ACKNOWLEDGMENT

The training opportunity I had with NHPC LTD. was a great chance for learning and professional development. Therefore, I consider myself as a very lucky individual as I was provided with an opportunity to be a part of it. I am also grateful for having a chance to meet so many wonderful people and professionals who led me though this training period.

Bearing in mind previous I am using this opportunity to express my deepest gratitude and special thanks toMr. Altaf Hussain who in spite of being extraordinarily busy with his duties, took time out to hear, guide and keep me on the correct path and allowing me to carry out my project at their esteemed organization and extending during the training.

It is my radiant sentiment to place on record my best regards, deepest sense of gratitude to Mr. Pingal Kispotta (Sr. Manager),Mr. S.C Behera (Dy. Manager) for his careful and precious guidance which were extremely valuable for my study both theoretically and practically.

I perceive as this opportunity as a big milestone in my career development. I will strive to use gained skills and knowledge in the best possible way, and I will continue to work on their improvement, in order to attain desired career objectives.

Sincerely,

NEERAJ PRASAD

DARJEELING POLYTECHNIC INSTITUTE

3RD YEAR ELECTRICAL ENGINEERING

TABLE OF CONTENT

1. Company Profile

2. Introduction to hydroelectric power plant

3. Two main parts of TLDP-3 Barrage Control Room

4. Primary cooling Floor

5. Secondary Cooling Floor

6. Turbine Floor

7. Generator Floor

8. Machine Hall

9. Control Room

10. Transformer Gallery

11. GIS(Gas Insulation Substation)

12. Transmission

13. Conclusion

COMPANY PROFILE

Teesta Low Dam project-3 was entrusted to NHPC on 15 Nov. 2000. It stands at 27.00280, 488.44098 on river Teesta in Darjeeling district of West Bengal located at 42KM from Siliguri via NH-31. Called the run of the river project as this dam function is only to generate electricity ad not store water in the reservoir.

Location On river Teesta in Darjeeling dist.

Approach Nearest Rail Head- New Jalpaiguri & Nearest Airport- Bagdogra

Capacity (4*33)MW or 132 MW

Annual Generation 594.07 MU (90% dependable year)

Project Cost Rs. 768.92 crores

Teesta Low Dam Project-3 was constructed by the infrastructure company “HINDUSTAN CONSTRUCTION COMPANY LIMITED” and cost 768crores under NHPC. It has a 32.5 m high, 140 m long concrete barrage and has the capacity to generate 600 MW of power annually.

It comprises of four units of 33 MW each. Unit 1 & 2 got commissioned in January 2013, Unit 3 started commercial operations in April 2013 while Unit 4 in May 2013.

The project received the environment ministry nod in July 2003. Due to geological conditions and contractual problems, NHPC has missed the target of commissioning the power plant within the 11th plan.

INTRODUCTION TO HYDROELECTRIC POWER PLANT

IN Hydroelectric power plants the potential energy of water stored at a height is converted into electrical energy

The Hydroelectric power depends on:-

1. Head of water

2. Discharge of water

Total power that can be generated is:-

P=(0.736*W*H*Q*n/75) kW

Basin Name Hydroelectric basin MDDL for power house Water Level Variation between

FRL and MDDL of Power plant (m) Annual Design energy (MU)

Firm Power (MW)

No. of Turbines/Units (MW)

Capacity per turbine (MW)

Total Installed Capacity (MW) Sum of IC of all turbines

Type of Turbines

Rated Head (Net RTD) (m)

Specific Speed (MKu)

Number of Penstocks

Length of Penstock (m)

Size of Penstocks

Design discharge through

Brahmaputra Brahmaputra basin 203m 5

594.07 24.2 4 33

132

Kaplan

21.34 548.2

4 45 7

173.4

TWO MAIN PARTS OF TLDP-3

1. BARRAGE In TLDP-3 140m long Barrage has seen constructed across river Teesta at 27 Miles from

Rambi The height of the Barrage is 32.5 m and having 7 gates

Barrage

Intake Gate

ArmRadial Gate

Penstock

FISH LADDER GATE

Capacity 10 MT Lifting And Lowering Speed 0.5 M/Max Lift of Gate 7.5 M

TRASH SCREEN BULK HEAD GATE

Capacity 2 MT Lifting And Lowering Speed 0.25-0.35 M/Max Lift of Gate 7.5 M

There are basically four types of power plants: - Pelton turbines - It is impulse turbine which is normally used for more than 250 m of water

head.

