Descriptive Manual for Power Station

Owner

MAGMA NUSANTARA LTD

Project
WAYANG WINDU UNIT 2
GEOTHERMAL POWER PROJECT
Contract No. Contractor

71510012-OS Sumitomo Corporation

MNL Drawing No. Revision

WW2-GN-PS-0110 1
Dwg. Status

AS BUILT
O/S No. B10159
Internal Dist.
Revision Drawn Checked Approved Date
Copy to
PM 1 A. Issued as built N. Y. N. Y. H. M. 10 Feb. '09
[火プ設] 0 B. Some descriptions are added
according to MNL request
N. Y. N. Y. H. M. 24 Mar. '09
[火プ建]工事 0
[火プ建]電工 0
(火建試) 0
Drawn N. Yamaguchi 31 Oct '08
(火電制)電気 0
(火電制)制御 0
Checked N. Yamaguchi 31 Oct '08
(火プ品) 0
(火技工) 0
Approved H. Murakami 31 Oct '08
(火計設) 0
(火構設)K 0
(火構設)P 0
(火構設)R 0
Drawing No.
(火構設)H 0 B10159-DKT/D962
(回構設) 0 B
(回開設) 0 A
Wayang Windu 2
(O/S No. B10159) Descriptive Manual

Wayang Windu Unit 2 Geothermal Power Project

Descriptive Manual for Power Station

1. PROCESS OVERVIEW
The separated main steam containing some non-condensable gases is supplied from two 36” steam lines to a
48” header after any liquid droplets are removed from the steam through the steam scrubbers. The design
steam supply conditions are 10.9 bar absolute at 184°C and flow of approx. 220 kg/s.
The turbo generator is supplied from the steam header via a 44” line through steam strainers, steam turbine
main stop valves and steam flow control valves. To control the output of the turbo generator, the turbine gov-
ernor operates the steam flow control valves.
The FES 117 MW steam turbine is directly coupled to the FES two-pole 137.5 MVA 13.8 kV generator. The
steam turbine is a single casing, double-flow, reaction type with eight stages in each flow. The generator is
three phase 50Hz air cooled with forced air cooling using water.
The generator electrical output is supplied to the PLN grid via a generator transformer that increases the volt-
age to 150kV. An additional connection to the generator output is used to supply the power station electrical
plant through a 13.8 kV to 6.3 kV unit transformer. A circuit breaker with disconnecting / earthing switches is
installed between the generator and transformer. The generator can be synchronized to the PLN grid using
this circuit breaker.
After doing work in the turbine the steam is exhausted to a direct contact spray type condenser mounted be-
neath the turbine. Cooling water delivered from the cooling tower through the condenser spray nozzles is
used to condense the steam through direct contact.
The condenser cooling water and condensed turbine exhaust steam collects in the condenser hotwell as con-
densate. Two 50% duty hotwell pumps remove condensate from the hotwell and deliver it to the cooling
tower.
In the cooling tower heat is removed from the condensate by the air flowing through the cooling tower. The
cooling tower is a counter flow type forced draught type with motor driven fans to provide the forced draught.
The loss of cooling water that is carried away in the water vapour plume of the cooling tower is not enough to
counter the additional condensed steam. A cooling tower level control system is used to remove excess con-
densate to the SAGS condensate re-injection system.
Non condensable gases are collected and removed from the condenser by the gas removal system. The gas
removal system is a hybrid system using steam ejectors and liquid ring vacuum pumps to remove non-
condensable gases and deliver them to the cooling tower. The steam supply to gas removal system is by a 10”
supply line branched from the main steam pipe to the turbo generator. The non-condensable gases are dis-
charged to the cooling tower above the fans and are carried away in the thermal plume of the cooling tower.
An auxiliary cooling water system supplied from the cooling tower basin outlet pipe is used for cooling tur-
bine lube oil, generator air coolers and the gas removal system inter and after condensers. Two 100% duty
auxiliary cooling water pumps are installed for circulation of the auxiliary cooling water.
The plant compressed air system, a common system for Unit 1 and 2, uses three rotary screw compressors
with two existing air receivers and one new receiver that supply the instrument air and utility air. Instrument
air is supplied via heat-less air dryers and filters to control valves and other instruments that require clean dry

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air. Utility air is supplied via an auto shut off valve that will close if instrument air pressure falls.
Plant fire protection system includes automatic and manual sprinklers, fire hydrants and portable fire extin-
guishers. Fire detection is by heat sensors and smoke sensors. Diesel and electric fire pumps are installed to
supply water to the sprinkle and hydrant systems.
Plant electrical systems use 6.3 kV supplies for major auxiliary plant equipment and 6.3kV / 380 V trans-
formers to supply general auxiliary equipment. An 1100 kW emergency generator supplies the 380 V systems.
125V and 230V DC systems use batteries and battery chargers for essential supplies. Essential no-break AC
equipment such as the DCS is supplied by UPS that use rectifiers, batteries and inverters.
The plant is controlled from a central control room adjacent to the turbine house. A distributed control system
is used for all start, stop, and on line operations and monitoring. Automatic turbine start, synchronizing, load-
ing, shut down are achieved by used of the plant control systems. Automatic control of critical and important
process conditions is included in the distributed control system functions. Remote switching of electrical
equipment and automated sequential starting and stopping of major auxiliaries is another feature available to
the operators in the control room.

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2. STEAM SUPPLY SYSTEM

2.1 System Design

The Wayang Windu Unit 2 geothermal power plant has a main steam header that allows for steam inlet from
the two scrubbers, and steam supply to the turbo generator and gas removal system. The design steam sup-
ply conditions are 10.9 bar absolute at 184°C and flow of approx. 220 kg/s.
FES recommendation for the steam quality for the turbine is provided by "Operation and Maintenance Man-
ual for Turbine, Condenser and Generator" (WW2-ME-TG-5610).
The scrubbers are connected to the steam header by 36” lines with manually operated isolating valves.
The turbo generator is supplied from the steam header via a 44” line, this is fitted with a 48” motorized iso-
lating valve and a manually operated bypass valve at the header connection. A steam flow meter device is
fitted in the 44” line. The turbo generator steam supply line divides into two 32” lines inside the turbine
house. The division to two lines is made to provide for steam admission to each side of the turbine. Each 32”
line is fitted with a steam strainer before admitting steam to the turbine stop valves.
The gas removal system is supplied via a 10” line branched from the 44” line at the downstream of the
steam flow meter, which is called as auxiliary steam supply line. This 10” line is fitted with a 10” motorized
isolating valve and manually operated bypass valve. A steam flow meter device is fitted in the 10inch line.
The turbo generator supply and gas removal system supply isolating valves can be remotely operated from
the control room using the DCS.
Drain pots and steam traps are fitted to the main steam header, the turbo generator supply line and the auxil-
iary steam supply line. There are nine traps in total with them fitted on the header, at the header take connec-
tions, upstream the flow meter devices and at the inlet of each gas removal train. The steam traps are all fit-
ted with bypass valves. The steam header trap and steam line traps closest to the header are discharged to
SAGS drain system. The steam flow meter upstream traps and gas removal system inlet traps drain to the
plant steam drain chamber.
A flow meter of Venturi type is fitted in the 44” main steam line and an Annubar type meter is fitted in the
10” auxiliary steam supply line. The flow meters provide inputs to the DCS to give remote indication and
logging of the steam flows.
Instrumentation field equipment is fitted to provide main steam header pressure, turbo generator supply
pressure & temperature and auxiliary steam pressure & temperature inputs to the DCS.

