printer shall be supplied with latest configuration as available in the market. The PC shall also be loaded with complete Software required for interfacing, downloading, uploading, programming with relays and meters.

4.2.12.4.12.9 Connection configuration of the protective relays shall be as

shown in the enclosed ‘Electrical Schematic Diagram’.


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4.2.13 SPECIFICATION FOR SEGREGATED PHASE BUSDUCT, NGTR / LAVT CUBICLES AND SEALED TVM CUBICLE

4.2.13.1 Segregated Phase Bus ducts 4.2.13.1.1 Standards The equipment covered under this specification shall unless

otherwise stated be designed, constructed and tested in accordance with latest revisions of relevant Indian Standards.

4.2.13.1.2 Design Particulars

Continuous Current Rating : 2000Amp Rated Voltage Class : 12 kV System Voltage : 11 kV, Resistance Earthed BIL (kV Peak) : 75 One minute power frequency dry withstand voltage (kV rms)

: 28

Short time rating for 3 sec (kA rms) : 40 Dynamic Rating (kA Peak) : 100 Maximum hot spot temperature of busbar at rated current

: 85 Deg. C

Maximum hot spot temperature of enclosure at rated current

: 70 Deg. C

Busbar Material : Copper Enclosure : Aluminium Alloy Insulators : Type : Porcelain Voltage (Rated / One min. power frequency) (kV rms)

: 11 / 22

IS:2099 - HV Porcelain Bushing IS:2544 - Porcelain Post Insulator IS:2629 - Hot Dip Galvanising IS:5082 - Bus conductor material IS:6005 - Phosphate treatment of Iron and Steel


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Impulse withstand voltage (kV Peak)

: 75 kV

Earthing : Generator neutral earthed

through resistance

4.2.13.1.3 Definition A segregated phase busduct is one in which phase conductor

with its associated connections, joints, accessories and insulating supports are enclosed in an earthed metal housing with either metal or insulation barrier between the phases. If the BIDDER offers insulated barriers, the type, composition, electrical withstand characteristics and thickness of the insulating material used shall be indicated by the BIDDER in his bid and shall be subject to the PURCHASER's approval.

The 11 kV busduct shall connect the generator to generator

transformer to 11 kV generator tandem circuit breaker panel, generator & NGTR Cubicle with tap off to LAVT Cubicle with necessary bends, joints, wall through busducts, phase cross over chambers, disconnecting links and tap-off busducts. The fault level along with the distance of busduct to be considered shall be as follows:

Busduct STC Generator to generator transformer 40 kA for 3 Sec Generator Transformer to CB panel 40 KA for 3 Sec Tap Off for LAVT Panel 40 kA for 3 Sec Generator to Star Point formation 40 kA for 3 Sec Star Point to NGTR Panel 40 kA for 3 Sec

4.2.13.1.4 Dedicated CTs and PTs of rating furnished in the tender single

line diagram shall be provided in the busduct for open access metering. Suitable provision for sealing of this chamber and the junction boxes shall be made available. CT for future use as ‘spare’ shall also be envisaged as indicated in the tender single line diagram.

4.2.13.1.5 General Requirements


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4.2.13.1.5.1 Bus Enclosure This enclosure shall be made of aluminium alloy of minimum 3

mm thickness. 4.2.13.1.5.2 Mechanical Strength The design of the busduct enclosure shall be such that it will

withstand the internal or external pressures resulting from the following: a) Normal operating conditions b) Momentary short circuit current (peak) c) Rigours of adverse weather conditions, and d) Combination of the above.

The housings shall be of sturdy construction to have inherent

strength to withstand the above forces. 4.2.13.1.5.3 Construction The entire bus duct shall be designed for indoor installation with

a dust and vermin proof construction. Busduct shall have degree of protection better than equal to IP 54 for indoor and IP55 for outdoor.

4.2.13.1.5.4 Painting The inside of the bus enclosure shall be treated with a matt paint

of dark colour, preferably black to facilitate efficient heat dissipation. The bare enclosure with above painting shall be designed so as not to exceed the temperature specified elsewhere when the conductor is carrying rated current. The BIDDER shall submit supporting test certificates.

The outside of the enclosure shall be given a finish of epoxy paint

with shade flint / pebble grey RAL 7032. 4.2.13.1.5.5 Temperature Rise Under normal operating conditions, the hot spot temperature of

the conductor shall not exceed 80 Deg.C i.e. temperature rise of conductor shall not exceed 35 Deg.C over an ambient temperature specified in the design basis. The bus duct shall be of natural cooling type.


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4.2.13.1.5.6 Bellow Joints Joints consisting of rubber bellows shall be provided on the bus

enclosure at following points: a) At terminations at Generator b) At terminations at switchgear cubicles 4.2.13.1.5.7 Flexible Expansion Joints Flexible expansion joints for the enclosure shall be provided

wherever deemed necessary by the manufacturer. The flexible joints shall take care of expansion and contraction due to temperature variations and fault conditions.

4.2.13.1.5.8 Bonding

Necessary bonding shall be provided at the above expansion joints if made of insulating material.

4.2.13.1.5.9 Terminal Enclosures and Flanges

Three-phase terminal enclosures shall be provided with flanged ends with drilling dimensions to suit the flanges at equipment terminals.

The flanges shall be provided with gaskets, nuts, bolts, etc. It shall be the responsibility of the manufacturer of the

busduct to coordinate with various equipment (by others) to which his busduct has to be terminated to ensure proper alignment of the busduct with this equipment.

4.2.13.5.10 Inspection Covers Provision shall be made for periodic inspection of insulators by

means of inspection covers. The inspection covers shall be provided with quick acting stainless steel clamps and shall have gaskets.

4.2.13.5.11 Drain Plugs and Vents Filter type drain plugs shall be installed at low points along the

run of the busduct to drain out automatically any moisture condensing within the bus enclosure. The drain plugs shall be fitted with porous filter elements which will permit the escape of moisture but prevent the ingress of dust. The filter


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elements shall be easily removable for cleaning purposes. 4.2.13.5.12 Gaskets

The gasket material and thickness shall be so selected as to satisfy the operating conditions imposed by temperature, weathering durability etc. Care shall be exercised to ensure that covers fit easily, that the required compression of the gaskets can be obtained without damage to the inspection covers by bolts and that covers do not bend after this compression has been applied. Over-compression of the gaskets shall be avoided.

The material of the gaskets shall preferably be neoprene

closed cell sponge rubber or equivalent.

Flange gaskets shall be provided at the equipment terminal connections.

4.2.13.5.13 Miscellaneous Hardware

The busduct shall not have any through bolts. All nuts and bolts shall be mild steel hot dip galvanised. MS spring washers shall be provided for making satisfactory joints. Clamps, splice plates, etc. shall be provided wherever necessary.

4.2.13.5.14 Earthing

Necessary earthing arrangement as applicable shall be pro-vided with clamps to receive the station earthing bus. All accessories and hardware required for the earthing arrangement shall be provided.

4.2.13.6 Bus Conductor 4.2.13.6.1 Material The material of the conductor shall be of high grade Copper. 4.2.13.6.2 Rating

The bus conductor shall be designed to carry the rated current under normal site operating conditions without exceeding a hot spot temperature of 85 Deg. C. Also the temperature of the bus shall not be exceed 250 Deg. C while carrying the specified short circuit current for three seconds when a fault occurs at the operating temperature.


