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40 Cards in this Set
- Front
- Back
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Main Suction Pump Auto start
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AUTO starts when MSOP suction pressure < 10 psig
Must be shutdown manually by taking Control Switch to STOP. |
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Turning Gear Oil Pump Auto Start
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AUTO starts when MSOP discharge pressure < 190 psig
OR Bearing oil pressure drops < 15 psig. Must be shutdown manually by taking Control Switch to STOP. |
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Emergency Bearing Oil Pump Auto Start
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AUTO starts when MSOP discharge pressure < 180 psig
AND TGOP discharge < 12 psig |
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Lift Pumps auto start
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All lift pumps AUTO start when the TGOP is started (develops discharge pressure) AND lift pump suction pressure is at least 4 psig.
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Generator Core Monitor
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Conductivity decrease to 60% or lower for 10 seconds
- Validation control unit auto initiates to deliver gas flow to a filter - A signal change confirms an overheating condition - No signal change generates a malfunction alarm. - Pyrolysate Collection Operation auto initiates - Gas flows to a collection chamber with a removable cartridge for testing. - Sampling results in a decrease in generator gas pressure. |
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Loss of stator water cooling runback initating conditions
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Stator cooling water stator inlet pressure low (<43 psig)
Stator water bulk outlet temperature high (>81 C) Main generator high voltage bushing cooling water flow low (< 84gpm) (2/3 trips): |
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Loss of stator water cooling runback automatic equiptment actions
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Runback EHC load set motor 21.4 (3 minutes)
IF FW flow is maintained > 6.7 Mlbm/hr (~44% steam flow) "A" Recirc pump trip (after 9 seconds) "B" Recirc pump trip (after 18 seconds) ** if FW flow drop below 6.7 Mlbm/hr before 9 or 18 sec then the respective pump wont trip** Main turbine trip timer trips main turbine if stator current is: > 26,173 amps after 2 minutes Or > 7,469 amps after 3.5 minutes |
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Steps for synchronization of main generator
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Exciter voltage regulator transfer in MANUAL and Manual
Voltage Control is at low limit. Close Exciter Field Breaker. Check Manual Voltage Regulator for proper operation. Adjust Main Generator terminal voltage to nominal 22KV. Place Exciter voltage regulator transfer in AUTO and ensure proper operation. Turn ON synchroscope for one Main Generator output breaker. Adjust Main Generator (Incoming) voltage so that it is slightly higher than running voltage. Adjust Main Generator speed (frequency) so that the synchroscope is rotating slowly in the FAST direction. Close Main Generator output breaker at 3 minutes before vertical. Increase Main Generator load until Main Turbine bypass valves close. Turn OFF synchroscope for Main Generator output breaker just closed and ON for other Main Generator output breaker. Place Sync. Check Relay key in BYPASS. Close the other Main Generator output breaker. Turn synchroscope OFF. |
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Main generator Sync. Check Relay
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Sync. Check Relay Requires:
- relative motion - 5 degrees from vertical |
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8 protection relays
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- Switch Yard / Line Protection – 386A and 386E
- Unit Transformer Protection – 386B and 386F - Main Generator Protection – 386C and 386G - Unit Aux Transformer Protection – 386D and 386H |
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Generator Lock out resulting actions
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- Trip the Main Generator Output Breakers
- Trip the Alterrex exciter field breaker - Trips the Main turbine - Auxiliary Bus Fast Transfer - Transfer of main generator voltage regulator to Manual - Trip Reactor Recirc pumps **(ONLY if powered by main generator) ** - Energize the Main Generator Output Breaker Failure Circuit. - Trip main unit transformer cooling units **(ONLY on Unit Transformer Protection Trips)** - Trip unit auxiliary transformer cooling units **(ONLY on Aux Transformer Protection Trips)** - Trip Stator Water Cooling pumps **(ONLY on:Main generator differential (different phase currents),Main generator neutral overcurrent, Main generator neutral overvoltage)** |
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Relationship between stator water cooling and hydrogen cooling and effect on generator
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Stator water cooling pressure is maintained 3 psi less than Hydrogen cooling system pressure to ensure any leakage results in air entering the stator water cooling system rather then cooling water exiting to the generator
As stator water cooling inlet pressure is reduced - cooling water flow rate is reduced - heat removal capability is reduced - stator overheating is possible |
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effect on generator on pressure decrease of the hydrogen water cooling system
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Stator water cooling pressure is maintained 3 psi less than Hydrogen cooling system pressure to ensure any leakage results in air entering the stator water cooling system rather then cooling water exiting to the generator
As stator water cooling inlet pressure is reduced - cooling water flow rate is reduced - heat removal capability is reduced - stator overheating is possible |
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effect on generator on pressure decrease of the hydrogen seal oil system
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Reduction in hydrogen seal oil pressure
Hydrogen will leak from main generator in to the seal oil system Results in hydrogen pressure decreasing |
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Power source to the alternator exciter
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DC power is supplied to rotor via a collector ring and brush assembly from either the external 125VDC source (for initial field flashing 10 sec *PP04) or by the Voltage Regulator.