2.2 Equipment Design Data

2.2.1 Unit 2 Main Steam Supply Stop Valve
Equipment number 0-MSV-102, 0-MSV-103
Manufacturer Samwoo KJS Tech
Type Wedge gate valve
Size 36 inch
Material ASTM A216-WCB (body and disc)
Operation Manual

2.2.2 Main Steam Supply Stop Valve

Equipment number 2-MSV-100
Manufacturer Toyo Valve
Type Wedge gate valve
Size 48 inch

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Material ASTM A216-WCB (body and disc)

Operation Motorized

2.2.3 Auxiliary Steam Supply Stop Valve

Equipment number 2-ASV-100
Manufacturer Samwoo KJS Tech
Type Wedge gate valve
Size 10 inch
Material ASTM A216-WCB (body and disc)
Operation Motorized

2.2.4 Main Steam Flow Meter (Venturi)

Equipment number A2-FE-0106 / A2-FIT-0106
Manufacturer KSC Corporation / Rosemount
Model 44” CL150 / 2088G3S33A1B4M5Q4
Material SUS316L (throat) / Hastelloy C-276 (diaphragm material)
Pipe size 44 inch
Flow range 0 ~ 250 kg/s
Normal flow 219.64 kg/s
Flow co-efficient, K value 0.985

2.2.5 Gas Removal System Inlet Steam Flow Meter (Annubar)

Equipment number A2-FIT-0205
Manufacturer Rosemount
Model 3095MFAS100CSHGH2A3N6032BA1AQ8Q4M5T1
Material Hastelloy C-276 (Sensor material)
Pipe size 10 inch
Flow range 0 ~ 10 kg/s
Normal flow 6.3 kg/s

2.2.6 Steam Strainer

Equipment number STR-201, STR-202
Manufacturer Fuji Electric Systems
Type Bucket
Size 32 inch

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3. TURBINE SYSTEM

3.1 System Design

3.1.1 General
The 117 MW FES manufactured and supplied steam turbine is a single cylinder, double flow, dual en-
try, condensing type. The condenser is a direct contact type mounted beneath the turbine and is di-
rectly connected to it. The turbine is direct coupled to the two-pole generator and runs at 3000rpm.
Normal steam conditions at the steam strainer inlet flange is 10.7 bar absolute at 183°C with a con-
densing exhaust pressure of 0.11 bar absolute.
The 44” steam supply line from the header divides into two 32” lines to supply each side of the tur-
bine through the bucket type filters. The steam supply to the turbine is opened and closed by, swing
check type, main stop valves that are held open by hydraulic actuators when the turbine is operating.
The turbine steam supply on each side divides after the main stop valves and two governor controlled
steam flow control valves are fitted to each side of the turbine. The four 24” butterfly type steam flow
control valves modulate under governor action to control the steam flow and subsequent turbo genera-
tor output.
See section 4 for a detailed description of the turbine controls.

3.1.2 Turbine Casing

The turbine casing is fabricated from steel plate welded with single casing and split with a horizontal
joint flange. The two steam inlets are in the bottom section just below the horizontal half joint. The
stationary blades for the first five rows are calked into “L” shaped grooves in the one internal casing.
The last three blade rows have the blades welded to a stationary blade ring that is bolted to the casing.
There are two condenser connections at the bottom of the turbine casing at each exhaust end. Bellows
type flexible joints are used to allow for differential expansion between casing and the condenser that
is solidly mounted on the turbine basement floor.
Two bursting disk type, pressure relief fittings are mounted on the top of top section of the turbine
casing to ensure the turbine and condenser cannot be pressurized.
See section 5 for a detailed description of the condenser and cooling water system.

3.1.3 Turbine Blading

There are 8 stages of reaction blades in each of the dual flows. The first six stage blades are manufac-
tured with integral shrouds. This is done because the blades are stronger and not affected by vibrations
in the normal operating speed range.
The final two stages moving blades are free standing, they are twisted along their length with no
shrouding or lacing wires used for support.
The first six row moving and stationary blade shrouds are fitted with labyrinth seals calked into the
shrouds to reduce blade tip leakage. The final two stages stationary blade diaphragms are fitted with
labyrinth seals to reduce steam leakage at the blade tips. Stellite erosion shields are welded on to the
leading edges of the last two rows of moving blades to reduce erosion due to impact with water drop-
lets.
Each stationary blade ring has a circumferential drain catcher arrangement to allow water droplets
thrown out radially by centrifugal force to escape to the condenser and bypass the next row of blades.
A turbine blade washing system is installed to enable blade washing to be done on load to remove any
silica deposits that may build up on the blades. Two ten stage centrifugal pumps are used to pump wa-
ter from the cooling tower basin through a system of distributor nozzles in the turbine steam inlet belt.

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3.1.4 Turbine Rotor

The turbine rotor is made from a solid forging. The first six rows of blades are fixed in to T slots ma-
chined in the rotor. The last two rows of blades are fixed using “fir tree” roots in slots machined axi-
ally into the rotor.
The turbine rotor has two journal bearings fitted in spherical mountings and a tilting pad type thrust
bearing at the outboard end. The bearing lube oil is supplied via dual 100% duty oil coolers and filters.
A high-pressure oil supply to each journal bearing from the jacking oil pump is used on start up to lift
the shaft and allow the turning gear to be effective rotating the shaft.
See section 4 for detail on the oil systems
The outboard end of the rotor shaft is fitted with centrifugal operated over-speed protection. A shaft
driven oil pump is coupled to the outboard end of the turbine rotor. The main oil pump shaft is fitted
with a toothed wheel for the turbine speed detection device used for a governor control input.