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4.2.13.6.3 Shape

The section of the bus conductors used shall be rectangular, tubular, hollow square, hollow rectangular, double channel or hollow hexagonal/octagonal type.

4.2.13.6.4 Mechanical Strength

The bus conductors and insulated supports shall withstand without permanent deformation, deterioration of conductor material and reduction in the BIL value of the busduct, the stresses consistent with the momentary short circuit current.

4.2.13.6.5 Painting The bus conductor may be given a coat of matt black paint to

facilitate heat dissipation. The bare conductor with above painting shall be designed to carry the normal rated current without exceeding temperature rise as specified. The manufacturer shall submit supporting test certificate.

4.2.13.6.6 Losses The losses in the conductor shall be limited to such a value that

the temperature rise of the conductor does not exceed the specified values. The losses should be such that an optimal operating cost is obtained.

4.2.13.6.7 Joints Adjacent sections of the bus conductors shall be bolted or

welded to provide an efficient, electrically continuous and mechanically strong connection.

Welded Rigid Joints Joints shall be highest quality done as per the recognised

methods of welding practice. Suitable aluminium or copper connectors shall be provided wherever the bus sections change.

Welded Expansion Joints Flexible aluminium or copper connectors welded to the main

busbars shall be provided wherever deemed necessary.


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Bolted Rigid Joints The connectors shall be of the same material as the conductor

and these shall be silver plated to ensure an efficient connection. The bolting schedule and contact pressures shall conform to accepted codes of practice.

Bolted Flexible Joints Flexible braided copper connections shall be provided at the

equipment terminal connections. Bimetallic connectors shall be provided between the busbar and the copper flexible if the bus conductor is of aluminium alloy. The joints shall be capable of 25mm settlement of equipment mounting pads. The joints shall be suitably designed to take care of the vibration at the terminals as well as the expansion and contraction of the busbars.

Bolted Expansion Joints Expansion joints made of aluminium or copper strips shall be

provided wherever deemed necessary by the vendor, to take care of expansion and contraction of the busbars under normal operating conditions.

All the above joints shall be tested for temperature rise to prove

the adequacy of the design. The maximum temperature rise at the joints shall be less than the specified temperature rise for the busbars.

4.2.13.6.8 Clamps and Hardware The busbar clamps and insulators shall be designed to withstand

the forces due to momentary short circuit current. They shall permit free longitudinal movement of the busbars during expansion and contraction. The material of the clamps shall be aluminium alloy. Suitable copper or aluminium spacers shall be provided wherever necessary.

All bolts, nuts and lock washers used in the bus assembly shall be

of high tensile steel, plated for corrosion resistance. Suitable splice plates and bimetallic connectors shall be provided

wherever necessary.


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4.2.13.6.9 Disconnecting Links Disconnecting links with rating same as that of the main busbars

shall be provided in the run of the bus duct to facilitate disconnection of the bus bars during testing and maintenance. The separation of the busbar sections with the bolted links removed shall be sufficient to withstand the rated voltage of the busduct. Details of disconnecting links shall be furnished by the manufacturer. The minimum number of disconnecting links shall be provided as shown in the enclosed drawings

4.2.13.6.10 Shorting Links Shorting jumpers, for the purpose of drying out the equipment

before commissioning or for carrying out short circuit test on the equipment, rated for the main bus current shall be supplied for shorting the busduct at a location, adjacent to the disconnecting links.

The shorting links shall have drilling dimensions matching those

of the main bus disconnecting links. Suitable supporting structures and support insulators for the shorting links if necessary shall also be offered.

4.2.13.6.11 Phase Barriers 4.2.13.6.12 The phase barriers shall be of the material shall be same as that

of the busduct enclosure material. 4.2.13.6.13 Insulated phase barriers, when specified, shall be made of non-

hygroscopic insulating material such as fibre glass. 4.2.13.7 Bus Support Insulators 4.2.13.7.1 Within the busduct the bus shall be mounted and supported on

insulators. The insulators shall be mounted on resilient pads provided in the bus enclosure.

4.2.13.7.2 Material The insulators shall be of porcelain. 4.2.13.7.3 Mechanical Strength The insulators shall possess sufficient mechanical strength to

withstand the forces due to momentary short circuit currents of magnitude detailed in this specification. The spacing of the bus


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insulators shall be decided giving due factor of safety. 4.2.13.7.3 Electrical Strength As a consequence of current loading and variation in external

temperatures in the external sections of the busduct, condensation of moisture may take place on the surface of the insulators. Hence the insulators shall have a high creepage distance and a withstand voltage rating sufficient to provide specified insulation under highly humid conditions.

4.2.13.8 Wall Frame Assembly and Seal-off Bushings 4.2.13.8.1 Seal off Bushings The busduct shall be equipped wherever necessary with baffle

or seal off bushings to prevent interchange of air at different temperatures. The seal off bushings shall be flanged type.

4.2.13.8.2 Material The insulator for wall frame assembly and seal off bushings

shall be of porcelain. Also the bushings shall be designed for thermal expansion / contraction due to temperature differential for outdoor / indoor use.

4.2.13.8.3 Mechanical Strength The insulator shall withstand the maximum short circuit forces

under fault conditions specified in this specification. The insulator material shall not deteriorate under normal operating temperatures or due to temperature rise under fault conditions.

4.2.13.8.4 Electrical Strength The electrical properties of the insulator shall be in conformity

with this specification. 4.2.13.8.5 Phase Clearances The minimum phase to phase and phase to earth clearances of

busbars within the enclosures shall be as follows: Phase to Phase : Not Applicable Phase to Earth : 120 mm


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4.2.13.9 Busduct Supports 4.2.13.9.1 Material The supporting structure shall be fabricated from standard steel

sections and shall be hot dip galvanised after fabrication. 4.2.13.9.2 Mechanical Strength The supporting structures shall be designed to withstand the dead

weight of the busduct and also the short circuit forces under maximum fault conditions and also the wind load and forces due to seismic accelerations as per relevant Indian Standards. Calculations shall be furnished to substantiate the above and shall be subject to the PURCHASER / CONSULTANT's approval.

4.2.13.9.3 Accessories and Hardware The supporting structures including supporting members, brackets,

hangers, longitudinal beams, channels, nuts, bolts, insulating pads, insulating washers and all other hardware which are necessary for erection and support of the entire busduct installation. All the accessories and hardware of ferrous material shall be hot dip galvanised.

4.2.13.9.4 Earthing Each supporting structure shall be securely connected at two points

to the station earthing bus. All necessary hardware, such as clamps, connectors etc. required for this purpose shall be furnished by the vendor.

4.2.13.9.5 Markings All components of the busduct along with the supporting structure

shall be distinctly marked for erection in accordance with the erection drawings to be prepared and furnished by the vendor. These marks shall be made in a manner as not to be obliterated and erased in transit or to damage the galvanising of the busduct or the supporting structure.

4.2.13.10 Miscellaneous 4.2.13.12.3.5 Studs, nuts, bolts and tapped holes shall conform to the relevant

standards. Only hexagonal nuts shall be used. All bolt holes shall be spot faced for nuts.


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4.2.13.10.2 Castings and forgings shall conform to respective material specifications and shall be free from flaws. They shall be machined true as per good workshop practice. Welding shall be performed in accordance with relevant standards.