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Exciter Field Rectifiers
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- Coverts AC power input from alternator-exciter to DC power for return to generate the exciter field.
- contains 2 parallel circuits, only 1 is required to support field current. - Automatic or Manual voltage regulators provide DC control signal. |
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Main Generator Field Rectifiers
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- Converts AC power input from alternator-exciter to DC power output to Main Generator Rotor
- Cooled by stator water cooling - contains 5 parallel sections, 4 are required for 100% power |
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DC manual voltage regulator operation
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o manually controls alternator terminal voltage to maintain a constant generator field voltage.
o Has three indicating lights Red – upper limit Yellow – 0 – 16% Green – lower limit |
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AC auto voltage regulator operation
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o Automatically controls exciter field voltage to maintain a constant generator terminal voltage.
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relationship between fireing time and field current
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- the greater the firing time of the greater the field current
- the shorter the firing time the lower the filed current |
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AC & DC regulators Unbalanced Alarm
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5% voltage difference between AUTO (AC) voltage regulator and MANUAL (DC) voltage regulator output voltage. Caused by Megawatt, load, or voltage fluctuations.
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Stator water cooling Temperature Control Valve (TCV)
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Controls SCW temperature downstream of the HX with in a band of 40-45°C
Controls by throttling the amount of flow that bypasses the HX. Downstream HX temp ↓ - more water bypasses Downstream HX temp ↑ - less water bypasses Service water flow to the 1 cooler & bypass line remains constant. |
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Stator water cooling Pressure Differential Control Valve (PDCV)
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Controls SCW pressure 3-5 psig less than generator H2 pressure to the stator cooling coils. To ensure SCW will not leak into the generator casing
Contains a min flow and max flow mechanical limit Minimum flow – 553 gpm (to prevent gas binding) Max flow – 711 gpm (to prevent excessive SWC pressure) |
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SCW Pump auto starts
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Standby pump Auto starts:
Low discharge pressure of 122 psi/112 psi Standby pump Switch in normal |
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SCW pump auto trips
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Pump trips on:
Manual control switch to stop Generator lock out due to o neutral overvoltage (could be caused by a leak) o neutral over current (could be caused by a leak) o differential (phase current) |
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Hydrogen Supply & Makeup
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Hydrogen supplied from the HWC system. Make up is required for main generator inerting following maintenance, H2 leakage through main generator shaft seals, and H2 entrainment in the seal oil.
Hydrogen is supplied through the Pressure Control Station control regulators - 90 psi for normal static pressure - 80 psi for dynamic pressure during make up - 100 psi for inerting. An excess flow check valve provides a means to isolate HWC if an excessive flow rate is established. - Isolates when flow rate exceeds 5776 scfh - H2 supply is still available via manual bypass |
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Hydrogen Gas Control
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Regulates the supply of hydrogen to the main generator casing. Contains gas pressure regulator, filter dryer, gas analyzer, and a flow meter.
The generator hydrogen fans supply motive force for sample flow. Continuously monitors - Hydrogen Purity - Hydrogen Pressure ( - Hydrogen temperature - Moisture content Supports purging the generator with CO2 and Instrument Air |
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* Gen Hydrogen and Seal Oil System Trouble alarm
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High hydrogen pressure in main generator – 77 psig
Low hydrogen pressure in main generator – 70 psig Low hydrogen purity in the main generator – 90% Hydrogen High Hydrogen temperature cooler outlet– 56C |
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why hydrogen is used as the medium for cooling the internal components of the main generator.
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Inexpensive
High thermal conductivity Less Windage Losses |
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Identify the control functions associated with the Emergency Seal Oil Pump.
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Auto starts on loss of MSOP (low discharge pressure < 110 psig) and Switch in AUTO
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Identify the control functions associated with the Isolated Phase Bus System fans.