3.1.5 Glands
The two turbine glands are of the labyrinth type, they are supplied with steam from the control room
side, main steam supply before the turbine main stop valve. The gland system has a leak off connec-
tion to the gas removal system via a fixed regulating orifice. The gas removal system maintains a
slight vacuum on the leak off chamber of each gland. Gland steam leakage in to the chamber and air
leakage into the chamber are removed by the gas removal system and discharged to the cooling tower.

3.2 Equipment Design Data

Note see section 4 for details of controls indications and operational limits.

3.2.1 Turbine Main Stop Valves

Equipment number 2-MSV-101A, 2-MSV-101B
Quantity Two per unit
Manufacturer Fuji Electric Systems
Size 800 mm
Type Swing check

3.2.2 Turbine Governor Valves

Equipment number 2-MSV-102A, 2-MSV-102B, 2-MSV-102C, 2-MSV-102D
Quantity Four per unit
Manufacturer Fuji Electric Systems
Size 600 mm
Type Butterfly

3.2.3 Steam turbine

Equipment number ST-200
Manufacturer Fuji Electric Systems
Type Single casing, dual flow, dual exhaust, condensing
Number of blading stages Eight
Rated gross output 117,000 kW
Rated steam pressure 10.7 bar absolute
Rated steam temperature 183 °C
Back pressure at exhaust 110 mbar absolute
Turbine pressure relief device
Operating pressure 0.5bar gauge
Direction of rotation Clockwise viewed from the generator side
Critical speeds

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Turbine rotor 1950 rpm

Turbine free standing blades 2750 and 3230 rpm

3.2.4 Hydraulic Turning Gear

Equipment number HTG-200
Type Hydraulic
Speed of rotor 80 – 120 rpm

3.3 Performance and Operation Limit

- De-rating curve of net steam rate ATTACHMENT-1
- Gross output vs turbine inlet pressure ATTACHMENT-2
- Off-frequency operating limits Allowable speed for continuous operation: 2850 - 3150 rpm
(Operation with speed < 2850 rpm or > 3150 rpm in only allowed for 120 minutes cumulatively through-
out the turbine life time.)

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4. TURBINE LUBRICATING AND CONTROL OIL SYSTEM

The turbine oil system provides oil to the turbine systems for
¾ Lubrication and cooling of the turbine bearings
¾ Hydraulic turning-gear drive
¾ Jack up of turbine and generator rotor at start up and shutdown of the turbine
¾ Control oil for operating signals of the turbine tripping and some protective devices
¾ Servo motor for the position control of main stop valves, governor valves and protective devices

4.1 System Design

4.1.1 Mail Oil Pump
For on load operation the shaft driven single stage double entry centrifugal main oil pump provides all
the control oil and lubricating requirements.
Š The control oil is supplied from the main oil pump discharge.
Š The servo motor oil is supplied from the main oil pump discharge.
Š The lubricating oil is supplied from the main oil pump discharge via the filters and coolers.

4.1.2 Main Oil Tank

The main oil tank provides the functions of oil system reservoir and supply. It is the collection point
for return oil from the oil systems.
Return lubricating oil and control oil enter the tank via coarse filter baskets to remove solid debris.
The oil tank has internal baffles to ensure the oil is held in the tank for a time period to allow release
of any entrained air and suspended particles.
An injector mounted in the main oil tank is used on the main oil pump suction to lift the oil from the
tank to the main oil pump suction. The injector is supplied with operating oil from the main oil pump
discharge. There is a foot valve in the injector inlet to prevent back flow through the injector when the
auxiliary oil pump is running.
The auxiliary and emergency oil pumps are mounted on top of the tank. The jacking oil pump can be
supplied from the bottom of the tank. The oil tank is fitted with a vapour extraction fan that maintains
a slight vacuum on the tank and bearing oil return lines.
The main oil tank is fitted with electric heating elements that maintain the tank temperature between
35°C and 37°C when the turbine has been off load and the lube oil has cooled.

4.1.3 Auxiliary Oil Pump

The auxiliary oil pump is a vertical mounted single suction centrifugal type pump. The pump is fitted
to provide oil supplies when the turbine is stopped, being started and shutting down.
The auxiliary oil pump discharges into the main oil pump discharge line, and supplies lubricating oil
and control oil systems and the hydraulic turning gear. A foot valve in the main oil pump injector’s
inlet prevents a back flow through the pump when the auxiliary oil pump is running.
The auxiliary oil pump is started and stopped automatically when pressure changes are detected at the
main oil pump and auxiliary oil pump discharge.

4.1.4 Emergency Oil Pump

An emergency DC powered lubricating oil pump is fitted. This pump is vertical mounted single entry
centrifugal type. The pump supplies oil direct to the turbine bearings, bypassing the filters and coolers.
The emergency oil pump does not supply anything else.
The emergency oil pump starts automatically on detection of low bearing oil pressure.

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4.1.5 Jacking Oil Pump

A positive displacement high-pressure oil pump supplies oil to the turbine and generator journal bear-
ings. The high-pressure oil lifts (jacks) the turbine and generator shafts off the bearings and allows the
turning gear to move the shaft. The jacking oil pump is a 7-cylinder swash plate reciprocating type
pump.
This pump is used when first starting the turning gear and at all times when the turbine is turning by
use of the turning gear. Operation of the pump is automatic with starting and stopping being initiated
by the turning gear start and stop.
The jacking oil pump can be supplied from the main oil tank or the bearing lubricating oil supply line
after the filters. There is non-return valve in the oil tank supply to prevent backflow of lubricating oil
to the tank when the jacking oil pump is shut down.

4.1.6 Hydraulic Turning Gear

The hydraulic turning gear is a small oil turbine that is fitted at the turbine inboard bearing on the tur-
bine coupling. The turning gear is supplied with oil from the auxiliary oil pump via the main oil
pump’s discharge line.
A remote operated solenoid valve is used to control the oil supply to the turning gear. The solenoid
valve is operated via the DCS it is set to automatically open on turbine run down before the shaft
stops, and to close on a turbine speed increase above 250 rpm.
The turning gear oil returns to the main oil tank via the bearing oil return line.
A manual operating lever can be applied to the turning gear to turn the shaft in emergency if required.
The shaft is turned at 80 – 150 rpm by the turning gear.

4.1.7 Oil Coolers and Filters

The two 100% duty oil coolers are cooled by water supplied from the auxiliary cooling water system.
The oil temperature is regulated by the action of the cooling water flow control valve fitted to the wa-
ter supply line. There is local and remote indications of the lubricating oil temperature and pressure.
The two 100% duty bucket type oil filters are fitted with a transfer valve for changing over the duty
filter. The transfer valve ensures that the correct valve operation occurs during filter change over. The
oil filters should be changed over and the fouled filter cleaned when the differential pressure exceeds
0.5 bar. There is only local indication of filter differential pressure.
The lubricating oil flow to each bearing can be regulated by action of the throttle valve fitted in each
bearing oil supply pipe.