4.2.13.10.3 All threaded pipe connections and fittings, pipe flanges and tube

fittings shall comply with relevant standards. 4.2.13.11 Design Requirements of Busduct 4.2.13.11.1 The bid shall contain design calculation in support of the following

parameters of the busduct design:

a) Sizing of the busbars vis-a-vis thermal capability to withstand rated continuous current and three seconds short time current.

b) Spacing of the insulators vis-a-vis mechanical strength

to withstand forces due to momentary short circuit current.

c) Heat loss and temperature rise calculations for

conductor and enclosure. 4.2.13.12 Space Heaters & Silica gel breathers 4.2.13.12.1 The busduct shall be provided with space heaters of adequate

capacity to maintain the internal temperature above the dew point to prevent moisture condensation within the busduct. The space heaters shall be rated for 240V single phase, 50 Hz AC supply. The space heater shall be automatically controlled by differential thermometers.

4.2.13.12.2 Adequate number of silica gel breathers shall be provided in the

busduct. 4.2.13.12.3 Tests and Test Reports 4.2.13.12.3.1 The following type and routine tests certificates shall be

conducted on representative section of the bus assembly. The bus assembly tested shall include bolted connections and flexible connections. The tests shall be conducted as per standards indicated in this specification.

4.2.13.12.3.2 Type Tests

a) One minute power frequency withstand voltage test.


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b) Impulse voltage withstand test. c) Temperature rise test of bare black matt painted conductors

and enclosures. d) Dynamic withstand test. e) Water tightness test. f) Air tightness test.

4.2.13.12.3.5 Routine Tests

The following routine test shall be conducted at the vendors shop:

a) One minute power frequency withstand voltage test. b) Water tightness test. c) Air tightness test.

4.2.13.12.3.5 Test Report for Components Manufacturer's type and routine test certificates shall be

submitted for tests conducted as per relevant standards for the following components:

a) Insulators b) Seal-off bushings c) Bolted and flexible joints d) Busbars e) Enclosure material f) Galvanising of support structures

4.2.13.13 NGTR Cubicle 4.2.13.13.1 Standards The transformer and resistors covered by this specification shall

conform to the following and other relevant Indian Standards. Wherever Indian Standards are not available, they shall conform to relevant British or IEC Standards.

IS:3043 - Code practices for earthing. BS:162 - Electric power switchgear and associated apparatus

(applicable to Class-B apparatus in BS:162) IEEE-32 - Requirements, terminology and testing procedures for

Neutral grounding devices.


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IEC 129 - Alternating Current Dis-connectors and Earthing Switches

IEC 185 - Current Transformers IEC 529 - Classification of Degree of Protection

Wherever the stipulation in this specification are in conflict with any

of the above standards, the requirement under this specification shall be binding.

4.2.13.13.2 General Specifications The values and ratings of transformer and resistors shall be

designed to limit the earth fault current to 5 to 10 A depending on the capacitance of the system. The rating of transformer and resistor shall be designed to ensure the resistive component of fault current should not be lesser than residual capacitance current to avoid transient over voltage during earth fault. The resistive component should be at least more than 3 to 5 times of residual capacitance current. The BIDDER shall furnish the detailed calculation and basis for the rating selection of transformer and resistor for the specified rating.

4.2.13.13.3 Transformer and Resistors 4.2.13.13.3.1 The distribution transformer shall be of dry type and single

phase. The neutral current shall be limited to 100A during earth fault. The duty of the transformer shall be continuous during normal operating condition and for 30 seconds during earth fault condition. The transformer shall be designed with following capabilities:

- No saturation shall occur at all conditions. - To be suitable for withstanding over voltage caused due to

sudden load loss, field forcing condition and flux doubling conditions.

- The knee point voltage of the transformer primary shall be at least 1.3 times of line to line voltage of generator.

4.2.13.13.3.2 The resistor shall be of stainless steel edge wound type made up

of unbreakable, corrosion proof, jointless grids. It shall be suitable for use in monsoon tropical climate.

4.2.13.13.3.3 Resistors shall be designed for continuous duty during normal

operating condition and for 30 seconds during earth fault condition with temperature rise not exceeding 325 Deg.C over


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an ambient temperature of 50 Deg.C when the resistor is housed in a covered space.

4.2.13.13.3.4 Grids shall be mounted on steel rods insulated by special heat

resistant micanite paper tubes. Grid washers shall be of natural mica. Porcelain insulators shall be used to insulate the resistor element from body of the enclosure.

4.2.13.13.4 Isolator, Current Transformer, Potential Transformer and

Contactor 4.2.13.13.4.1 Manual link or manual isolator with vacuum contactor of

adequate rating, with sufficient auxiliary contacts shall be provided in the NGTR cubicle.

4.2.13.13.4.2 Current and potential transformers, as required for ground fault

protection shall also be provided. 4.2.13.13.4.3 These devices shall be rated for voltage class in accordance with

the recommendations of IEEE-32. 4.2.13.13.5 Enclosure 4.2.13.13.5.1 The resistors shall be housed in a metal clad enclosure suitable

for indoor installation, with minimum IP52 enclosure. 4.2.13.13.5.2 The enclosure shall have an arrangement for fixing it on

concrete foundations / floor and its thickness shall be not less than 3 mm.

4.2.13.13.5.3 The terminals for neutral and earthing connection shall be

housed in a separate vermin proof, weather proof compartment. It shall be possible to periodically clean the resistors after lifting

the top cover. It shall be possible to earth the cabinet or enclosure at two

places and for this suitable size of studs shall be provided on the sides.

4.2.13.13.6 Terminals 4.2.13.13.6.1 The connection between generator neutral and NGT shall be

done by means of bus duct / internal busbar connection, depending on the envisaged connection configuration.


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4.2.13.13.6.2 Suitable washers shall be provided between grid and terminals to maintain good contact.

4.2.13.13.6.3 The two ends of the resistor shall be brought out to

weatherproof bushing type terminals of adequate rating. Bolted type link shall be provided for isolating the resistor.

4.2.13.13.6.4 Bushing terminals shall be provided for neutral and earth

connections and they shall be housed in a metal clad enclosure. 4.2.13.13.7 Space Heater 4.2.13.13.7.1 Suitable space heater along with thermostat shall be provided

inside the resistor cabinet to prevent condensation of moisture. This shall be rated to operate from 240 V, 50 Hz supply. The terminals of the space heaters shall be brought out in a separate terminal box.

4.2.13.13.7.2 The cable used for space heater shall be aluminium conductor

PVC insulated armoured cable. The entire arrangement shall be complete with double pole switch, MCBs and thermostat.

4.2.13.13.8 Cooling The NGT shall be natural air cooled and any type of forced

cooling shall not be used. However, if required, louvers can be provided in the enclosure. But wherever the louvers are being offered it shall be completely guarded on inside with a fine wire mesh (holes less than 0.5mm) to make it vermin proof.

4.2.13.13.9 Name plate Marking The equipment shall have a nameplate located conspicuously

giving particulars, such as make, name of the equipment, rating and other relevant details.

4.2.13.13.10 Painting All surfaces to be painted shall be thoroughly cleaned, descaled,

made free from rust and given a priming and final coat of the paint, shade RAL 7032.

4.2.13.13.11 Inspection & Test Inspection shall be carried out by the PURCHASER /

PURCHASER’s representative and the following tests shall be conducted:


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- Measurement of resistance value at room temperature

by Kelvin Double Bridge. - One minute power frequency high voltage withstand

test shall be as per applicable voltage. 4.2.13.13.12 Heat Run Test The test shall be conducted by passing the rated current for

rated time on the complete assembly or by any method mutually agreed upon.

