Kerala State Electricity Board

Idamalayar Hydro Electric Project

Situated in Eranakulam DistrictUnder Generation Circle,

Kothamangalam25km away from KothamangalamReservoir type of Dam at EnnakkalLive Storage Capacity of 1017.8 mcm

MWL, FRL, MDDL, Dead StorageMakes it the second largest reservoir

in Kerala(After Idukki which is of 1459.7mcm)

General Station Data

Erection Works of Power House started on 1981

 Trial Run conducted on 1987Plant commissioned on ????Power Generation and Irrigation

PurposesSituated in the Periyar Basin

General Station Data

COST Dam : 4450.00 Lakhs Tunnel : 545.00 Lakhs Surge Shaft : 147.00 Lakhs Penstock and Valves : 168.00 Lakhs Power House : 255.00 Lakhs Electrical Machineries & Works : 1367.50

Lakhs TOTAL : 8712.00 Lakhs

General Station Data

WORK STARTED ON : 1976 TRIAL RUN : JANUARY 1987

General Station Data

Has B, C, D, E, F & G types of QuartersAn Inspection BungalowA CanteenA Research & Dam Safety division of CivilConcrete Testing & Control LabA SchoolHostels for Girls’ n Boys’Post Office with (PIN 686 581)A grocery store near the canteenExplosive Storage (For rock blasting)(Now dysfunctional)

General Station Data

Has two checkpoints before colony Vadattupara routeChakkimedu route Checkpoint at Dam

General Station Data

Reservoir [Pondage] type of projectFrancis Type Turbine supplied by BHELTotal Installed Capacity of 37.5MW X 2 = 75MWSemi Umbrella type of Shaft Bearing ArrangementFully Static Exciter (Unit 1)Semi Static Exciter (Unit 2) [Due for replacement]No Black Start facility as of now, (DG Set under

Commissioning)No dead bus charging facility?Isochronous mode of operation is not supported

[issue of falling frequency]

Salient Features of the Project

Since this is a reservoir type of project, it acts as a base load station during summer months

Acts as a peaking station during monsoon timesHence stores water during monsoon while

other smaller projects are utilized to the max, without causing spill

In summer, drain during summer months by using up its water during summer for maximum rain water harvesting; while other smaller projects dry up.

Salient Features of the Project

General Schematic of the Project

DamLow Pressure Tunnel (Head Race Tunnel)Surge TankValve HousePenstocks (High Pressure pipes)Power House [Surface Powerhouse]Tail Race

[Apart from these Civil structures, the reservoir area [Fan type]is the primary component of any hydro electric power project]

Major Structures of the Project

Idamalayar Dam

Idamalayar Dam

Idamalayar Dam

Idamalayar Dam

Dam Details

Dam Details

LOCATION Latitude : 100 13’ 15” Longitude : 760 42’ 30”

HYDROLOGY Catchment Area : 380.79km2 + 101km2 of Nirar (TN)

Dam Details

DAM Type of Dam : Concrete Gravity Bed Level : 81.00m Deepest Foundation Level : 70.40m Height at Bed Level : 91.00m Length at Dam Top : 373.00m Top Width : 8.50m Bottom Width : 85.00m Volume of Concrete : 8.80 Lakhs m3

Dam Details

RESERVOIRFull Reservoir Level (FRL) : 169.00m Maximum Water Level (MWL) :

171.20m Minimum Draw Down Level (MDDL) :

115.00m Gross Storage at MWL : 1153.00Mm3 Gross Storage at FRL : 1089.80Mm3 Dead Storage : 72.00 Mm3 Water Spread Area at FRL : 2830.00

Hectares.

Dam Details

SPILLWAYCrest Level : 161.00m Width (4X15m) : 60.00m Max. Discharge : 4063.50 m3/sec

Dam Details

Crest Level & Width of Spill Way

Crest Level & Width of Spill Way

POWER INTAKE Size of Opening : 3100mm X

4746.73mm Size of intake : 4.20m dia.