Francis - This is a reaction turbine which is used for head varying between 2.5m to 450m

Kaplan – It is propeller type of plant with adjustable blades which are used for heads varying between 1.5 m to 70 m

Propeller – It is used for head between 1.5 to 30 m

Tubular – This is used for low and medium height projects. Normally for head less than 15 m

Fish Ladder GateStop Log

2. POWER HOUSE TLDP-3 consists of a underground and surface power house

POWER HOUSE OF TLDP-3 CONSISTS OF:-

PRIMARY COOLING FLOOR SECONDARY COOLING FLOOR TURBINE FLOOR GENERATOR FLOOR MACHINE HALL CONTROL ROOM TRANSFORMER GALLERY GIS(GAS INSULATION SUBSTATION)

How energy is generated in Hydroelectric Power Plant?

A hydroelectric power plant consists of a high dam that is built across a large river to create a reservoir, and a station where the process of energy conversion to electricity takes place.

The first step in the generation of energy in a hydropower plant is the collection of run-off of seasonal rain and snow in lakes, streams and rivers, during the hydrological cycle. The run-off flows to dams downstream. The water falls through a dam, into the hydropower plant and turns a large wheel called a turbine. The turbine converts the energy of falling water into mechanical energy to drive the generator After this process has taken place electricity is transferred to the communities through transmission lines and the water is released back into the lakes, streams or rivers. This is entirely not harmful, because no pollutants are added to the water while it flows through the hydropower plant.

PRIMARY COOLING FLOOR

Located at an elevation of 176.5 M It is open circulating System The primary cooling floor is associated with the cooling of generator coolant. This floor

employs motors which brings in raw water and pumps it to the secondary cooling floor where the generator coolant is cooled through heat exchangers

The pumps shall be centrifugal type directly driven by 3 phase 415v AC squirrel cage induction motor. The pump motor shall be mounted on common base plate. The impeller of pumps will be made in stainless steel, pump casing in steel casting and shaft in stainless steel. The discharge capacity of each pump shall meet the total requirement of cooling water of one unit.

It is open loop system TOTAL NO OF PUMP IS 6

1. 4 SEPARATE PUMP FOR 4 DIFFERENT UNIT2. 2 COMMON PUMP in case of any motor failure

RATING OF THE MOTOR 55KW(75HP) NO OF DUPLEX STRAINER 6 SPEED OF THE MOTOR 1475 EFF 93 F AMB 51 LENGTH OF RAW WATER HEADER

76.5M

LENGTH OF DELIVERY WATER HEADER

70 M

WHEN WE NEED MAINTANCE OF FILTER WITHOUT OPENING IT THEN WE USE MOTORIZING WHICH IS CONNECTED TO VALVE

WE GIVE SUPPLY WATER THROUGH DRILL LINE FLOW METER :- 600 1/MIN FLOW METER IS USING TO CHECK WHETHER THE WATER IS FLOWING OR

NOT 3KG OR 4 KG PRESSURE OF WATER IN PRIMARY

AUXILARY SWITCH RATING

AC DC

230V 10A 0.25A 125V 10A 0.5A

THERE ARE 2 FILTER IS GIVEN FIRST WATER IS FLOSHING TO TAKE WATER FROM RIVER THEN WATER IS

FED TO FILTER WHATEVER DUST PARTICLE IS IN WATER ALL JUST FILTERISED BY FILTER THEN WATER IS FED TO MOTOR. AFTER MOTOR IT SUPPIES WATER TO SECONDARY COOLING SYSTEM.

MOTOR FILTER FLOW METER

DRILL LINE

SECONDARY COOLING SYSTEM It is closed circulating system. The floor is located at an elevation of 180.25 m Due to the presence of large no of conductors and high currents flowing through

windings, a large amount of heat is generating. So cooling of generators is very important.

The secondary cooling floor generally involves the cooling of the generator. In TLDP-3 the generators are cooled by water in a closed pipe. This water is further cooled continuously at the primary cooling floor. From here the cold water is pumped to the various parts of the plant.