4.1.8 Oil Purifier

A coalescing oil purifier mounted on the power house ground floor is gravity fed from the main oil
tank and discharges to the air vent line above the oil level in the tank. The oil purifier is operated lo-
cally.

4.1.9 Lube Oil Storage Tank

A lubricating oil storage system is provide to allow the
Š The turbine lubricating oil tank to be emptied for inspection and or maintenance.
Š The turbine lubricating oil to be treated outside of the turbine oil tank.
The system is common with the Unit 1.

4.2 Control, Alarm and Indications

4.2.1 Main Oil Tank
Local indications of the tank level and temperature are provided.
Remote DCS high level alarm is initiated at +50mm and low level alarm at –100mm, the alarms are
provided from a float mounting separate to the indication equipment.
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4.2.2 Auxiliary Oil Pump

Local indication of the oil pressure is provided.
Remote DCS indications (Auto Start, Trip, Manual or DCS position) are provided.
Cut in pressures control oil is under 5.0 bar g.
Cut out pressures control oil is above 8.0 bar g.

4.2.3 Hydraulic Turning Gear

Cut in speed is under 200 rpm.
Cut out speed is above 300 rpm.

4.2.4 Oil Coolers and Filters

Local indications of the cooler inlet/outlet temperature and filter differential pressure are provided.
Remote DCS indications of the cooler outlet temperature and the lubricating oil supply pressure at the
oil filter outlet are provided.

4.2.5 Oil Purifier

Local indications of the supply oil pressure, the heated oil temperature and the coalescer pressure are
provided.

4.3 Equipment Design Data

4.3.1 Main Oil Tank
Equipment number T-200
Manufacture Fuji Electric Systems
Capacity 12.5 m3 normal
Lube oil Turbine oil ISO VG-32

4.3.2 Oil Injector

Equipment number OE-200
Manufacturer Fuji Electric Systems
Model JP12B/28

4.3.3 Oil Tank Vapour Extractor

Equipment number VE-200
Manufacturer Izumi Sofuki
Capacity 5.5 m3/min
Motor horsepower 0.75 kW

4.3.4 Main Oil Pump

Equipment number P-201
Quantity One
Manufacturer Fuji Electric Systems
Model MP-500/8-1
Capacity 500 m3/hr @ 8 bar gauge

4.3.5 Auxiliary Oil Pump

Equipment number P-202
Manufacturer Kansui Pump
Model 150 VSC-1 #3090
Capacity 191 m3/hr @ 6.8 bar gauge

4.3.6 Emergency Oil Pump

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Equipment number P-203

Manufacturer Kansui Pump
Model 65 VSC-1 #2640
Capacity 25 m3/hr @ 1.9 bar gauge

4.3.7 Jacking Oil Pump

Equipment number P-204
Manufacturer Bosch Rexroth
Model A10VO100DR/31R-PPC12N00M
Capacity 4.80 m3/hr @ 140 bar gauge

4.3.8 Lube Oil Cooler

Equipment number E-211, E-212
Quantity 2 per unit
Manufacturer Yamashina Seiki
Model 2LCV-70B20T16P20
Quantity of cooling water 180 m3/hr @ 30°C
Quantity of lube oil 48.8 m3/hr
Oil temperature at cooler inlet 70°C
Oil temperature at cooler outlet 45°C
Design pressures 10.3 bar gauge (shell side) / 4.0 bar gauge (tube side)
Hydro test pressures 15.5 bar gauge (shell side) / 6.0 bar gauge (tube side)

4.3.9 Oil Filter

Equipment number FLT-200A, FLT-200B
Quantity 2 per unit
Manufacturer Taisei Kogyo
Model T-COS-L-24-A-200W-T
Material of element Stainless steel & electro galvanized steel
Design temp pressure 77°C, 10 bar gauge
Max allowable working pressure 4.5 bar gauge
Test pressure 15 bar gauge

4.3.10 Oil Purifier

Equipment number OP-200
Manufacturer Toyo Oil Machinery
Model TLC-2000H
Capacity 2000 l/hr
Fluid Turbine oil ISO VG-32
Temperatures min. 4°C - max. 77°C
Motor 1.5 kW
Type Coalescer

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5. GENERATOR AND MAIN ELECTRICAL CIRCUIT

5.1 System Design

5.1.1 Generator
The 137,500kVA FES manufactured and supplied generator is a two-pole, air-cooled machine fitted
with brushless excitation, generator neutral grounding cubicle NGC-200, generator voltage transform-
ers GVT-200, VT/SA-200 and digital automatic voltage regulator AVR-200. The stator winding insu-
lation is F class, using mica tape impregnated with epoxy resin. The stator winding temperature rise is
B class. The generator rotor is made from a single forging.

5.1.2 Generator Cooling

Air is circulated inside the generator, the exciter casing rotating rectifier casing and coolers by axial
flow fans that are fitted to each end of the generator rotor.
Air coolers mounted on the side of the generator are cooled with water from the auxiliary cooling wa-
ter system. A collection point and water detector is fitted under the air coolers at the turbine end of the
generator. In event of a cooler tube leak an alarm will be raised to alert the operator.
Four coolers and four internal air paths are used, two internal circulating air filters are fitted in the
cooler air flow paths. Make up air is drawn through two filters into the suction side of the fans at each
end of the generator.
Circulated and make up air filters are a catalytic type that use activated manganese dioxide to remove
sulphurous acid gas, hydrogen sulphide, chlorine and phosgene. The filters are expected to remove
95% of the gases, and last for one year between changes.

5.1.3 Excitation and Automatic Voltage Regulator (AVR)

The generator uses a brushless excitation system. The 3 phase AC exciter output is produced on the
rotor, and connected to a set of rotating silicon rectifiers also mounted on the generator rotor. The DC
output of the rotating rectifiers is applied to the rotor windings to produce a magnetic field.
The output voltage of the generator and generated power factor is controlled by the AVR, which regu-
lates the field current of the exciter. A shaft driven permanent magnet generator output is applied to
the AVR where it is rectified using silicon thyristors to rectify and regulate the DC field current for
the exciter.
The AVR is a redundant digital controlled system.
Operating features of the AVR are
Š Bump-less transfer to auto and to manual.
Š Selectable to VAR and voltage control modes.
Š Frequency droop response to lower the AVR voltage set point at low operating frequency to pro-
tect the generator transformer.
Š Variable, load related, under and over excitation limiting.

