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CO, SO, CE, Gen H2, OW, RD, CM > Stator And Isophase Bus Cooling > Flashcards

Stator And Isophase Bus Cooling Flashcards

0
Q

What does the isophase bus cooling system provide cooling for?

A

Electrical buses from the main gen terminals
Main power transformer
UAT

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1
Q

What does the stator cooling water provide cooling to?

A

Main gen stator windings
Gen bushings
Rectifier excitation system
Gen lower frame extension

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2
Q

Describe the stator cooling system flowpath.

A

2-100% capacity pumps in parallel, two coolers in series, tank, filter, generator.

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3
Q

What provides continuous purification for the stator cooling water?

A

Deionizer by means of a bypass line from the cooler outlet to the storage tank.

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4
Q

What flows through the tubes in the stator cooling water coolers?

A

Turbine cooling water.

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5
Q

What is the arrangement of the stator cooling water cooler?

A

Can be parallel or series.

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6
Q

Describe the flowpath of the isophase cooling system.

A

Motor driven fan, air to water HX, 2-100% redundant units, both are normally in service at the same time.

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7
Q

What provides power to the pump motors?

A

NG

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8
Q

What provides power to the local annunciator and generator trip relays?

A

NKN-M45

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9
Q

What is the makeup water source for stator cooling?

A

DW

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10
Q

What provides cooling water to the collector housing heat exchanger?

A

Normal chilled WC

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11
Q

Where are the stator cooling water pumps located?

A

140’ of the turbine building

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12
Q

What causes the standby stator cooling water pumps to auto start?

A

If the in service pump’s discharge pressure drops below a given set point.

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13
Q

Describe the capacity and quality of the stator cooling water pumps.

A

80% capacity, shell and tube HX,

In series on the shell (stator water) side and in parallel on the tube side.

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14
Q

Whay are the duplex strainers used?

A

Allows for switching out the clogged strainer while still maintaining operation

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15
Q

What is the purpose of the stator cooling water storage tank?

A

Mounted at a sufficient height to provide NPSH for the stator cooling water pumps.

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16
Q

Describe the stator cooling filters.

A

Replaceable cotton wound cartridge filters

Located at the generator inlet and rectifier inlet.

High dP alarms at the local panel.

17
Q

Why does the stator cooling line have a deionizer?

A

Maintains low electrical conductivity by continuously deionizing 10% of stator cooling water flow stream.

18
Q

Where are the stator cooling test valve control switches located?

A

Two push buttons, one in control room, one at local control panel.
Button contact must be maintained throughout test for it to occur.

19
Q

How can the pumps running from auto start be stopped?

A

Must be stopped manually unless they are locked out by a generator trip.

20
Q

How is the stator cooling water pressure control valve controlled?

A

It isn’t… It’s locked in a throttled position that maintains 60 psig.

21
Q

How is the Stator cooling water temperature control valve controlled

A

Pneumatically operated 3-way valve at the outlet of stator water cooler B.
TV-33 controls bypass flow around stator cooling water HX to maintain 42*C

22
Q

In what position does the stator cooling temperature control valve fail on loss of air signal?

A

Fails to the full cooling (no bypass) position

23
Q

Describe the isophase bus cooling coils.

A

Air to water HX, multi row, multi fin,

24
Q

What provides cooling water to the isophase bus cooling coils?

A

Turbine cooling.

Flow rate and cooling rate is controlled by MANUALLY adjusting the cooler outlet valve.

25
Q

Where are the isophase bus cooling coils located

A

140’ turbine building

26
Q

Describe the isophase cooling air blowers.

A

2-100% capacity,

Both normally in service but one can be removed for maintenance.

27
Q

How are the isophase cooling air blowers started?

A

Locally by MANUALLY operated start/stop switches on the load center supply breakers.

28
Q

Where are the isophase cooling air blowers located?

A

140’ turbine building

29
Q

What is the power supply for the isophase cooling air blowers?

A

NG

30
Q

How is the collector housing unit cooled?

A

It has it’s own HX.

1 HX that is cooled by a fan that is attached to the main shaft of the generator.

31
Q

What is the purpose of the collector housing cooling HX?

A

Keeps the collector housing cool to prevent damage to the brushes.
WC tube side. Collector air outside.

32
Q

What system is used to monitor for a stator leak?

A

Stator leak monitor system.

33
Q

How does the slms detect a leak?

A

Monitors the tank vent for evidence of hydrogen.

34
Q

How many stator cooling pumps are there and how many are normally in operation.

A

2-100% capacity, one in standby

35
Q

Where is the stator cooler system normally operated from?

A

The control room.

36
Q

Where is the hydrogen that is collected in the stator cooling water released to?

A

It is released into the the coolant tank where it is vented to atmosphere through a vent line that has an S-loop

37
Q

What happens to the plant if a stator cooling primary sensor is actuated?

A

We have 70 seconds to return the sensor to normal or a turbine and generator trip will occur.

38
Q

What happens if isophase bus cooling is lost?

A

We have thirty minutes of run time without causing permanent damage or weakening of the bus material.

39
Q

What will happen to the stator cooling if TC is lost?

A

Stator cooling temperatures will increase until reaching a turbine generator trip.

40
Q

What will happen to isophase bus cooling if TC is lost to both coolers?

A

Will require a load reduction to maintain temperatures within limits.

41
Q

What happens if power is lost to both stator cooling water pumps?

A

Turbine generator trip.

CO, SO, CE, Gen H2, OW, RD, CM (7 decks)

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