The secondary cooling floor employs the following components:

Two 3ph 415v AC motors

Heat exchanger

Differential pressure switch

Motors:

The motors used in the floor are simply used for pumping water in or out. One motor brings in the raw water and another motor pumps out the used raw water

SPECIFICATION OF SECONDARY COOLING MOTORS ARE:

NO OF PUMP MOTOR SET 8 RATING OF MOTOR 45KW(60HP) NO OF SIMPLEX STRAINER 4 NO OF CYCLONE SEPERATOR 1 NO OF HEAT EXCHANGER 5 VOLTAGE 415V CURRENT 80 A SPEED 1475 EFF 93% AMBIENT TEMPERATURE 50 C IP 55 CONNECTION DIAGRAM 302

HEAT EXCHANGER:

The heat exchanger is used for cooling the generator coolant using the raw water. Pressure and temperature meters are attached to the inlet and outlet pipes of the exchangers with measure the temperature and pressure of the inlet and outlet water.

THE SPECIFICATION OF AIR TO WATER HEAT EXCHANGERS:

HEAT LOAD 39KW VOLUME OF AIR CIRCULATED 1.7M3/S VOLUME OF WATER CIRCULATED 112 LPM WEIGHT 375KG

DIFFERENTILAL PRESSURE SWITCH:

The differential pressure switch is used check the functioning of the heat exchanger

It uses the pressure reading of the meters to determine whether the heat exchanger is working properly or not.

If the inlet and outlet pressures are different that means the heat exchanger is working properly and if there is no pressure difference it indicates some clogging within the heat exchanger. Then the exchanger is cleaned.

THE SPECIFICATION OF THE DIFFERNTIAL PRESSURE SWITCH IS:

ELECTRICAL RATING 15A , 250VA RANGE 0.4-4 KG/CM3 DEAD BAND 0.5KG/CM2 PROOF 140KG/CM2 MATERIAL TEFLON SV.PR. 33KG/CM2

TURBINE FLOOR THIS FLOOR IS LOCATED AT AN ELEVATION OF 184.5 M THE TURBINE EMPLOYED AT TLDP-3 IS KAPLAN TURBINE (VERTICAL

CONFIGURATION) The turbine floor includes the turbine, the runner blades and various other components. No of guide vane :- 24

Guide vane

Outer head cover

Regulating ring

Liver

Inner head cover

Over speed dripping device

Bearing

For Cooling

Additional Cooling

Cooling Pump

Hydraulic Leaking Device

Turbine Shaft

Lower guide bearing

Oil leakage Unit

The Kaplan Turbine is a propeller type water turbine which is adjustable blades. It is combined automatically adjusted propeller blades with automatically adjusted wicket gates to achieve efficiency over a wide range of flow and water level.

The Kaplan turbine was an evolution of the Francis turbine. Its invention allowed efficient power production in low head application that was not possible with Francis turbines.

The head ranges from 10-70 metre and the output from to 120 mw

Runner diameters are between 2 and 8 meters.

The range of the turbine is from 79 to 429 rpm.

SERVO MOTOR

OIL LEAKAGE UNIT

When servomotor start some leakage came out then oil is transferred to the oil leakage unit, then if the leakage unit is full then oil float switch sense give back to the OPU system.

BRAKING AND LIFTING PLANT:

Braking: - Air System

Lifting: - Rotor Lifting

This plant is associated with the braking of the alternator and also lifting the alternator with help of oil pressure.

The weight of our alternator is 350 tons, so it would be difficult to move such an alternator using water pressure. So the entire alternator along with the shaft is lifted so that the water through the gates could easily move the turbine which is connected with the alternator.

OIL AIR CAPACITY 1.5 LPM 1500 LPM WORK PRESSURE 240 BAR 7 BAR TEST PRESSURE 320 BAR 11 BAR

HIGH PRESSURE OIL PLANT

It is used for both AC and DC When the system is off then the runner, turbine settle down to the thresh bearing. When we have to start then oil is filled in the thresh bearing through a hole and then

slowly it lubricate and start the machine. If the pressure is not high then we can use DC thresh bearing. At a time only one is operated HPOS is used to create an oil film in between thrust pad and thrust collar Rotor is rotating on this oil film

CAPACITY 14.2 LPM WORKING PR. 300 BAR TEST PR. 350 BAR

OIL

AIR

OIL VAPOUR EXCITATION UNIT

CAPACITY 250 M3/Hr MAXIMUM OP. PR. 200 MM

HEAT EXCHANGER

A heat exchanger is a device that allows heat from a fluid (a liquid or a gas) to pass to a second fluid (another liquid or gas) without the two fluids having to mix together or come into direct contact.

