Control Oil (CO) Flashcards
What is the purpose of the CO system?
Provide pressurized hydraulic fluid for the operation of:
- Main Steam Control Valves
- Main Steam Stop Valves
- Combine Intermediate Valves
- Electrohydraulic Control System
When is the Transfer Filtering Pump used?
When fluid in the reservoir is being filled or drained or for bypass filtering of reservoir fluid when the Hydraulic Pumps are shut down
What system provides cooling for the Control Oil Hydraulic coolers?
TC
What system powers the Main Hydraulic pumps?
NG
What happens if power is lost to the Hydraulic Pumps?
Turbine will trip on low oil pressure
What system powers the filter pump motor?
NH
What does NN do for the CO system?
Provides power to the EHC control cabinet
How is the Hydraulic Oil Cooler affected by a loss of IA? Operator actions?
TC control valves will fail open to the Hydraulic Oil Coolers
Operator will have to throttle open the bypass around the temperature control valve and then isolate the control valve.
Also goes to the CO Reservoir dryer/conditioner
What is the capacity of the Hydraulic Fluid Reservoir?
800 gallons of EHC fluid
What maintains the temperature of the Reservoir and how is it controlled?
Two electric-fan units, operated automatically by a thermostatic control in the power unit
Why is the Reservoir also equipped with temperature controllers?
They control position of the Hydraulic Fluid Coolers Cooling Water Inlet Valves such that the hydraulic fluid entering the reservoir is ~115F
Concerning the Reservoir Heater/Fan controls, what happens when the switch is taken to START? Auto?
Start: Fans will start, but the heaters will
not energize regardless of Reservoir
temperature
Auto: If temperature of hydraulic fluid is
<85F, the fans will start and the heaters
will energize
- Fans and heaters will continue to
operate until the temperature of the
hydraulic fluid is above 85F, at which
time the heaters will de-energize and the
fans will continue to operate for ~10
minutes to cool the heaters
What is the capacity of the Main Hydraulic Pumps?
100% capacity each
How do the pumps respond to system demand changes?
The pump will vary its stroke to meet the flow demand and maintain constant pressure
The pump will stroke to zero delivery when dead headed
What is the purpose of the auxiliary pump mounted into the main pump housing?
Takes suction on the control oil reservoir and supplies cooling and lubrication to the main pump
What would cause the standby Main Hydraulic pump to auto start?
If system pressure falls to 1300 psi
Where are the pumps normally operated from and where are they located?
Control room
100’ Turbine Building
How much nitrogen is charged into the Accumulators?
1000 psig
What is the purpose of the Accumulators?
Provide an immediate 200% reserve of fluid for transient flow requirements
What is the capacity of the two Hydraulic fluid coolers and what cools them?
100% capacity each
Cooled by TC
To what temperature range does the Hydraulic Fluid cooler maintain the fluid at?
110 - 125F
What temperatures would sound an alarm in the Control Room?
High temp of 130f or low temp of 85F
What is the purpose of the Air Dryer? How does it perform this function?
Removes moisture from the air breathed by the Hydraulic Fluid Reservoir during power unit operation
Air passing through the dryer is treated by layers of activated alumina to remove any moisture
Before entering the reservoir, the air is filtered by a .5 micron automotive type disposable treated paper filter element
What color does the alumina turn when it has become saturated with moisture, requiring replacement?
Pink
What system assists with the motive force in the Air Dryer?
IA
What kind of pump is the Transfer Filter Pump?
Hydraulically balanced cartridge type vane pump (fancy way of saying rotary positive displacement pump)
How does the Transfer Filter Pump operate to move fluid?
Fluid is captured between “vanes” in a low pressure larger region of the pump casing and forced out at a higher pressure in a smaller region of the pump casing
What different uses do I have for this pump?
Used to provide control oil flow through the Fuller Earth Filters for oil purification when the Hydraulic pumps are secured
Used periodically during power unit operation for bypass filtering of fluid in the reservoir or when adding fluid to the reservoir
What is the purpose of the Fullers Earth Filters?
Maintain Control Oil close to neutral pH level by neutralizing acids and absorbing water
Maintain chlorine content within specifications
What is Neutralization?
A chemical reaction that neutralizes the ionic charge on both the acidic and the basic properties of a solution
The effect is like removing the ions that are responsible for those properties
How do we prevent overpressurization of the Fullers Earth Filters?
System is equipped with relief valves set at 75 psig
One relief valve is located downstream of both the Hydraulic Fluid Filtering Pump and FCV-27 to ensure that overpressure protection is available regardless of the pumping source
When is the Fullers Earth Filtering system normally in service?
Continuous operation when the turbine is in service
What two important tasks are accomplished by the low pressure air purge in the Stealth EHC system?
It extracts moisture from the fluid while excluding other contaminants from getting into the system
How much of the rated discharge air of the membrane of the EHC system is used to transport moisture?
5 - 20%
What is the purpose of the Recirculating Tank?
5 gallon tank that serves as a vessel for batch mode purification independent of the rest of the system
Used during “caking” process after replacing Fuller Earth Filter elements, which allows the saturation of the filter media to ensure the media will fulfill its filtering function
What are the four possible configurations associated with CO-V204?
Closed
Discharge
Recirculate to Fluid Reservoir
Discharge to Recirculating Tank
Where can I test the auto start capability of the Main Hydraulic Fluid pumps?
Performed locally at the CO skid and is coordinated with the Control Room during system startup before the turbine is reset
At what system pressure will the Turbine trip at?
1100 psi ( 2 out of 3 logic)
During normal operation, how much of the fluid flow is bypassed to the Fuller Earth Filters for continuous cleanup?
5% (2.5 gpm)
How is the system affect by a loss of Instrument Air?
Electro Hydraulic Fluid Reservoir Temperature Control Valves fail open due to loss of air to the Temperature Indicating Controllers
Control Oil Reservoir Conditioner/Dryer would lose its air supply
EHC dryer would lose the required air supply
