Stator liquid cooling Flashcards
(30 cards)
What is the purpose of the Stator liquid cooling system?
to supply high purity, low conductivity cooling water to -
Main Generator Stator windings
Main Generator High Voltage Bushings
Main Generator Field Power Rectifiers
Describe The Function And Location Of The Following Stator Liquid Cooling System Component: Storage Tank
Space for variations in water volume
Maintains NPSH for Stator Cooling Water Pumps
Removes and vents gases
Make-up from condensate make-up and draw off is manual
Describe The Function Of The Pumps (3GMC P1A / P1B) and what busses they run on
To keep the required pressure. One pump is running while the other is on standby. 32D and 32L.
Describe The Function And Location Of The Following Stator Liquid Cooling System Component: Coolers
Describe The Function and Location of the Deionizer
Maintains low electrical conductivity
Removes dissolved mineral salts
Describe The Function and Location of the:
Temperature Control Valve (3GMC-TV36)
Mixes water through Heat Exchangers with Bypass water
Maintains temps between 104F-113F
Valve fails to “MAX Cooling” on loss of air
Describe The Function and Location of the: Pressure Control Valve (3GMC-PDC-37)
Maintains Stator Cooling Pressure 3 psi lower than generator hydrogen pressure
Why do we want to minimize bubble formation and gas pockets in the stator windings?
These would cause local hot spots
What happens to this valve on loss of air?
Fails open
Describe the purpose of the filters and when they should be replaced.
Filtering out particles larger than 10 microns, should be replaced at the first scheduled shutdown after the filter d/p reaches a setpoint or 18-20 months of service.
How many filters are there?
3 - one that leads to the stator windings, another through which make-up water is introduced and a 3rd ahead of the exciter static rectifiers and high voltage bushings to provide filtration for those components.
Describe the purpose of the Strainers and how many of them are there?
to strain out any foreign material. There are 2 of them - one is located at the inlet stator water near the generator and the other is located at the deionizer outlet
Describe The Function And Location Of The Following Stator Liquid Cooling System Component: Generator Bushings And Rectifiers Flow Control Valves
What are the 4 flow paths and their GPM?
Generator Stator Windings ~ 850 GPM
Exciter Rectifier Assemblies ~ 40 – 45 GPM
Generator High Voltage Bushings ~ 40 – 45 GPM
Stator Coolant Deionizer ~ 100 GPM
What cools the heat exchangers in this system?
CCS
Stator cooling water provides a heat sink to what components?
Exciter Rectifier assemblies and generator high voltage bushings.
At what two points is the conductivity of the Stator Cooling System monitored?
- the supply line to the stator windings downstream of the pressure regulating valve
- the return line from the stator winding where it enters the storage tank
Where is the Stator Cooling Panel located?
14’6” of the turbine building
What are the functions of the Stator Leak Monitoring System (SLMS)? There are two of them
One is for online detection of winding leaks, and the other is for maintaining cooling water O2 content.
How does this system operate during NORMAL OPERATION?
The stator cooling system should be in continuous operation during normal plant operation. System maintenance requires stator cooling system shutdown with the generator shutdown. One stator cooling water pump will be in continuous service with the other pump in automatic [standby]. Also, the stator cooling water deionizer will be in continuous operation except for short duration shutdowns for maintenance.
What are the major malfunctions of the stator cooling system?
High conductivity
stator cooling supply pressure low
stator cooling outlet temp high
stator cooling flow low
AND
anytime CCS experiences flow or temperature problems
What does the current/flow comparator do?
Protects the stator from low flow conditions by continuously monitoring and comparing stator coolant flow to stator winding current
When will the stator leak monitoring trouble “SCP 3-4” alarm be generated?
whenever calculated H2 leakage exceeds 10 to 20 cubic feet per day (adjustable).
What is a turbine generator runback and what are the circumstances that we would need to enact it?
It is about removing a load from the generator to protect it from damage
1. Stator water return temperature - High.
2. Stator inlet water pressure - Low.
3. Stator coolant flow - 15% less than required for stator amps. Flow FS63 to Amps