For cooling purpose oil is used. First oil comes from generator which is hot so by using water pressure unit we cool the oil and exchange of that heat water goes out of the system.

PLATE PACK LENGTH 376 MM TEST PRESSURE 6 KG/M2 OPERATING PRESSURE 9 KG/M2 OPERATING TEMP. 90 C CAPACITY 394 LPM

Thresh Bearing for AC

Thresh Bearing for DC

M. VALVE

HP AND LP COMPRESSOR

Working pressure:-

HP compressor: - 62-64 Bar

LP compressor: - 7-8 Bar

COOLER

FILTER

Role of HP compressor: -

Provides air pressure to oil pressure unit(OPU) Air is provided to LP compressor from HP compressor

Role of LP compressor:-

Provides air for service Provides pressure to the maintenance seal. For braking pressure.

EXCITATION TRANSFORMER:

Excitation transformer is nothing but the source or minimum energy given to generator to generate voltage.

We know that the principle of generator is to convert mechanical energy into electrical energy. For this conversation it needs magnetic flux lines which get cut by generator coil and produce EMF. To produce this magnetic flux excitation transformer is used.

The secondary is rotating, which is connected to a rectifier bridge comprising of SCRs (thyristor) and freewheeling diodes which regulate the delivered current. In excitation with the brush, the whole arrangement is separate and the dc output is fed through brush to the rotor circuit for DC field

LP compressor

HP compressor

KVA 415 VOLT AT HV 11000 NO LOAD AT LV 225 CURRENT HV 21.7 CURRENTLV 1064.92 VECTOR GROUP Dy5 HIGHEST SYSTEM VOLTAGE 12KV MAX. AMBIENT TEMP. 50 DEG. MAX. TEMP. RISE 20 DEG IMPEDANCE VOLTAGE 5.44 CORE AND WINDING 1900 KG TOTAL WEIGHT 2500 KG

UNIT AUXILARY TRANSFORMERS (UAT):-

The unit auxiliary transformer is the power transformer that provide to the auxiliary equipment of a power generating station during its normal operation. This transformer is connected directly to the generator out-put by a tap-off of the isolated phase bus duct and thus becomes cheapest source of power to the generating station.

It is generally a three-winding transformer i.e. one primary and two separate secondary windings. Primary winding of UAT is equal to the main generator voltage rating. The secondary windings can have same or different voltages i.e. generally 11kv and or 6.9kv per plant layout.

KVA 500 VOLT AT HV 10000V NO LOAD AT LV 415V CURRENT HV 26.24 A CURRENT LV 695.6 VECTOR GROUP DYN11 MAX. AMBIENT TEMP. 50 DEG. MAX TEMP. RISE 90 DEG. IMPEDANCE VOLTAGE 3.95% CORE AND WINDING 1500 KG TOTAL WEIGTH 2250 KG

LAVT (LIGHTNING ARRESTER VOLTAGE TRANSFORMER):-

LAVT cubicles are enclosure for housing

1. Lightning arrester(LA)

2. Surge capacitor (SC)3. voltage transformer (VT)

1. To protect the generator from high voltage surge due to lightning stroke or electrical fault. LA & SC provide minimum resistance path to the short duration high voltage & high current because of lightning of fault and the complete current flows to ground earth point through the earthed bus bar

2. for measurement of voltage of a generating unit with the help of VT (a) For measurement of power (B) protection circuit (C) synchronization of the unit

VT of various accuracies step down the generator voltage of 6.6 KV to 15.7 KV to 110 Volt for the purpose of metering, protection and synchronizing purpose.

The design of LAVT cubicle depends on:-

1. voltage level of the generator2. Type of bus duct system between generator and step up transformer of the power plant.