4.2.13.13.13 Test Certificates Test certificates of the equipments shall be furnished at the

time of inspection. 4.2.13.14 LAVT Cubicle 4.2.13.14.1 Standards

IEC:71 - Co-ordination of Insulation IEC:99 - Lightning Arrestors IEC:18 - Potential Transformers

IEC:52 - Classification of Degree of Protection

4.2.13.14.2 Design Requirements 4.2.13.14.2.1 The cubicle shall house Potential transformers required for

metering, protection, synchronisation and excitation system sensing..

4.2.13.14.2.2 Surge capacitors and Lighting arrestors required for surge

protection of the generator shall be housed in this cubicle. 4.2.13.14.2.3 The surge capacitors shall conform to the latest IS:2834 and

shall be rated 0.25 µF. The capacitors shall be suitable for indoor mounting and shall be provided with built in discharge resistor.

4.2.13.14.2.4 The lightning arrestors shall be heavy duty indoor station class

gapless metal oxide type suitable for repeated operation to limit voltage surges on alternating current power circuits and


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to interrupt power follow current. The arrestors shall conform to IEC 99-4. The nominal discharge current of lightning arrestor shall not be less than 5 kA.

4.2.13.14.2.5 The SUPPLIER to submit design back-up details for selection

of PT, LA and SC ratings. 4.2.13.14.3 Construction Features 4.2.13.14.3.1 The cubicle shall be simplex type. 4.2.13.14.3.2 The cubicle shall be sheet steel enclosed dust and vermin proof

type. The cubicle shall be floor mounting, free standing and suitable for busduct entry. The enclosure shall be of cold sheet of 3 mm thick for front and back and 2.5 mm thick for rest. Type of enclosure shall be IP 52.

4.2.13.14.3.3 The doors and openings shall be provided with neoprene gaskets. 4.2.13.14.3.4 Cubicles shall be suitable for top busduct entry. 4.2.13.14.3.5 All mounted equipment inside the cubicle shall have identification

tags of self sticking PVC tapes, in addition identification number shall be painted on cubicle wall to give permanent identification mark.

4.2.13.14.3.6 All wiring shall be done by PVC insulated 1100 V grade 2.5 mm

stranded copper cable. Each wire shall be identified at both ends by means of PVC ferrules.

4.2.13.14.3.7 Minimum 20% spare terminals shall be provided more than one

wire shall not be connected in any terminal. All terminals shall be stud type.

4.2.13.14.3.8 All busbars shall be sleeved type with colour coding at each end. 4.2.13.14.3.9 The PTs shall be of fully drawout type and both the primary and

secondary shall get isolated and earthed through scrapping earth. 4.2.13.14.3.10 PT’s primary shall be with uniform insulation. 4.2.13.14.3.11 The PTs shall be protected with HRC fuses on primary. MCBs

shall be made available on secondary side for circuit protection. 4.2.13.14.4 Painting


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After preparation of the under surfaces, with two coats of primer suitable for epoxy paint the cubicle shall be spray painted with two coats of final epoxy paint. Colour shade RAL 7032, with glossy finish. All unpainted steel parts shall be cadmium plated or suitably treated to prevent rust corrosion.

4.2.13.14.5 Earthing A continuous earth bus running along the full length of cubicle

shall be provided. Suitable arrangements shall be provided at each end for connection to main earthing grid.

4.2.13.14.6 Space Heater Anti condensation space heater shall be provided along with

thermostat to keep the cubicle temperature above ambient. 4.2.13.14.7 Test

The PTs shall be fully tested for 35 kV as per IS:3156. Lightning arrestors and surge capacitors to be tested as per relevant IS standards.

Following tests shall be carried out:

a) Checking of correctness of wiring of circuit b) High voltage test. c) I.R value test. d) Routine tests.

4.2.13.15 Sealed TVM Cubicle 4.2.13.15.1 The trivector meter shall be of digital type, class 0.2S with ABT

feature. The meter shall be suitable for 3 Phase, 4 wire system. The meter shall also be provided with RS 485 communication port with MODBUS RTU protocol and software.

4.2.13.15.2 The TVM shall be base mounted type and shall be provided

with the arrangement of sealing. The cubicle shall be provided with a door and view glass. This cubicle shall also be suitable for wall mounting.

4.2.13.16 Current and Potential Transformers 4.2.13.16.1 Current and potential transformers, for protection, metering &

controls shall be provided, in generator terminals, NGTR / LAVT


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cubicles, 11 kV switchgears and busducts, depending on the envisaged system.

4.2.13.16.2 Standards

IS:2705 & IEC:185 - Current Transformers IS:3156 & IEC:186 - Potential Transformers

4.2.13.16.3 The current transformer will be epoxy cast, bar primary, dry

type unit confirming to IS / IEC. The current transformer shall be designed to withstand the thermal and magnetic stresses resulting from the maximum short circuit current. The accuracy class for metering shall be 0.2 and protection shall be 5P20 & PS. The accuracy class for the dedicated CT for open access metering shall be 0.2S. For class PS core CTs, the knee point voltage shall match with the requirements of the connected relays. Care shall be taken to ensure that the matching CTs are properly matched for knee point voltage & magnetising current requirements; and preferably sourced from same manufacturer. All CTs shall be provided with not more than two cores and shall be suitable for 120% rated current, continuously.

4.2.13.16.4 The potential transformers will be single phase, epoxy cast, dry

type units. Potential transformer will be protected on primary by HRC fuses and secondary side by MCBs. The accuracy class for the dedicated PT for open access metering shall be 0.2. The accuracy class for Metering 0.2 and protection 3P. Voltage factor for the PTs shall be 1.2 times continuous and 1.9 times for 8 hours.

4.2.13.16.5 As the PTs are intended to be in service in unearthed system

and to avoid ferro resonance effect, the BIDDER shall envisage a suitable method to mitigate the above effect. A detailed write-up on the proposed method shall be furnished for CONSULTANT’s review.

4.2.14 SPECIFICATION FOR DC STARTER PANEL, DCDB AND ELECTRIC MOTORS

4.2.14.1 Panel Construction 4.2.14.1.1 The distribution board and starter panel shall generally conform

to the following standards:


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IEC-439 & IS:8623 - Specifications of Low Voltage Switchgear & Control gear Assemblies

IEC-947 & IS:13947 - Specification of Low-Voltage IS:13947 Switchgear & Control gear

IEC-269 & IS:9224 - Low voltage fuses IEC-144 & IS:2147 - Degree of protection of enclosure for low

voltage switchgears and control gear IE rules, guidelines, regulation of CEIG 4.2.14.1.2 The panels shall be dust, damp & vermin proof construction,

sheet steel clad totally enclosed, compartmentalized, floor mounted, self standing type with access from front & back by means of hinged doors. The panels shall have bottom entry provisions and shall be natural cooled.

4.2.14.1.3 The panels shall be fabricated with 2.0 / 2.5 mm thick sheet

steel and structural steel. It shall be free-standing with suitable louvers for ventilation and must be suitable for use in tropical climate. Hinged doors shall be provided at the front and back where required.

