Turbine Control Oil

Question 1

What are the three purpose/ functions of the Overspeed trip device?

Answer 1

• Mechanical overspeed protection trip (111%)
• Provide a means to test, reset and latch the turbine
• Prevent a spontanious relatch of the turbine following any depressurization of AST oil header (all trips trip overspeed trip device)

Question 2

What turbine trips does SV-171 open on?

Answer 2

• Rx trip (P-4, trn B)
• Gen trip (86G1 or G11)
• Gen loss of field
• AMSAC
• Manual (elec)
• *elec OVRSPD
• *loss of both Kepco P.S.
• *loss of all speed ch + PCB open
• *Low Cond Vac
• *Low Brng oil Press

*DEHC (tricon)

Question 3

What turbine trips does SV-37 open on?

Answer 3

• Rx trip (P-4, trn B)
• Gen trip (86G1 or G11)
• Gen loss of field
• AMSAC
• Manual (elec)
• *elec OVRSPD
• *loss of both Kepco P.S.
• *loss of all speed ch + PCB open
• *Low Cond Vac
• *Low Brng oil Press
• **SI
• **P-14

*DEHC (tricon)

**additional trips

Question 4

What turbine trips does SV-40 open on?

Answer 4

• SI
• P-14
• Low AST oil press (anything that causes PCV-23 to open, SV-37 trips, SV-171 trips, trip block trips, Mech ovrsp)

Question 5

What is the function of SV-38?

Answer 5

allow operators to remotely latch the Turbine

Question 6

What are the turbine trips that are not via an electronic soleniod valve?

Where to the trips actuate from?

Answer 6

• Thrust bearing trip - trip block, high backpressure pushes trip block lever and opens port draining ATS oil
• Low Bearing Oil trip - trip block, low oil press loses to spring press pulling trip block lever, opens port
• Mechanical overspeed - latch device
• Mech manual - latch device

Question 7

When a turbine trip is actuated, what is the mechanism that allows the CV, SV, RSV and IV to shut?

Answer 7

1. AST oil depressurizes
2. PCV-23 opens, depressurizing emergency trip header
3. this allows dump valve to open
4. open dump valve allows EHC oil to flow from valve actuator to two flow paths
   
   1. drain header back to EHC reservoir
   2. on top of valve actuator helping close valve
5. spring pressure and EHC assist close valve

Question 8

Brief description of following components

• SV-40
• SV-41 & 42
• SV-171
• PCV-23
• Dump valve
• SV-38
• SV-37

Answer 8

• 40- B/U interface valve (any turbine trip will trip SV-40)
• 41/42- overspeed and LDA vlvs, close CV and IV
• 171- provides turbine trip protection when turbine trip testing in progress
• 23- Auto stop oil interface valve (AST oil depress opens this valve, which will depress the Emerg trip header)
• dump- holds EHC pressure on turbine valve actuators
• 38- provides remote latch capability
• 37- provides all elec turbine trips on trip block

Question 9

Purpose of HP accumulators

Purpose of accumulators on valve actuator

Answer 9

• provides EHC pressure to system during pump switchover (press to 2000 psi with N₂)
• allows for pressure fluctuations during transients without overpressurizing system piping and process lines

Question 10

During turbine trip testing (test lever is in test) is it a concern if PI-230 is lowering with PI-205?

Answer 10

yes, abort the test. PI-205 should depressurize because that portion of the AST oil system is draining due to the turbine trip that is being tested

If PI-230 is lowering that means that the test lever is not doing its job and you will get an actual trip, because you are depressurizing all AST oil and PCV-23 will soon open

Question 11

What is the purpose of the the TEST solenoid valves

Answer 11

allows the testing of individual turbine valves at power

• test depressurizing a single valve actuator and prove the valve will close without depressurizing whole emergency trip header

Question 12

How is AST oil Press maintained during all plant conditions

Answer 12

MOP

HPSOP

2 relief valves