5.1.4 Generator Circuit Breaker

The generator circuit breaker with disconnecting switch & earthing switch is located between the gen-
erator and the generator transformer.
The generator circuit breaker is an SF6 type with a hydraulic stored spring energy operating mecha-
nism. The circuit breaker can be operated from the Auto-synchronizing panel at the control room for
automatic and manual synchronizing. From the DCS operator workstation the circuit breaker can only
be opened.
The disconnecting switch & earthing switch are contained inside the generator circuit breaker. The
switches have motor drive operations, it can only be operated locally and is controlled by an interlock

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key system.

5.1.5 VT/SA, GVT Cubicles

The VT/SA cubicle is installed to provide surge protection by the arrestors and capacitors, and also its
voltage transformers provide electrical protection and supervising of the 13.8kV main circuit.
The GVT cubicle also provides for electrical protection and supervising of the 13.8kV main circuit by
its voltage transformers.

5.1.6 Isolated Phase Busduct

The generator output is transmitted to the generator transformer through the isolated phase bus duct
(IPB). The generator circuit breaker with disconnecting switch and earthing switch is connected to the
IPB.
Also connected through the generator IPB are the unit transformer and the VT/SA & GVT cubicles.
The IPB conductor and outer shield is aluminum, the insulation medium is provided by dry air sup-
plied from the instrument air system through a cartridge type air dryer.

5.2 Equipment Data

5.2.1 Generator
Equipment number TG-200
Manufacturer Fiji Electric Systems
Type FTLRI544/63-2
Output (continuous) 137.5 MVA
Terminal voltage 13,800 Volts
Line current 5753 Amperes
Insulation class F (Stator & Rotor)
Power factor 0.85 lagging
Frequency /no of phases 50 Hz / 3 phase
Rotating speed 3000 rpm
Excitation method Brushless
Number of poles Two
Generator Type FTLRI
Rotor Critical Speed
Below synchronous speed 1,200 rpm (Generator shaft)
1,230 rpm (Combined unit)
Above synchronous speed 3,180 rpm (Generator shaft)
3,240 rpm (Combined unit)

5.2.2 Brushless Exciter

Equipment number EX-200
Manufacturer Fuji Electric Systems
Type GJG3218F-12
Output 450 kW
Voltage DC 460 Volt
Current DC 978 Ampere
Insulation class F

5.2.3 Permanent Magnet Generator

Equipment number PMG-200
Manufacturer Fuji Electric Systems
Type GDP2096T-06
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Output 5 kVA
Frequency 300 Hz
Poles 12
Voltage 220 Volt
Current 13.1 Ampere
Insulation class F

5.2.4 Generator Air Cooler

Equipment number GAC-200A, GAC-200B, GAC-200C, GAC-200D
Quantity 4 x 33.4%
Manufacturer Tada Electric
Model No. NPF
Type NPF (38)-424
Design flow 4900 l/min for four coolers
Operating pressure 3.0 bar gauge
Temperature Air (fin side): 71.3 °C (inlet) / 32.0 °C
Water (tube side): 23.5 °C (inlet, max.) / 28.5 °C (outlet)

5.2.5 Automatic Voltage Regulator

Equipment number AVR-200
Type Digital
Quantity One set of redundant control systems
Manufacturer Fuji Electric Systems
Voltage setting range -20% to +10%
Drooping rate 0 % (initial setting value)
Control accuracy ± 0.2% or less

5.2.6 Isolated Phase Bus

Equipment number BD-200
Quantity One
Manufacturer Simelectro
IPB Material Aluminum
Power freq. withstand voltage 38kV (1 minute)
Impulse withstand voltage 95 kV
Rated current 6,300 A main bus
1000 A branch bus
Short duration current (3 sec) 50 kA main bus
91 kA branch bus
Short duration current (peak) 200 kA main bus
300 kA branch bus

5.2.7 Generator Circuit Breaker with Disconnecting Switch and Earthing Switch
Equipment number GCB-200
Quantity One
Manufacturer Japan AE Power Systems
Type FPTD-20XM-100 HAG
Rated impulse withstand voltage 110 kV peak
Frequency withstand voltage 50 kV (1 minute)
Rated interrupting current 50 kA
Rated interrupting time 5 cycle
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Rated current 6300 A

Rated maximum voltage 17.5 kV
Duration of the short circuit 3 sec

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6. TRANSFORMERS

6.1 System Design

6.1.1 Generator Transformer
The 134 MVA PT. PAUWELS transformer is a three-phase oil insulated unit. The oil circulation is
natural with natural or forced cooling applied to the oil radiators. The transformer and tap changer
have separate oil conservator tanks and Buchholz relays. The surge arrester per phase is mounted on
the top of the transformer.
Cooler controls and temperature monitors are all contained in a marshalling control box.

6.1.2 Unit Transformer

The 12 MVA DAIHEN transformer is a three-phase oil insulated unit. The oil circulation is natural
with natural or forced cooling applied to the oil radiators. The transformer and tap changer have sepa-
rate oil conservator tanks and Buchholz relays.
Cooler controls and temperature monitors are all contained in a marshalling control box.

6.1.3 Service Transformers

The 2.3 MVA & 2.0 MVA PT. UNINDO transformers are three-phase oil insulated units. The oil cir-
culation is natural cooling applied to the oil radiators.

6.2 Equipment Data

6.2.1 Generator Transformer
Equipment number TR-200
Manufacturer PT. Pauwels Trafo Asia
Type Oil Immersed outdoor use
Cooling Type ONAN / ONAF
Capacity 92 / 134 MVA (ONAN / ONAF)
Voltage 13.8 / F142.500 - F144.375 - F146.250 - F148.125 - R150.000 -
F151.875 - F153.750 - F155.625 - F157.500 - F159.375 - F161.250
- F163.125 - F165.000 kV
Vector Group YNd1
Impedance Voltage 15% at 134 MVA

6.2.2 Unit Transformer

Equipment number TR-201
Manufacturer Daihen Electric
Type Oil immersed outdoor use
Cooling Type ONAN / ONAF
Capacity 8.5 / 12 MVA (ONAN / ONAF)
Voltage F15.180 - F15.007 - F14.835 - F14.662 - F14..490 - F14.317 -
F14.145 - F13.972 - R13.800 - R13.627 - R13.455 - R13.282 -
R13.110 - R12.937 - R12.765 - R12.592 - R12.420 / 6.3 kV
Vector Group YNd1
Impedance Voltage 5.5% at 12 MVA