Intake Details

For water discharge while the generators are not generating

2 No.s, 1500mm dia. Disperser Valves Maximum Discharge of 54.50

m3/sec/Each

Disperser Valve Details

HEAD RACE TUNNEL Shape, Type and Size : Circular,

Concrete, 5.20m dia. Length : 1564.00m Slope : 1/250 Max. Flow : 80m3/sec Velocity of Flow : 3177m/sec

Low Pressure Tunnel[Head Race Tunnel]

Low Pressure Tunnel Details

SURGE SHAFT Height : 89.116m Size : 21.70m dia. & 18.85m dia.

Surge Tank

Surge Tank Details

Valve House

Valve House Details

PENSTOCK VALVES 2 No.sButterfly Valves2.93m diameter

Valve House Details

Penstocks

HIGH PRESSURE PIPE Length : 114.40m Diameter : 4.20m

Penstocks Details

Power House

Power House Details

Tail Race

Tail Race Details

POWER EVACUATION

Two 110kV Feeders- IMMA (Idamalayar – Malayattoor) - IMCH (Idamalayar – Chalakkudy)

 One 66kV Feeder- 66kV IMKM Feeder

Acts as a Standby Supply and feeds the 11kV outgoing feeders normally

Salient Features

POWER EVACUATION from Idamalayar

SWITCH YARDSTwo Switch Yards

110kV Yard66kV Yard

Interconnected through a 110/66kV, Auto Transformer(Why Two winding/Single winding?)

Salient Features

Rated Head : 108.3m(Absolute value)

FRL : MSL +169.0mMDDL : MSL +115.0mTurbine CL : 39.00m?Tail Water Level: 39.00m?Suction Head:Net Head :

Salient Features

Control Room (MSL + 51.65m)

Service Bay (MSL + 48.00m) [Machine Floor]

Generator Floor (MSL + 44.00m) [Generator Barrel Floor]

Turbine Floor (MSL + 40.50m) 

Valve Gallery (MSL + 36.00m)

Power House

OperatorUnit PanelsUnit Alarm/Annunciation PanelsFeeder Panel IMMAFeeder Panel IMCH110/66kV Transformer Panel66kV IMKM Feeder Panel andAssociated Relay Panels

Control Room

Junior Operator & Shift AssistantAt a time, four operations staff in the Power

HouseHouses Turbine Generator PanelsExciter panelsAVR PanelsRegulation PanelsLAVT CubicleField Discharge Resistors (Field Ballast

Resistors)

Service Bay

Has OPU SystemsAir Oil TanksOPU PumpsGate Control PanelsGovernor [EHGC]PanelsUnit Auxiliary Transformers11kV Indoor PanelsOil Filtering UnitsStator CO2 Flooding SystemThrust Chamber Entry

Generator Floor

Main Oil ValvesESVsControl Panel of MIV and its Bypass

ValvesCooling Water SystemCooling Water Pumping SystemShaft Coupling Chamber Entry

Turbine Floor

Main Inlet Valves Oil Servos Single Acting with Counter Weight for Closing(Useful in case of Oil Drain) Draft Cone (Two Pieces) Draft Tube OpeningDraft tube with Circular Inlet & Rectangular Outlet. Increase in

net head by establishing a negative head at theturbine outletConverts a large proportion of ke rejected at the outlet into

pressure energyWithout a draft tube, the pressure at the outlet of the turbine

will be equal to the atm pressure.Draft tube increases efficiency

Valve Gallery

Cavitation in TurbinesCausesEffects

Valve Gallery

Stop Logs Level of Tail Race above Turbine CL Draft Tube Exits Double Exited Draft Tubes Tail Race Level Difference as goes

further downstream..