NEUTRAL GROUNDING CUBICE (NGC): -

NGC is an enclosure for installation of neutral grounding transformer (NGT) and Neutral grounding Resistance (NGR) for grounding /earthing of neutral current during unbalanced three phase load of a generator. This is essentially required for protection of the generator.

The neutral grounding transformer (NGT) steps down the voltage of neutral bus from 6. KV/11KV/15.75 KV level to 110 volt or 220 volt level. this stepped down voltage is connected to a neutral grounding resistance and a ground earth terminal for bringing the voltage level ofneutral bus a close as possible to zero voltage level.

GENERATOR FLOORThis floor is located at an elevation of 187.25m. An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current.

Most alternators use a rotating magnetic field with a stationary armature but occasionally, a rotating armature is used with a stationary magnetic field, or a linear alternator is used.

In principle any AC electrical generator can be called an alternator, but usually the term refers to small rotating machines driven by automotive and other internal combustion engines. An alternator that uses a permanent magnet for its magnetic field is called a magneto.

From excitation it produces AC then it converts AC to DC then it fed to the rotor , the cooling water goes inside the rotor , rotor rotates then hot water goes out with outlet pressure

RTD: - Resistance temperature detector

DTTD:- Dial type thermometer detector

If we need to stop of generator for maintenance then first we have to give pressure for braking so if we get minimum speed then slowly we apply brakes and finally stop.

GENERATOR SPECIFICATION

INSULATION CLASS F TEMPERATURE RISE BP RATED SPEED 136.36 RPM RATED FREQUENCY 50 HZ PERMISSIBLE OVERSPEED 377 RPM MAX. AMBIENT AIR

TEMPERATURE 40 C

MAX. WATER COOLANT TEMPERATUER

30 C

TOTAL MASS 346000 KG DEGREE OF PROTECTION IP54 TYPE OF CONSTRUCTION IM8205(W8) CONNECTION STAR,2 FOLD PARALLEL DUTY TYPE S1 RATED OUTPUT 36670 KVA RATED VOLTAGE 11000+_10%V RATED CURRENT 1924.7 A RATED POWER FACTOR 0.9 RATED FIELD VOLTAGE 118

MACHINE HALLThis floor is located at an elevation of 190.5m. The machine hall consists of the OPU set, rectifiers, unit heads and simulation display screens.

OPU SET: -

It stands for oil pumping unit. The oil pumping unit set is used to pump oil to move the runner blades. The entire set consists of an accumulator and two motors. The oil is pumped through two big pipes which run from the unit head to the runner blades through the hollow shaft.

The main components of oil pressure system: -

Accumulator tank containing required volume of oil under compressed air. Oil pumping unit maintaining effective volume and pressure in accumulation tank. Controls of the oil pressure unit.

The oil pressure systems are rated from 4Mpa and 6.3Mpa pressure.

There are 4 oil pressure machine each having 33 MW power.

Guide vane: - Control the water pressure insert into the turbine.

Oil pressure is maintained to 60 kg/m2

Governor: - It varies the water flow through the turbine to control the speed or power output. Generating units sped and system frequency may be adjusted by the governer.

There is 1/3rd hydraulic oil and 2/3rd is air.

Used to control the runner blades and guide van.

The specification of OPU set:-

CHANGEOVER SWITCH 315A VOLTS 415V CURRENT 320A INCOMR -1 SUPPLY FROM UAB 2 320 A INCOMER-2 SUPPLY FROM UAB1 320 A OPU PUMP-1 110 KW OPU PUMP-2 110 KW OIL LEAKAGE PUMP GUIDE VANE 1.1 KW OFFLINE FILTRAION PLANT 75 KW

ACCUMULATOR TANK: -

An accumulator tank is a water chamber which has a pressurized internal air bladder. They are designed to be installed downstream of your pump and dampen water pressure spikes, reduce pump cycling, help increase the pumps life and battery power.

WHY WE USE FIELD BREAKER?

Field breaker is used to isolate / change the field excitation supply to the main excitation irrespective to the power plant.

It is also connected with discharge resistor for discharging the field winding while de-excitation of the generator set.