4.2.14.1.4 Inter panel sheet steel barriers shall be provided. The sheet

steel used for fabrication shall be thoroughly cleaned and degreased to remove mill scale, rust, grease and dirt. Fabricated structures shall be pickled and then rinsed to remove any trace of acid.

4.2.14.1.5 All metal surfaces shall be chemically cleaned, degreased and

pickled in acid to produce a smooth surface, free of scale, grease and rusts. After cleaning, phosphating and passivation treatment, the surface shall be given two (2) coats of zinc rich epoxy primer. The assembly shall be finished with two coats of epoxy paint in pebble / flint grey shade RAL 7032.

4.2.14.1.6 Reverse engraved name plates shall be provided for the panels

and all module sections. 4.2.14.1.7 All fuses shall be provided inside the panel. All fuses shall be

link type. Diazed fuses will not be acceptable. Terminal blocks shall be `Elmex' type.

4.2.14.1.8 All potential free metallic parts shall be earthed with soft drawn

copper conductor. The main earth connection shall be brought out to two terminals for connection to station earthing system.


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4.2.14.1.9 All live parts shall be properly shrouded. This shall ensure complete safety to personnel intending routine maintenance by opening the panel doors. Busbars shall be colour coded. All the equipment inside the panel shall have suitable name plates.

4.2.14.2 EOP & JOP Starter Panel

4.2.14.2.1 DC starter panel for control of EOP & JOP DC motor shall be

provided, as part of the DC distribution board. A spare feeder with complete starter modules shall be provided in the DCDB.

4.2.14.2.2 DC starter shall have switch fuse unit for short circuit protection.

Overload relay shall be provided for alarm purpose. The starter shall also have field failure protection for the motor.

4.2.14.2.3 DC contactor used in the starter panel shall be provided with

adequately rated magnetic blow out coil for effective arc quenching.

4.2.14.2.4 DC resistance in suitable steps, but not less than three (3), shall

be provided. 4.2.14.2.5 For interfacing with PURCHASER’s DCS, the following signals

shall be hooked-up to a marshalling compartment in the distribution board :

- EOP & JOP starter ON / OFF status - EOP & JOP motor over load relay operated - EOP & JOP motor field failure relay operated - Start & Stop command from DCS

4.2.14.3 DC Distribution Board

4.2.14.3.1 Two (2) numbers of DCDB with each of the DCDB sized to cater

100% of the TG loads shall be provided. Bus coupler for interconnection shall also be envisaged. The DCDB shall be connected to its own dedicated battery bank.

4.2.14.3.2 The DC distribution boards and for each TG set shall have the

following feeders, in addition to the feeders to meet BIDDER’s requirements:

a) Two (2) numbers 63A FSU feeders b) Ten (10) numbers 32A FSU feeders

4.2.14.3.3 The distribution board shall have the following meters / relays /

transducers:


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- Ammeter and Voltmeter at the incomer - Ammeter for all outgoing feeders - Current and Voltage transducers at the incomer - Current transducer for EOP starter - Bus under voltage and over voltage relay

4.2.14.3.4 For interfacing with PURCHASER’s DCS, the following signals

shall be hooked-up to a marshalling compartment in the distribution board

- ON and OFF status of incomer and all outgoing feeders - Bus under voltage and over voltage signals - (4-20) mA signals from all transducers

4.2.14.4 AC Electric Motors 4.2.14.4.1 All the auxiliaries shall be suitable for 415 V (3 Phase 3 Wire

system), without neutral. 4.2.14.4.2 All the motors shall be of squirrel cage type. 4.2.14.4.3 Starting Methods of Motors shall be as below unless otherwise

specified elsewhere in this document:

- Motors shall be suitable for DOL starting unless otherwise specified elsewhere in this document.

- All VFD application motors shall be capable of starting with

DOL as bypass starting arrangement.

4.2.14.4.4 System fault levels to be considered for design of the equipment shall be 65 kA for one second at 415V system.

4.2.14.4.5 The Rated voltage shall be 415V, three phase for motors of rating

0.37 kW and above. It shall be 230V, single phase for motors of rating below 0.37 kW.

4.2.14.4.6 All AC motors driving various auxiliaries of the unit shall be

designed to operate in humid atmosphere with a maximum ambient temperature as indicated in project information. The motors shall be of squirrel cage induction machines with a degree of protection IP54 for indoor application and shall conform to IS:325 / IEC-60034. Motors for outdoor application shall be IP55 degree of protection with sheet steel canopy.


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4.2.14.4.7 The motor windings shall be provided with Class F insulation. The motors shall be suitable for ± 10 % voltage variation (on rated voltage) and 50 Hz ± 5% frequency variation (subject to combined variation of 10%) with maximum temperature rise limited to limits of ‘Class-B’ insulation.

4.2.14.4.8 All the continuous duty motors shall be of ‘energy efficient’ (IE2

range type for motor rating upto 55 kW and IE3 range type for motor rating 75 kW & above), with efficiency figure at 100% load is not less than the efficiency value as indicated in the ‘Table for Motor Efficiency’. Motor efficiency between 60% to 100% load shall be constant.

4.2.14.4.9 Motors of rating 30 kW and above shall be provided with space

heaters. 4.2.14.4.10 Terminal box to be rotatable by 4 x 90 Deg. Higher rated motors

shall be provided with extension terminal box to receive the aluminium cables of following sizes to avoid cramping of the cable in the terminal box: a. 90-110 kW : 2-3Cx185 Sq.mm b. 132-180 kW : 2-3Cx300 Sq.mm c. 200-280 kW : 4-3Cx185 Sq.mm d. 300-440 kW : 4-3Cx300 Sq.mm e. 425-600 kW : 6-3Cx300 Sq.mm f. 625-720 kW : 8-3Cx300 Sq.mm

4.2.14.4.11 The terminal boxes shall be capable of withstanding the maximum system fault current for a duration of at least 0.25 second. Terminal boxes mounting shall be tapered and not on top.

4.2.14.4.12 Motors shall be suitable for being switched on to a solid main even

at phase opposition at a maximum residual voltage of 50% i.e. the motor shall be capable of withstanding 150% of the rated voltage.

4.2.14.4.13 Motors shall be capable to start and run-up at a minimum of 80%

of rated voltage at its terminals with the driven mechanism / equipment connected.

4.2.14.4.14 Motors shall be capable of operating satisfactorily at full load

for 5 minutes without injurious heating with 75% of the rated voltage at its terminals.

4.2.14.4.15 Brake away torque, pull-up torque and pull-out torque shall be

properly coordinated with the speed torque characteristics of the driven equipment, and the BIDDER shall submit the characteristic curves interposing motor & driven equipment curves.


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4.2.14.4.16 Hot withstand time of the motor shall be at least 10 seconds longer than the starting time under rated load conditions, for the motors where the starting time is more than 30 second. For motors with lesser starting time, a margin of 5 seconds shall be ensured. The starting time of the motors shall be mentioned in the document.

4.2.14.4.17 Starting current of the motor shall be less than or equal to 600 %

of the rated current. 4.2.14.4.18 Continuous duty motors shall be capable of three equally spread

starts per hour under normal condition or two starts in quick succession from cold or one hot start, under rated load conditions.

4.2.14.4.19 All bearing to bee of lubricated anti-friction type. No forced

lubrication acceptable. 4.2.14.4.20 Motor to be of Totally Enclosed Fan Cooled (TEFC) design. Cooling

fans shall be shaft mounted type only (No additional cooling motor shall be provided).