Tail Race

MIV

Equipment Details

Turbines

Equipment Details

Principle of reaction turbines

Generator Synchronous Alternator type 18 Salient poles Synchronous speed of

120X50/18=333.33rpm

Equipment Details

ExcitorRatingsLimitsCeiling Voltage

Equipment Details

ExcitorDC System at Idamalayar Power

Station A 220V dc system for the Units & 110kV

Feeders A 110V dc system for the 66kV

IMKM feeder A 48V dc system for the PLCC

systems A 24V dc system for the 11kV

OD CBs

DC System Details

Battery Types:- Plante type- VRLA typeRedundancy- 100% in Nuclear stations facilitaing

anytime testing of a bank without the operations from getting affected.

DC System Details

Charging- Float- BoostDrainage of charge (Formation of local cells)- Operations of the CBs- Relay CoilEnergization- Field Flashing- DC Motors for Gate Control- Indication Lamps- Emergency Lights

DC System Details

Unit Auxiliary Transformers

The name platedetails of the UATs

Maker: National Electrical Industries- 630kVA, 11000/433V, 53.1/840A - 3Ø - S/N: RY2692/1(UAT 1), RY2692/2(UAT 2),

RY2692/3(Standby)

Auxiliary Transformers

- Type of Cooling: SN, Frequency: 50Hz - Impedance: 4.86%, Vector Group: DYn11 - TapChanging: Off Load - Weight: Coreand Winding: 1270kg - Weight of Oil: 596kg, TotalWeight: 2578kg, Year: 1980, Tmax: 45°C

Auxiliary Transformers

Unit Auxiliary Transformers   The name platedetails of the UATs   - Maker: National Electrical Industries   - 630kVA, 11000/433V, 53.1/840A   - 3Ø   - S/N: RY2692/1(UAT 1), RY2692/2(UAT 2), RY2692/3(Standby) - Type of Cooling: SN, Frequency: 50Hz   - Impedance: 4.86%, Vector Group: DYn11   - TapChanging: Off Load   - Weight: Coreand Winding: 1270kg   - Weight of Oil: 596kg, TotalWeight:   2578kg, Year:1980, Tmax: 45°C

Auxiliary Systems in the Plant

LAVT Cubicle

Equipments

LA-SC Cubicle-Station Arrestor & Surge Capacitor

Equipments

Generator Breakers- Closing Time- Opening Time- Dead Time

Equipments

Generator Breakers- Closing Time- Opening Time- Dead Time

Equipments

Generator Breakers- Closing Time- Opening Time- Dead Time

Equipments

Generator CTs- Duct CTs- No of Cores and Spec.

Equipments

Generator PTs

Equipments

Generator PTs

Equipments

IMMA Line PTs

Equipments

IMMA Line CTs

Equipments

IMMA Line Breakers

Equipments

IMMA Line Breakers

Equipments

Lighting Arrestors for GTs    - LA Gradings- Insulation Coordination of Equipments at

a power station - Necessity

Equipments

Lighting Arrestors for GTs    - LA Gradings- Insulation Coordination of Equipments at

a power station - Necessity

Equipments

• Lightning Arrestors for IMMA

Equipments

Generator Isolators    - Isolators in General- Current Carrying Capacity

Equipments

Generator Isolators    - Isolators in General- Current Carrying Capacity

Equipments

• Line IsolatorsBus Coupler Isolator    - No CB herefor Coupling/ Decoupling operations- This results in generation loss that could ve been

avoided. Bus Coupler Isolator

Equipments

110/66kV Transformer

Equipments

110/66kV Transformer

Equipments

110/66kV Transformer

Equipments

Breakers for HT Side of 110kV Side

Equipments

Breakers for LT Side of 66kV Side

Equipments

• Bus PTs for 66kV Bus

Equipments

• Bus PTs for 11kV Bus

Equipments

Incomer 1 Transformer 66/11kVIncomer 2 Transformer 66/11kV

Equipments

Open fuses on the HT side of the Incomers

Equipments

Dam/Colony and Chakkimedu 11kV Feeders

Equipments

Dam/Colony and Chakkimedu 11kV Feeders

Equipments

EOT Crane in Service Bay    Earth Mat in the Yard

Equipments

EOT Crane in Main StoreEOT Crane in Valve House

Equipments

Protections:   - Of the Machine   - Of the Feeders   - Of the Transformers   - Start/Stop Sequence   - Relays for the Start/Stop sequencing   -       Fire Protection Systems   - CO2 Flooding System for Generator Stator   - Water Deluge system for the GTs   - CO2 portable cylinders   - AFFF portable cylinders   - DCP portable cylinders