6.2.3 Unit-2 C/T Service Transformer

Equipment number TR-202
Manufacturer PT. Unindo
Type Oil immersed outdoor use
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Cooling Type ONAN

Capacity 2.3 MVA
Voltage F6.6150 - F6.4575 - R6.3000 - F6.1425 - F5.9850 / 0.4kV
Vector Group YNd1
Impedance Voltage 8.1% at 2.3 MVA

6.2.4 Unit-2 Service Transformer

Equipment number TR-203
Manufacturer PT. Unindo
Type Oil immersed outdoor use
Cooling Type ONAN
Capacity 2.0 MVA
Voltage F6.6150 - F6.4575 - R6.3000 - F6.1425 - F5.9850 / 0.4kV
Vector Group YNd1
Impedance Voltage 9.09% at 2.3 MVA

6.2.5 LV Bus Duct

Equipment number BD-201, BD-202
Manufacturer Furukawa Electric
Rated current 3500 A (BD-201) / 3000 A (BD-202)
Rated voltage 0.6 kV

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7. CONDENSATE & CIRCULATING COOLING WATER SYSTEM

7.1 System Design

The direct contact condenser is a spray jet type. The circulating water flows through the distribution nozzles
where direct contact of the exhaust steam and circulating water occurs. As the steam is condensed, the mix-
ture of condensate and circulating water is collected in the main condenser hotwell and circulated to the
cooling tower by the hotwell pumps. Non-condensable gases not absorbed into the condensate are extracted
from the condenser by the non-condensable gas removal system (GRS) to maintain 0.11 bara of vacuum
pressure at the design conditions.
The main condenser serves primarily to condense the steam as it leaves the turbine. In addition to serving its
primary purpose of condensing turbine steam, the main condenser serves a secondary function as the collec-
tion point for the flowing condensate streams:
z Gland steam pressure steam trap drain
z Turbine steam system drain
z GRS inter/after condenser drain
The circulating water system removes heat from the main condenser and rejects this heat to the atmosphere
by means of an eight cell counter flow type cooling tower.
The circulating cooling water system originates at the cooling tower basin. The cooling tower basin also
supplies water to the auxiliary water pumps for the GRS, auxiliary cooling water system and fire protection
system. The basin level is maintained with makeup provided by the water supply system and the system
blowdowns directed into reinjection system. The blowdown rate changes depending on the prevailing ambi-
ent conditions and plant output.
The cooled circulating water flows by gravity and pressure difference through the direct contact main con-
densers spray jets. Cooling tower bay is equipped with two screens arranged in series to protect the con-
densers' distribution spray jet nozzles, the hotwell pumps and the fire pumps from debris. The screens are
equipped with the on-line cleaning system with a cleaning pump and underwater camera.
As mentioned earlier two 50% hotwell pumps are provided to deliver the circulating cooling water through
the counter flow cooling tower. The pumps discharge piping feeds into a common header and is distributed
into the cooling towers eight individual cells. The supply line is provided with an ultrasonic flow metering
on the exposed portion of the line near the tower. A siphon breaker is installed to immediately shut off the
water flow to the condenser in the event of both hotwell pumps stop or condenser water level very high.
Two 48-inch butterfly valves are also provided to condenser’s distribution lines. The circulating water rate is
measured and recorded continuously on the DCS by the flow meter element A2-FE-1001 ,temperature ele-
ment A2-TE1001 and pH meter A2-AT-1000.
The cooling water discharge from the main condenser flows into a 316L stainless steel distribution header
and splits to the two pump suctions with motorized isolation valves. Each pump is provided with two control
valves, one of which is intended for minimum flow and re-routed back into the main condenser through a
restriction orifice. The pumps discharge header lines become fiberglass below grade and up to the cooling
tower distribution header.
Just downstream of the stainless/fiberglass material split, the circulating water condenser’s outlet tempera-
ture is measured and recorded via temperature element A2-TE-1050 and continuously monitored on the
DCS. The condenser pressure and temperature are also monitored and recorded on the DCS via pressure
transmitter A2-PIT-1011/1012/1013 and temperature element A2-TE-1010.
The cooling tower fans (FN-209 - FN-216) draw air from the base of the tower and discharge this air
through the fan stacks. Each fan is driven by a totally enclosed speed reduction gear centered under the fan

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and an electric motor external to the stack.

In addition to its primary function, the cooling tower also serves as a distribution point for approximately
11,500 kg/h of non-condensable gases (NCG) from the gas removal system. The NCGs are effectively di-
luted to a fraction of their original concentration by the cooling tower exhaust. The gases are distributed to
the each cell by a FRP riser pipe and it is again divided into 8 pipes on the fan stack. In the event that on-
line maintenance of one or more cooling tower cells is required, the NCG stream can be routed to the stacks
of the other cells by closing the inlet valve on the riser pipe.
The chemical dosing system is supplied in order to neutralize the pH of the circulating water. The system is
consist of a concentrated NaOH tank, NaOH dilution tank and transfer / injection pumps. 20% sodium hy-
droxide (NaOH) is diluted from 48% NaOH automatically and injected at the discharge of the hotwell
pumps by the injection pumps. It is also possible to inject NaOH directly into the cooling tower basin and to
the condensate re-injection line. This system is a common facility for Unit 1 and 2, and the original two 12
liter/hour injection pumps are replaced with three 25 liter/hour pumps in the Unit 2 construction.

7.2 Control
The circulating water is controlled by the control valves 2-CCV-003A, B and maintains the condenser’s
hotwell level. In addition to these level control valves, on/off recirculation valves (2-CCV-004A, B) with re-
striction orifices are used during curtailed rates of operation.
There is no automatic run for the hotwell pumps. They are individually manually started from the DCS.
Each hotwell pump is interlocked with the discharge motor-operated control valve (2-CCV-002A, B). Each
valve closes automatically when the pump trips or is manually stopped. Condenser low level alarms are in-
dicated on the DCS via the level switch A2-LSLL-1020.
The water level of the cooling tower basin is maintained by the blowdown system connected to the SAGS
reinjection system. The blowdown is drawn out from the hotwell pump discharge with flows being con-
trolled by the control valve A2-CCV-007 with a flow meter and bypass.
The cooling tower fans are individually manually started from the DCS. The fans will automatically trip
when the vibration level gets too high. Vibration high alarms and the very high alarms are indicated on the
DCS.
The pH of circulating water is monitored by pH meter A2-AT-1000 and quantity of NaOH is adjusted by the
injection pumps manually.