4.2.14.4.21 Specific requirements of LV general duty motors

- Rated voltage shall be 415V. - Motors shall be provided with RTDs/BTDs as indicated in the table below:

SL Motor Rating RTDs BTDs

1. 30 – 90 kW One (1) per phase Not Required

2. 110 kW and Above

One (1) per phase Two (2) Nos. (Drive End – 1 No. and Non-Drive End – 1 No.)

4.2.14.4.22 Specific requirements of motors intended for VFD application:

- Rated voltage shall be 415V. - Should be suitable for the selected IGBT based variable

frequency drive, and shall match with the drive in respects of over voltage / spikes generated by the drives.

- The windings shall be VPI treated and two coat enameled.

These motors shall be sized to operate satisfactorily under the lowest speed conditions. Operating speed requirement shall be as below:


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Fans : 50% to 100% Pumps : 50% to 100% Fuel feeders : 10% to 100%

- The motor windings shall be provided with Class H insulation

with maximum temperature rise limited to limits of ‘Class-B less 10 Deg C’ insulation.

- NDE bearings of motors of rating 110 kW and above shall be

insulated to prevent circulation of shaft currents. Manufacturer shall furnish details of bearing insulation.

- The BIDDER shall submit detailed calculations for checking

adequacy of the motor selected under extreme speed conditions, furnishing the selection chart of the motor manufacturer for VFD application.

- All variable frequency drive motors shall be provided with

embedded Thermistors / RTDs / BTDs for motors as indicated in the table below:

Sl Motor Rating Thermistors RTD BTD

1. 3.7 – 22 kW One (1) per phase

Not Required Not Required

2. 30 – 90 kW Not Required One (1) per phase

Not Required

3. 110 kW and Above

Not Required One (1) per phase

Two (2) Nos. (Drive End – 1 No. and Non-Drive End – 1 No.)

4.2.14.4.23 Inspection & Testing:

The following minimum tests shall be carried out on the motor to ensure its Successful operation as per the specification.

TESTS Up to 22 kW

30 kW to 55 kW

75 kW & above

Measurement of resistance of windings of stator and rotor

� � �

No load test to measure input power, current, speed and to determine no load losses and efficiency at full load

� � �


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Locked rotor readings of voltage, current and power input at a suitable reduced voltage

� � �

Reduced voltage running up test to check the ability of the motor to run up to its rated speed at no load.

� � �

Open circuit voltage ratio of stator and rotor windings (applicable for slip ring motors)

� � �

High voltage test � � �

Insulation resistance test � � �

Temperature rise test at limiting values of voltage and frequency variation.

(�) (�)

Vibration test (�) �

Noise level test (�) �

Momentary overload test (�) �

Full load test to determine the efficiency, power factor, and slip

(�) � �

Over speed test (�) (�)

Test for degree of protection (�) (�)

Test on insulation system (�) (�)

(�) – Test report of identical motor (frame, speed & kW) for having carried

out with in five years.

� - The tests shall be carried out in the motor.

4.2.14.4.24 lso the efficiency calculations by using the values of locked rotor test and full load test for all the motors of above 22kW shall be submitted.

4.2.14.4.25 All the routine and type tests shall witnessed and verified by

PURCHASER/CONSULTANT.


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4.2.14.4.26 TABLE FOR MOTOR EFFICIENCY

RATING 2 POLE 4 POLE 6 POLE 8 POLE

in KW 3000 RPM 1500 RPM 1000 RPM 750 RPM

0.37 70.2 73.0 69.4 66.8 0.55 74.0 78.0 72.0 71.1 0.75 77.0 82.5 74.6 73.8 1.1 82.8 83.8 77.3 76.2 1.5 84.1 85.0 79.6 77.9 2.2 85.6 86.4 82.2 80.5 3.7 87.5 88.3 85.1 83.0 5.5 88.6 89.2 86.8 85.1 7.5 89.5 90.1 88.1 86.4 9.3 90.0 90.5 89.3 87.3 11 90.5 91.0 89.7 88.1 15 91.3 91.8 90.5 89.0 18.5 91.8 92.2 91.3 89.8 22 92.2 92.6 91.8 90.2 30 92.9 93.2 92.6 91.5 37 93.3 93.6 93.0 91.9 45 93.7 93.9 93.4 92.4 55 94.0 94.2 93.8 92.8 75 94.6 94.7 94.2 93.5 90 95.0 95.0 94.5 93.9 110 95.0 95.2 94.6 94.3 125 95.3 95.5 94.8 94.6 132 95.3 95.5 94.9 94.7 160 95.5 95.8 95.2 94.9 200 96.0 96.2 95.2 95.3 250 96.0 96.2 96.0 95.5 300 96.0 96.3 96.0 95.5 350 96.2 96.5 96.2 95.7 440 96.5 96.8 96.5 96.0 450 96.7 97.0 96.5 96.1 500 & Above

97.0 97.2 96.6 96.2

NOTE :

- All efficiency figures are subject to IS Tolerance - Wherever ratings other than those mentioned in the above

table are used, the efficiency figure will be interpolated.


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4.2.14.5 DC Motors

4.2.14.5.1 Constructional features

- Industrial type, heavy duty, continuously rated, totally enclosed, generally designed and manufactured as per IEC:60034/1, BS:2613, IS:4722.

- Stator Yoke and Poles as well as armature shall be preferably of

fully laminated construction with low loss silicon steel sheet - Frame made of cast steel or thick rolled steel plates. - Shaft forged from special high tensile steel with tapered ends. - Brush holder to maintain constant brush pressure regardless of

brush wear and to ensure spark less commutation at top speeds and over-load.

- Machine feet cast integral with the body as integral foot

mounting construction. - Degree of protection for motor, bearing housing and terminal box

shall be IP54.

4.2.14.5.2 Bearings and bearing Lubrication

- Motors with shaft heights upto 225 mm, shall be life time greased.

- Motors with shaft heights 250 mm and above, shall be equipped

with regreasing devices and grease quantity controllers. 4.2.14.5.3 Terminal Box

- To be dimensioned adequately for receiving aluminium cable. - To be provided on the right hand side as viewed from the drive

end. - Shall be rotatable by 4 x 90 Deg.

4.2.14.5.4 Cooling

- TEFC


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4.2.14.5.5 Quality of operation

- Same as specified for low voltage squirrel cage induction motors 4.2.14.5.6 Electrical design

- Operation from DC starter panel - Operation shall be unaffected by voltage or current ripples. - Overload Capacity : Minimum 160% frequently repeated

momentary load for 15 seconds. - Over speed : Capable of withstanding and over speed of 20%

above rated maximum field weakening speed. - Insulation: Shall be provided with class F insulation throughout

the stator and rotor windings but designed for temperature rise (as measured by resistance method) corresponding to that of class B insulation.