EXCITATION EQUIPMENT

Static 36.67 MVA/1KV/1924.6 A /50 HZ/0.9cos()

Rotor Voltage: - 118 v Current: - 899 A Resistance :- 0.133 75 C AVR type :- Thyne 5 Channel : - 2 Bridge :- 2 Configuration :- n:1 DC supply : - 220V AC supply :- 415 V

CONTROL ROOM The elevation of control room is 190.5 M The whole plant is controlled through SCADA (Supervisory Control And Data

Acquisition) In TLDP-3 there are two server namely server A & server B Control room has two more room, they like:-

1. Battery Room2. LTAC Room

TRANSFORMER GALLEYA Transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors the transformers coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformers core and thus a varying magnetic

field through these secondary winding. This varying magnetic field induces a varying electromagnetic force(EMF), in the secondary winding. This effect is inductive coupling.

o KVA (HV) 41000 KVA (LV) 41000 VOLT AT NO LOAD HV 220000 VOLT AT NO LOAD LV 11000 AMPERE HV 108 AMPERE LV 2152 NO OF PHASES 3 FREQUENCY 50HZ DIAGRAM DRG. NO. TK106832 TYPE OF COOLING OFAF IMPEDANCE VOLTAGE 12.14% CONNECTION SYMBOL YND11 MASS OF CORE AND WINDING 50000 KG MASS OF OIL 22500 KG TOTAL MASS 87000 KG MASS OF HEAVIEST PKG. 57500 KG UNTANKING MASS 50000 KG UNTANKING HEIGHT 7660 KG VOLUME OF OIL 25000 L AIR CIRCULATION 677 M3/MIN OIL CIRCULATYION 1000L/MIN MAXIMUM TEMP RISE OF OIL 50 C

TRANSFORMER OIL PUMP

HP 4.3 SIZE 100*100 DISCHARGE 1100 LPM. AMPS. 7 INSULATION CLASS F HEAD 11 RPM 2850 WINDING CONNECTION DELTA

Bucholz Relay: - It is for internal fault oil vaporises to gas then by force of gas it supply next

Centre tap changer: -If the voltage is coming less then we have to fix the voltage by 220v In main conservator Silica Gel is used RXCT: - Temp. Range : - 30-150 c

Bucholz Relay

Cable Box

Conservator

Cooler

Control Box

Centered Tap Changer

Cable

CONNECTION DIAGRAM

OFAF READING

Design pressure 35 kg/cm2 Test pressure 5 Heat Dissipation 200 kw Weight 1800 kg

SSTIt stands for station service transformer. These are fed through the incomers from external sources. These transformers are utilized in the absence of self generation.

GAS INSULATION SUBSTATIONA gas insulated substation is an electrical substation in which the major structures are contained in a sealed environment with sulphur hexafluoride gas as the insulating medium.

The main application for gas insulated substation today is:

High voltage installation (usually 115 kV and above although some manufactures offer equipment with voltage ratings down to 20 KV). The higher the voltage, the more favourable gas insulated technology becomes. The footprint of 764 KV conventional substations is enormous and GIS technology allows a significant size reduction.

Urban installation, usually but not always, GIS technology is used for installation in areas where the cost of real estate is a significant consideration.

Indoor installation: - It is generally not practical to build an air insulated substation inside a building, but GIS can easily go inside buildings.

In most cases, the circuit breakers in gas insulated substation employ SF6 as the interrupting medium as well as the insulating medium, but there is hybrid installation in which breakers use vacuum interruption. The gas pressure required for SF6 to serve as an interruption medium is much greater than the pressure required for it to be insulation medium.

Circuit Breaker

Isolators

Circuit Breaker

It is automatically operated electrical switch design to protect an electric circuit from damaged caused by over current or overload or short-circuit

Isolators

Isolators is manually operated mechanical switch that isolates the faulty section or repair from a healthy section in order to avoid occurrence of more severe fault.

Extension Valve

For increasing temp, the valve will short and for normal temp. valve will become normal.

Why we use GIS?