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Normal operation on fan is running ("MANUAL") and one fan is in standby ("AUTO")
When control switch is placed in manual (If the other fan is NOT running) Damper will open → when full open (30-40 sec) fan will START When control switch is in AUTO The standby fan will auto start if running fan trips Fan Trips on - Low air flow ( 0.05 in H2O) - High return air temperature (176°F) - Trips are bypassed 30-40 seconds on a fan start to allow time for dampers to stroke and fan to establish flow. Bypass switch – will allow removal of standby fan breaker without tripping running fan. |
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Identify operator action on loss of Isophase Bus Cooling
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Restore Iso-Phase Bus Cooling
Reduce Reactive load to 0 MVARS If cooling will not be restored in ten minutes - Reduce reactor power until output current is < 20,000 amps - If temperatures can not be maintained less than 105°C - Trip Turbine |
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SSE - Evaporator Water Feed System
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controls input from condensate via a AOV level control valve & MOV shut off valve.
2.5" below normal level – Low level alarm in MCR - LCV air control valve modulates to control level to the desired setpoint - 2.5" above normal level – High Level Alarm in MCR - 4" above Normal Level – Shutoff MOV closes |
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SSE - Steam Seal Header Supply
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Steam Seal Header Supply - Controls steam supply to the loads.
- PCV regulates steam from the evaporator to maintain header pressure of 4 psig - < 4 psig downstream of the steam seal header PCV – aux steam supply PCV will open and alarm in MCR. No steam will be supplied until HV-07-*62 is opened. |
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SSE - Evaporator Steam Feed System
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Evaporator Steam Feed System - steam from extraction source to tube side
- Normal supply (high turbine load) – 3rd FWH extraction steam line (15th stage LP). - Two series BTVs controlled by Turbine relay dump valve (EHC) o When extraction steam pressure is 2.5 psid greater than header pressure than SV-07-*51 is energized and PV-07-*50, *51 are permitted to open. o When extraction steam pressure is 2.2 psid less than header pressure SV-07-*51 will be deenergized and PV-07-*50, *51 will be air assisted in closing. - A turbine trip signal from the EHC system or test switch HS-07-*51 taken to close will cause SV-07-*51 to deenergize. Test switch must be held in close, spring returns to normal. - S/U & S/D supply – from Main Steam lines C(U1)/B(U2) - PVC regulates steam flow from S/U S/D supply based input to the high pressure selector. o Normal – controls shell side pressure to 15 psig o SSE heating from cold condition – controls tube side pressure at 25 psig o Will auto CLOSE on 90% load from 3rd FWH extraction source (pressure high enough) o Will fail OPEN on a loss of instrument air. |
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SSE - Evaporator Drain System
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Evaporator Drain System – (tube side drain) controls Condensed water flows to the evaporator drain tank.
- Low level transmitter controls position of LCV drain valves to drain condensate to the 2nd FWHs - High level transmitter OPENS the LCV dump valve to drain condensate to HP condenser. |
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Steam Packing Exhauster and Isolation Valves & Fan
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Steam packing exhauster inlet valves OPEN:
- Condensate inlet and outlet valves must be full OPEN - SPE fan starts when associated inlets valve is 90% OPEN Steam packing exhauster inlet valves CLOSE - Hand Switch taken to CLOSE OR - when condensate inlet or outlet valve closes OR - When SPE fan is NOT running Fan Auto starts when condenser suction valve is > 90% open and trips when suction valve closes |
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effect of a loss of Sealing Steam
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Loss of sealing steam would require a rapid plant shutdown and breaking condenser vacuum. Maintaining vacuum would result in damage to all low pressure seals. With the turbine stop valves closed, all seals downstream would be experiencing vacuum conditions. Additionally, valve stems could warp or bow due to thermal stress caused by rapid cool-down.
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effect of a loss of Steam Packing Exhauster
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Operationally, loss of the steam packing exhaust header is no big deal. The only concern would be increasing airborne radiation levels in the turbine enclosure. This would be minimal because any steam leaking from a seal would be from the sealing steam header - unless it was badly worn.
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loads supplied by Extraction Steam and include from which stage of LP or HP turbine the steam is coming.
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6th FWH - 7th stage of HP turbine
5th FWH – cross around steam (exhaust from HP turbine) 4th FWH –13th stage of the LP turbine 3rd FWH –15th stage of the LP turbine 2nd FWH –17th stage of the LP turbine 1st FWH –19th stage of the LP turbine SSE – 15th stage of the turbine |