4.2.15 SPECIFICATION FOR FEED WATER HEATERS

HP heater #1 & #2 4.2.15.1 Process Parameters 4.2.15.1.1 Feed water flow (tube side) : As per HMBD 4.2.15.1.2 Feed water inlet temperature : As per HMBD 4.2.15.1.3 Required Feed water outlet temperature : 190 Deg.C ( For HP Heater

#1) 235 Deg.C (For HP Heater

#2) 4.2.15.1.4 Feed water inlet operating pressure : As per HMBD 4.2.15.1.5 Extraction Steam Parameters 4.2.15.1.5.1 Steam Pressure : As per HMBD 4.2.15.1.5.2 Steam Temperature : As per HMBD


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4.2.15.2 Design Parameters 4.2.15.2.1 Tube side design pressure : The same shall be cold

shutoff head of the BFP

4.2.15.2.2 Shell design pressure : Supplier to specify 4.2.15.2.3 Design temperature for shell side : Supplier to specify 4.2.15.2.4 Design temperature for tube side : Supplier to specify 4.2.15.2.5 Allowable pressure drop on tube side : 0.8 kg/cm2

LP heater

4.2.15.3 Process Parameters 4.2.15.3.1 Turbine condensate (tube side) : As per HMBD 4.2.15.3.2 Turbine condensate inlet temperature : As per HMBD 4.2.15.3.3 Turbine condensate outlet temperature : As per HMBD

4.2.15.3.4 Turbine condensate inlet operating pressure : As per HMBD 4.2.15.3.5 Extraction Steam Parameters 4.2.15.3.5.1 Steam Pressure : As per HMBD 4.2.15.3.5.2 Steam Temperature : As per HMBD 4.2.15.4 Design Parameters 4.2.15.4.1 Tube design pressure : cold shut off pressure of

CEP 4.2.15.4.2 Shell design pressure : Supplier to specify 4.2.15.4.3 Design temperature for shell side : Supplier to specify 4.2.15.4.4 Design temperature for tube side : Supplier to specify 4.2.15.4.5 Allowable pressure drop on tube side : 0.8 kg/cm2


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4.2.15.5 Other Requirements 4.2.15.5.1 Orientation of feed water Heater : Horizontal 4.2.15.5.2 Location : TG Hall. 4.2.15.5.3 Drain cooler section required : Supplier to specify 4.2.15.5.4 Maximum tube velocity : 3.0 Mtrs/Sec 4.2.15.5.5 Heat Load (Design) : Shall be designed with

5% margin over and above the maximum expected heat duty

4.2.15.6 Material of Construction 4.2.15.6.1 Tube material

HP heater : Stainless Steel to ASME SA 213 Gr.TP 304

LP heater : Stainless Steel to ASME SA 688 Gr.TP 304 4.2.15.6.2 Tube plate material : Carbon Steel to ASME SA 516 Gr.70 or equivalent 4.2.15.6.3 Shell material : Carbon Steel to ASME SA 516 Gr.70 or equivalent 4.2.15.6.4 Channel / channel cover : Carbon Steel to ASME SA 516 Gr.70 or equivalent 4.2.15.6.5 Flange material : Carbon Steel to ASME SA 516 Gr.70 or equivalent 4.2.15.6.6 Nozzle material : Carbon Steel to ASME SA 181 Gr. 1 4.2.15.6.7 Materials of baffles,tube : Commercial Quality Steel support plates, tie rods and spacers 4.2.15.6.8 Stud and stud bolts/nuts : SA 193 Gr.B7 or

equivalent SA 194 Cl.2H or

equivalent


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4.2.15.7 Accessories The Heater shall be supplied with the following minimum accessories.

Shell Relief Valve, Channel Relief Valve, Shell Vent Valve, Channel Vent Valve, Shell Drain Valve, Channel Drain Valve, Supports / Brackets, Tube Bundle Shield, Lifting Lugs, Thermal Insulation Clips, Alignment Dowels, Jack Screws, Name Plate, Earthing Cleats.

4.2.15.8 Design & Construction Requirements 4.2.15.8.1 General 4.2.15.8.1.1 The capability, size and design conditions for the feed water heater

shall be as specified. 4.2.15.8.1.2 The design shall have provision for complete drainage of both shell

and tube sides. Adequate drains in size and number on low points of heater shells and water inlet channels for proper drainage and/or supply of solutions during chemical cleaning process shall be included. The minimum size of nozzle shall be 50mm. Pneumatically operated level control valve with 100 % bypass same as main valve on the condensate line of both the heaters. Also a set of special tools and tackles shall be provided by the EPC contractor.

4.2.15.8.1.3 All connections to feed water heater 65 mm NB size and larger, shall

be welding-nozzle type with ends shop beveled, except where flanged joints are specified for removal of shell connection or removal of tube bundle. Connections 50 mm NB and smaller, shall be socket welded or screwed.

4.2.15.8.1.4 Heaters shall be provided with startup vent connections which will be

separate from the vent connections required for continuous operation.

4.2.15.8.1.5 The heater shall be designed for full vacuum conditions, on the steam

side. 4.2.15.8.1.6 Heaters shall be provided with name plates which shall include all

information required by the applicable regulations and codes. The necessary information shall be on a metal name plate permanently affixed to the heater and set off the surface by brackets so as to be readily visible after the equipment is insulated.

4.2.15.8.1.7 The feed water heater shall be furnished with instrument connections

for alarm, indication and control of drain level as specified.


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4.2.15.8.1.8 Corrosion allowance on all cast iron, carbon steel and low alloy steel parts shall not be less than 3.2 mm (0.125 in). A minimum corrosion allowance of 1.6 mm (0.0625 in) shall be added to the thickness of ferrous tubes. Where flanges like weld neck flanges are used, the corrosion allowance shall be applied to the inside flange diameter and the flange thickness shall be calculated with the inside diameter under corroded conditions. No corrosion allowance shall be required to be added to the thickness of non-ferrous tubes, external and internal bolting material, baffles and supports.

4.2.15.8.1.9 The feed water heater shall be provided with relief valves on the shell

and tube side. 4.2.15.8.2 Heater Shells 4.2.15.8.2.1 The shell shall be of longitudinally welded or seamless type. Of the

two, seamless shell is preferred. While offering seamless shell, the minimum wall thickness (nominal wall thickness less the tolerance ) less corrosion allowance shall be considered as available for design.

4.2.15.8.2.2 The shell cover shall be of forged or built-up welded construction.

The shell cover shall have a 2:1 elliptical, torispherical or spherical head. The shell cover shall be welded on to the shell in case of U-tube bundles. The thickness of the flat channel cover shall be measured at the groove made for receiving the pass partition wall. The channel cover shall be of either rolled plate or of forged construction. The pass partition plates shall be tightly welded in place and shall be structurally adequate to withstand normal plant operations such as start-up restarts, shutdowns and trip outs. Channels shall be so constructed that the tube side of the feed water heater shall be self draining through the tubes.

4.2.15.8.2.3 Jack screws of proper size and number shall be provided for breaking

the channel cover joint and shell cover joint. The jack screws shall have the same material specification as the bolting material.

4.2.15.8.2.4 Suitable forged bolts or drilled lugs shall be provided for channel

cover, shell cover, tube sheets, floating head cover for use in assembling and dismantling the unit. All bolt holes shall be spot finished for nuts.

4.2.15.8.2.5 Suitable insulation clips shall be welded to the shells in an appropriate

manner for the application of insulation at site. 4.2.15.8.2.6 One piece, metal jacketed or solid metal gaskets shall be used.

Mating surfaces shall not be exposed to fluid.


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4.2.15.8.3 Tubes 4.2.15.8.3.1 Tube MOC shall be as mentioned above. The tube bundle shall be

removable. The annular clearances between the tubes and the shell must be kept to a minimum to prevent the shell side fluid bypassing the bundle and to obtain full penetration of steam through the tube bundle for efficient heat transfer.