For cooling the bus bar Like if here generate 220 kV then at least 2m distance has to be done the effect will not

come. So the gap between the bus bar and pipe should be 180 mm If we don’t give sf6 gas then the system will burst out

Unit

Extension valve

3 Phases

VOLTAGE TRANSFORMER

Rated insulation level: - 245/460/1050 kV

HZ: - 50

Rated voltage factor: - 1, 9/30s

Total therm. Burden: - 1200 VA

Nominal/minimum pressure at 20 C = 0.65/0.58 Mpa

Mass: - 210 kg

CURRENT TRANSFORMER

Idyn: -125 KA

HZ: - 50

Insulation level: - 245/460/1050 KV

Ith =50/1 KA/s

Whatever machine is not working or supply to customers N2 gas is given so that the parts will not damage due to moisture in parts, we supply N2 gas before supply to the supplier.

In running condition, a metal name Aluminia is fitted inside so that Aluminia trap the moisture inside the running machines not give to the sf6 gas Captures and not mix with SF6 gas. If he moisture becomes high so that moisture have to taken out while maintenance.

In1 unit there are 3 earthing switch, 3 isolators, 3 High speed Earthing Switch

HIGH SPEED EARTHING SWITCH

Ur 235 KV Up 1050KV Lk/tk 50KA, 1S Pre 0.65 Mpa Er E1

ISOLATOR

Ur 245 Kv Up 1050 Kv Lr 400A Lk/tk 50KA, 1S Pre 0.65Mpa

EARTHING SWITCH

Ur 245Kv Up 1050Kv Lr/tk 50KA, 1S Pre 0.65 Mpa

CIRCUIT BREAKER

Ur 245 kV Up 1050 Kv Ir 4000 A Tk 1S Isc 50A Kpp 1.5 Il 125 A Pre 0.7 Mpa Uop 220 Kv Us AC 220Kv Us DC 240 Kv M 2100 kg m 51kg

TRANSMISSION

The power generated at generating station is in low voltage level as low voltage power generation has some economical values. Low voltage power generation is more economical than high voltage power generation. At low voltage level, both weight and wide of insulation is less in the alternator, this directly reduces the cost and side of alternator. But this low voltage level power cannot be transmitted directly to the consumer end as because this low voltage power transmission is not at all economical. Hence although low voltage power generation is economical but low voltage electrical power transmission is not economical. Electrical power is directly proportional to the product of electrical current and voltage of system. So for transmitting certain electrical power from one place to another, if the voltage of the power is increased then associated electric current of this power is reduced. Reduced current means less I2R loss in the system, less cross sectional area of the conductor means less capital involvement ad decreased current cause’s improvement in voltage regulation of the system and improved voltage regulation indicates quality power. Because of these three reasons electrical power mainly transmitted at high voltage level.

Lightning Arrester: -

Lightning Arrester

Wave trap

CVT (Capacitor Voltage Transformer)

Bushing

A lightning arrester is a device used on systems to protect the insulation and conductors of the system from the damaging effects of lightning. The typical lightning arrester has a high voltage terminal and a ground terminal. When a lightning surge(or switching surge, which is very similar) travels along the power line to the arrester, the current from the surge is diverted through the arrester, in most cases to earth.

Wave Trap: -

A wave trap (high frequency stopper) is a maintenance free parallel resonant circuit, mounted inline or high voltage AC transmission power lines to prevent the transmission of high frequency(40 KHz to 1000KHz) carrier signals of power line communication to unwanted destinations.

CVT (Capacitor Voltage Transformer): -

CVT is a transformer used in power systems to step down extra high voltage signals and provide a low voltage signal, for metering or operating a protective relay.

PROTECTION SCHEMEPROTECTION FAULT

Internal faults are those which occur within the circuit due so some special causes like short circuit, overheating, etc. to protect the circuit with these fault a typical circuitry of relay and metering devices is used. The various relays used here are:

Generator protection:

(1) Overvoltage type relays(2) Overall differential relay(3) Back impedance relay(4) Negative phase sequence relay(5) Loss of excitation(6) Pole slipping relay(7) Under voltage relay(8) Auxiliary relay(9) Earth fault relay

Line protection:

(1) Distance relay(2) Overvoltage relay(3) Definite earth fault relay(4) Carrier aided relay(5) Power swing protection(6) Auto enclosure relay(7) Over current relay

CONCLUSIONI would like to say that this training is an excellent opportunity for me.

The main objectives of this industrial training are to observe and practice how the basic machine knowledge and Engineering is applicable in the real industries.

It is not only to get technical experience but also to observe management practice and how to interact with fellow workers.