7.3 Equipment Data

7.3.1 Main Condenser
Equipment number CO-200
Manufacturer Fuji Electric Systems
Type Direct contact, spray jet
Total heat duty 1.626 x 109 kJ/hr
Rated pressure 0.11 bara
Circulating water flow 17,900 m3/hr
Circulating water temperature 22.5 °C
Condenser outlet temperature 44.2 °C

7.3.2 Hotwell Pump

Equipment number P-205A, P-205B
Quantity 2 x 50% per Unit
Manufacturer DMW
Model number VPFO-W-M

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Type Vertical centrifugal canned type

Capacity @ rated head of 25 m 10,500 t/hr
Available NPSH 7.4 m
Required NPSH 5.9 m
Pump seal Mechanical
Speed 490 rpm
Pump Efficiency 86 %
Driver Rated Output 920 kW

7.3.3 Cooling Tower

Equipment number CT-200
Quantity 8-cells per unit
Manufacturer SPX Cooling Technologies
Model number F489A-6.60-8B
Type Industrial fiberglass Counter-flow mechanical draft
Circulating water flow 19,770 m3/hr
Design hot water temperature 44.2 °C
Design cold water temperature 22.5 °C
Design wet bulb temperature 17.0 oC
Drift loss 0.0010 % of the circulating flow
Evaporation loss of design 654.1 m3/hr
Nominal cell size 16.459 m x 14.630 m
Fill Film Fill

7.3.4 Cooling Tower Fan

Equipment number FN-209 - FN-216
Quantity 8 per unit
Manufacturer Marley Cooling Technologies
Model number 10MHP7-10
Design air flow per fan 793.2 m3/s
Number of blades per fan 10
Fan tip speed 56.69 m/s
Driver Data
Manufacturer TECO Westinghouse
Type Electrical motor, TEFC
Power Source AC380V 3 phase 50Hz
Rated horsepower 186.4 kW
Speed 1500 rpm (nominal)
Speed Reducer
Manufacturer Marley Cooling Technologies
Model number Series 4000, 12.98:1
Speed reduction ratio 12.98:1
Drive shaft
Manufacturer Addax
Model number LRC850.625 Shaft
Material Shaft: Carbon fiber / Coupling: 316 stainless steel

7.3.5 NaOH Injection Pump

Equipment number P-114A, P-114B, P-114C

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Type Metering pump

Manufacturer Nikkiso
Model number 1M1LA-VO. 2-30D1P
Capacity 25 liter/min
Material Casing: 316 stainless steel / Diaphragm: PTFE

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8. GAS REMOVAL SYSTEM

8.1 System Design

The purpose of the hybrid type gas removal system is to remove non-condensable gases (NCG) from the
main condenser that accumulates as the incoming steam condenses.
NCG is taken separately off the gas cooling zones of the main condenser (CO-200). NCG from the main
condenser gas cooling zones flows first through the first stage ejectors (EJ-202 and EJ-203, and/or EJ-201
when the back-up train operates).
NCG and the ejector motive steam are mixed, condensed and separated in the direct contact inter-condensers
(E-202 and E-203, and/or E-201) where the separated NCG flows through the second stage ejectors (EJ-205
and EJ-206, and/or EJ-204). Again the combined NCG and motive steam in the second stage ejectors are
condensed and separated in the direct contact after-condensers (E-205 and E-206, and/or E-204). Finally the
separated NCG from the after-condensers is extracted through the vacuum pumps (EJ-207 and EJ-208) and
separated at the separators (SEP-209 and SEP-210). The NCG is then combined into a header and routed to
the cooling tower fan stacks. The gland steam systems exhaust are also tied-in to this gas removal system.
Mixture of the condensed motive steam and cooling water from all two stages of the ejector systems are
routed back to the main condenser.
A U-seal is provided on each return line to prevent a siphoning effect in the system.

8.2 Control
The GRS motive steam lines are equipped with the pneumatic operated stop valves (2-ASV-101A/B/C) on
each train of two stages. Similarly, the non condensable gases lines are equipped with the motor operated
valves (2-CVV-001A/B/C).
The cooling water lines for the inter/after condensers are equipped with the motor operated stop valves (2-
ACWV-008A/B/C).
When either of the hybrid trains need to be stopped, operator(s) can switch to the back up ejector train
manually remotely from the DCS.
When flow rate of NCG to be extracted is smaller than 50% of the rated capacity of GRS, it is possible to
operate the power plant with one train only. However, special cares must be paid during such operation
since a single failure on the GRS operation may cause total loss of gas extraction ability for a certain period
required for startup of another train.

8.3 Equipment Data

Manufacture Gardner Denver Nash
Operating steam pressure 9.0 bara
Gas suction pressure 0.098 bara at 1st stage ejector inlet
Gas suction temperature 26.5 °C at 1st stage ejector inlet
Capacity NCG: 11518 kg/hr / Steam: 2893 kg/hr / Air: 489 kg/hr

8.3.1 First Stage Ejector

Equipment number EJ-202, EJ-203
Nozzle size 30" x 30"
Motive steam rate 5647.5 kg/hr

8.3.2 Second Stage Ejector

Equipment number EJ-205, EJ-206
Nozzle size 16" x 18"

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Motive steam rate 5605.0 kg/hr

8.3.3 Vacuum Pump

Equipment number EJ-207, EJ-208
Speed 484 rpm
Motor input power 230 kW
Seal water 18 m3/hr

8.3.4 First Stage Ejector (Back-up)

Equipment number EJ-201
Nozzle size 30" x 30"
Motive steam rate 8775.0 kg/hr

8.3.5 Second Stage Ejector (Back-up)

Equipment number EJ-204
Nozzle size 16" x 18"
Motive steam rate 9954.6 kg/hr

8.3.6 Inter-condenser
Equipment number E-202, E-203
Type Direct contact
Size 60" (1524.0 mm) diameter, 217" (5511.8 mm) height
Gas inlet / outlet 30" / 16"
Water inlet / outlet 12" / 20"

8.3.7 After-condenser
Equipment number E-205, E-206
Type Direct contact
Size 42" (1066.8 mm) diameter, 173" (4394.2 mm) height
Gas inlet / outlet 18" / 14"
Water inlet / outlet 8" / 16"

8.3.8 Inter-condenser (Back-up)

Equipment number E-201
Type Direct contact
Size 48" (1219.2 mm) diameter, 191" (4851.4 mm) height
Gas inlet / outlet 30" / 16"
Water inlet / outlet 10" / 16"

8.3.9 After-condenser
Equipment number E-204
Type Direct contact
Size 42" (1066.8 mm) diameter, 173" (4394.2 mm) height
Gas inlet / outlet 18" / 12"
Water inlet / outlet 8" / 16"