The tube to tubesheet joint shall be seal welded and fully rolled.

Tubes shall be expanded into the tube sheet for a length of tubesheet thickness minus 1/8 th inch (3.2 mm). Tube sheet shall be machined with two grooves for additional longitudinal load resistances. The tube rolling procedure shall be submitted for the OWNER's review and acceptance prior to the use.

4.2.15.8.3.2 U tubes when used, shall consist of one continuous bent tube. U

tubes welded at bends shall not be acceptable. Bends shall not have cracks, kinks or deformations. The minimum wall thickness required at any points, including bends, shall be in accordance with the specified codes. Due allowance shall be made for thinning of tubes during bending. Hot bending to form U tubes shall not be allowed.

4.2.15.8.3.3 All tubes and U-bends, shall conform to the requirements of latest

revisions of the codes and standards. 4.2.15.8.3.4 Stainless Steel 4.2.15.8.3.4.1 The stainless steel tubes shall meet the requirements of the

following paragraphs: 4.2.15.8.3.4.1.1 Minimum tube wall thickness of stainless steel tubes shall be

determined by standards and codes, but in no case shall be tube wall be less than 20 BWG average wall before bending. Straight tubes may be 22 BWG average wall.

4.2.15.8.3.4.1.2 Tubes shall comply with the requirements of the latest revision

of the specification indicated. In addition the following shall also apply.

a. The stainless steel tubes including bends shall be in

the heat treated condition. The bends shall be solution annealed after bending. Electric resistance heating is acceptable for heat treating the bends.

b. Finished tubes shall be annealed and pickled or passiv-

ated in a manner acceptable to the codes and standards.


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c. Lubricants, if used during the manufacturing processes (drawing, bending etc.) shall be chloride free (5 ppm maximum), completely water soluble and shall be removed entirely before heat treatment, welding and at completion of fabrication (before testing).

4.2.15.8.3.4.2 Tests Tests performed on stainless steel tubes shall be as follows: 4.2.15.8.3.4.2.1 Hydrostatic and non-destructive electric tests (eddy current

tests) shall be performed on each tube in accordance with ASTM A-450 or approved equivalent standards.

4.2.15.8.3.4.2.2 Each lot of tubes shall have a flare test with atleast two tests

per lot. The flare test shall be in accordance with ASTM Specification A-450 or any approved standard.

4.2.15.8.3.5 Adequate stainless steel impingement plates of 10mm (3/8")

minimum thickness shall be provided at all shell nozzles receiving steam to protect tubes against impingement and erosion attack. The impingement plate shall have double the area of the inlet nozzle and will be located on the tube bundle. Perforated impingement plates shall not be accepted.

4.2.15.8.3.6 The design of the feed water heater shall incorporate necessary vents

and baffles to avoid blanketing of the tube surface by stagnant pockets of non-condensible gases.

4.2.15.8.4 Tube Sheets, Baffles and Support Plates 4.2.15.8.4.1 Tube sheets shall be designed for the full design pressure acting

independently on either side. The tube sheet shall have grooves for receiving the pass partition wall and the web of the gasket. The effective tube sheet thickness shall be as measured at the bottom of the pass partition wall groove minus shell side corrosion allowance. The tube sheet shall be of rolled plate or forged and faces of the tube sheets shall be true before and after the tubes are rolled in. Suitable threaded holes for eyebolts shall be provided on the tube sheet to facilitate pulling and removal of the tube bundle.

4.2.15.8.4.2 The feed water heater shall be designed to prevent the superheated

steam at entry to the feed water heater from coming into contact with the tube plate and plate joint.

4.2.15.8.4.3 Tube nests shall be suitably baffled to prevent vibration and to obtain

uniform distribution of steam and free drainage of the condensate of


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the tubes. 4.2.15.8.4.4 Baffles and support plates shall be of rolled plates. All baffles shall be

designed to eliminate, as far as practicable, dead fluid spaces between adjacent passes. Baffles and support plates shall be provided with notches required for shutdown drainage or for removal of condensate where necessary. The number of tie rods and spacers used to retain the cross baffles and tube support plates shall be as recommended by specified codes. Spacers may be welded to baffles to stiffen the baffle assembly. Alternatively, the tie rods may be secured to end baffles by nuts which will be screwed on to the tie rod ends.

4.2.15.8.4.5 The complete assembly of tubes, tube support plates, baffles,

shrouds etc. shall snugly fit around the tubes and the shell interior to avoid short circuiting of shell fluid and permit unrestricted differential expansion.

4.2.15.8.5 Water Boxes

The water box or channel section of all heaters shall be of fabricated or forged steel construction. The water boxes shall be sufficiently deep and specially designed for efficient and smooth entry of water into the tubes and uniform distribution of feed water to all the tubes. Wherever required, stiffening sections shall be external to the water box in order to reduce the turbulence in the waterways to a minimum. Easy access to the interior of water box for inspection and maintenance shall be provided. The water box shall be fitted with relief valves and vent valves.

4.2.15.8.6 Flanges, Bolts, Nozzles and Pipes 4.2.15.8.6.1 All flanges shall have a minimum thickness as per code specified.

Forged and weld neck flanges shall be preferred. Main shell and channel flange joints shall be of tongue and groove type.

4.2.15.8.6.2 The minimum entrance area shall not be less than the inside area of

the inlet nozzle. All pipes used for nozzles shall be seamless. The nozzle wall thickness shall be calculated in accordance with codes specified. Nozzle openings shall be flanged. All nozzle flanges shall be capable of withstanding the maximum test pressure and shall have raised face.

4.2.15.8.6.3 Nozzles shall project a minimum of 150 mm outside the insulation. 4.2.15.8.6.4 External Forces on Major Pipe Connections The heater including its supports, shall be capable of withstanding


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safely the forces and moments transmitted from any of the interconnecting piping.

Feed water heater channel (water or tube side) connecting nozzles to

the Feed water piping shall be capable of withstanding the forces and moments transmitted from the piping on the basis that the piping may be fully stressed under the rules of ASME B 31.1 Power Piping Code except that the supplier may limit the forces and moments individually or severally.

4.2.15.9 Fabrication Tolerances 4.2.15.9.1 Dimensional tolerances shall be as per TEMA standards. The shell

sections shall be sufficiently true to roundness so that the difference between the maximum and minimum measured inside diameter at any cross section along the length of the shell shall not exceed 3.2 mm.

4.2.15.9.2 The tolerances for the finished tube holes in tube sheets shall not

exceed the limits prescribed by TEMA. Care shall be exercised to ensure 96% or more of tube holes are within prescribed limits to avoid over or under expansion when mechanical means of expansion of tubes are employed.

4.2.16 List of Motorized valves

The OWNER wishes to go in for automation of the plant operation to the maximum extent possible. This calls for motor operation for a few of the important valves. Notwithstanding any thing mentioned to the contrary, elsewhere in these specifications, the following gives the list of minimum number of motor operated valves (For additional scope for Motorized Valve also refer P & IDs). - Vacuum breaker isolation valve (1 no/ TG) - LP extraction line (1 no/ TG) with integral bypass (inching type) - HP 1 and 2 extraction steam line (2 nos/ TG) with integral bypass (inching type)

- Upstream isolation valve in pneumatically operated control valve (main line) The motorized valves open / close time shall be suitable for the application. However, motor operated valves used in the HP heaters isolation shall have a closing time of maximum 12 seconds.