Protection Systems

Cooling Systems in place:   - Oil HeatExchangers at UGB, LGB,TB and TGB   - Surface Air Coolers for the Generator Stator   - UsesPenstock bleeding than the pumping method since the reservoir is large

and the headis small, which results in an affordable loss comparedto thepumping method.

Lubrication:   CGLU units- serves lubrication needs of the Servomotors, Guide vane

bushings etc. Ejector Pump:   Works with the Ventury principle, clears the water leakage from the   TGB's shaftseal side   Shaft Sealing:   Why not Pelton for medium and high heads?

Cooling Systems

Oil Filtering Units   OPUs   OPU pumps - redundancy   AOT   HP/LP Air Compressor Systems - Redundancy   Drainage Pit Leakage Water Pump Leakage Oil Pump Leakage Oil Collector under bearings   Pumps for removing the leakage oil fromthese collectors   Measurement / Instrumentation System:   - Condition Monitoring   - RTDs/TSDs for temp measurement   - Rotor temp measurement   -   - Permit to Work on Machines/Feeders/Other Equipments   - AVR   - Thyristor Panels - Redundancy   - Regulation Cubicle   -

CBs Operation SF6 Air Blast   Vacuum   Air   Spirng/Air for Close / Open   Thrust bearing - Russian design - Pin type Thrust Beaing pads   (Kingsbury Pins)   SemiUmbrella advantage - Minimization of Iron cost   Mattress type pads   HPOP system   Jacking Up of Rotor - Necessity   - Min Continous OperatingSpeed   Braking   Brake Pads - position below rotor, lifts the rotorup while stopping Saves the babbitting from getting damaged due to the increased friction during the slow speeds

Power Transformer & DistributionTransformer

 Tests Meggering PIIR PDCT Secondary Open situation - no

issuefor a while Capacitor Banks - Functions Turbine Mode/Condenser mode

StartupNormalSpin GeneratorGeneratorSpinning Reserve?

Start Up & Shutdown

ShutdownModes:   Controlled Action Shutdown   - Initiated under non urgent mechanical/electrical faults of turbine   & generator   - Once this signal is received, governer stop is initiated which results in the

closing of the guide vanes/jetsto the no load values - GCB is opened (Nothing is mentioned abt Excitationcontrol) IfGuide vanes dont

close/GCB and FB dont trip in preset time, Controlled Action Shutdownis consideredfailed. Goesto Emergency SHutdown

- Initiated when the controlled action shutdown fails   - Initiated usually under electrical & mechanical faults listed happen - Operates the Emergency Closing Valve & GCB simultaneously   - Guidevanes/Jets are closed very fast   - FB tripping is doneonce the GCB is opened.   - If Guide vanes dont close/GCB and FB dont trip in preset time, Catastrophic

Shutdownis initiated

Start Up & Shutdown

Catastrophic Shutdown - Initiated when a catastrophic

condition arises - Or Controlled Action/

Emergency SHutdown programfails

 - Commands given to

simulataneously close MIV, toOpen Emergency

 Closing Valve, Trip GCB and FB

finally     Catastrophic Shutdownis same as

Emergency shutdown exceptMIV closing command is givensimultaneouslyas the EmergencySolenoid valve is opened in theFormer case.

Capability Curve FGMO RFGMOGoverner Auto Governer Manual

Synchronizing