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9. AUXILIARY COOLING WATER SYSTEM

9.1 System Design

The auxiliary cooling water system removes heat from gas removal system inter/after condensers, the lube
oil coolers and the generator air coolers.
The auxiliary cooling water system takes its water from the main cooling water supply line upstream of the
siphon breakers. Either one of two 100% auxiliary cooling water pumps supplies cooling water for the gas
removal system inter/after condensers, the turbine oil coolers and generator air coolers and steam quenching
water for the steam drain chamber and the hotwell pump mechanical seal. Each auxiliary cooling water
pump is equipped with an integrated strainer which allows on-line cleaning.
The pressures at the suction and discharge of the individual auxiliary cooling water pumps are indicated lo-
cally. In addition, the discharge pressure is continuously recorded and monitored on the DCS and inter-
locked with the automatic start of the standby auxiliary water pump.
The cooling water for the gas removal system inter/after condensers, after mixing with the condensed mo-
tive steam, returns back into the main condenser. On the other hand, the cooling water used for the lube oil
and generator air coolers are routed into the cooling tower basin.

9.2 Control
The auxiliary cooling water pumps are individually manually started from the DCS.
The standby pump starts automatically on low discharge header pressure by a pressure switch (A2-PSL-
1310). A low discharge pressure can occur when the running pump trips or is not properly functioning.
The auxiliary cooling water flow rates through the lube oil coolers and generator air coolers are controlled
by restriction orifices located at each cooler header outlet.

9.3 Equipment Data

9.3.1 Auxiliary Cooling Water Pumps
Equipment number P-206A, P-206B
Quantity 2 x 100%
Manufacturer DMW
Model number DF-SB-M
Capacity @ rated head of 23 m 1800 t/hr
Available NPSH 11.8 m
Required NPSH 6m
Pump seal Cartridge type
Speed 1000 rpm
Pump Efficiency 81 %
Driver Rated Output 160 kW

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10. FIRE PROTECTION SYSTEM

The existing fire protection system, which was provided in the Unit 1 construction, is commonly used for
Unit 2. The deluge type water spray systems for the following locations are added for Unit 2.
¾ Generator transformer, unit transformer and service transformers (outdoor)
¾ Lube oil console (in the turbine building)
For the lube oil console, a pre-action system is also added at the mezzanine floor of turbine building.
The cooling tower has heat detection system on each fan cylinder and a horn and strobe light will operate in
case of fire detected.
And linear heat detectors are installed on the power cable trays and connected to the existing modules.

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11. INSTRUMENT AND UTILITY AIR SYSTEM

The existing instrument and utility air system, which was provided in the Unit 1 construction, is commonly
used for Unit 2.
Due to the larger instrument air consumption compared to the original design, following changes were made:
¾ One 6 m3 air receiver was additionally provided.
¾ The air dryer is to be manually stopped when outage of the air compressors happens.
As a result, air flow was changed as shown below.

Before modification

Unit 2
Air
Receiver header
Dryer
(A)

Receiver
Dryer Unit 1
(B)
Air
header

Unit 2 Utility Air

from Compressor
Unit 1 Utility Air

After modification
Bypass lines to enable dried air
supply after the dryer stop

Unit 2
Air
Receiver header
Dryer
(A)

Receiver
(B) Dryer Unit 1
Air
header

Receiver
Unit 2 Utility Air
(C)
Unit 1 Utility Air

from Compressor

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12. ELECTRICAL SYSTEM

12.1 System Design

The system is configured to supply electricity to the auxiliary loads and station services. Part of the output
from the turbo-generator is distributed to the system through Unit Transformer (TR-201), stepped down to
6.3kV from 13.8kV. The 6.3kV power is provided to some large plant auxiliaries as well as to the SAGS
electrical system, then stepped down to 380V through the service transformers (TR-202, 203). The 380V
power is distributed to the auxiliary loads, 380V motor control centers, 380V/220V distribution boards and
125V/230V DC&UPS systems.
In this clause, "existing" means the equipment installed in the Unit 1 construction.

12.1.1 6.3kV System

The system consists of 6.3kV AC Unit-2 Switchgear, in addition to the existing 6.3kV AC Unit-1
Switchgear and 6.3kV AC Station Switchgear. The switchgears are metal-clad type, all of their parts
are completely enclosed within grounded metal barriers. Secondary control devices and primary cir-
cuits are isolated from each other by shutters or barriers.
Primary bus and joints are completely encased with insulation materials to suit the voltage class of the
equipment.
Indoor equipment is arranged with the circuit breaker compartment behind the instrument panel. The
hinged instrument panel is opened to provide access to the circuit breaker.

12.1.2 380V System

The system consists of 380V AC Unit-2 Switchgear and 380V AC Unit-2 C/T Switchgear, in addition
to the existing 380V AC switchgears. Power for the cooling tower fans, auxiliary cooling water
pumps and fire pump is provided by this system.
380V AC Station Switchgear, one of the existing 380 switchgears, is connected with the emergency
diesel generator, therefore any essential loads are fed by this switchgear.
The switchgears are metal-clad type similar to the 6.3kV switchgears.

12.1.3 380V Motor Control Center

The system consists of 380V AC Unit-2 Motor Control Center, in addition to the existing 380V AC
motor control centers, to provide power for the low voltage & small capacity plant auxiliaries.
All components of the motor control centers are mounted on the plug-in starter chassis, which com-
prises of MCCB, fuses, contactors, thermal overload relays, connectors and command device modules.
The control supply is obtained from main power connections on all starter units of the stab-on type.
These stabs are tin plated and are fitted with the back up springs to provide constant contact pressure.
Motor load terminals are also of the stab-on type. Control terminals are disconnect plug and socket
type.
The existing 380V AC Station No.1 Motor Control Center and 380V AC Station No.2 Motor Control
Center can be fed by the emergency diesel generator through 380V AC Station Switchgear, therefore
the auxiliaries essential for the plant operation and emergency shutdown are connected to these motor
control centers.

12.1.4 125V/230V DC&UPS System

The system consists of batteries, battery chargers, UPS and distribution boards.
The system provides 125V DC and 110V AC control power sources for DCS, control panels and elec-
trical cubicles. Also the DC motor starting panel is fed by 230V DC system to operate Emergency Oil
Pump for the turbine.
The batteries have capacity to supply necessary power for two hours.
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12.1.5 380V/220V System

The system consists of the existing 380V/220V AC Station Distribution Board, which comprises of
MCCB, fuses and transformers.
The system provides power for the low voltage devices, lightings, space heaters and other miscellane-
ous loads.

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