EDG - .5 Flashcards
EDG Fuel specs.
Each EDG has two fuel oil storage tanks – 26,500 gallons each. Seven days at 4200KW requires 50,000 gallons of fuel.
EDG Rating
- Rated – 4430KW @ 0.8Pf 5538KVA
- 110% Overload (4873KW) can be maintained for 2 out of 24 consecutive hours
- 120% Overload (5316KW) can be maintained for 30 minutes.
Auto-start signals.
- LOP - Both incoming feeder voltages <92% AND
Bus voltage <70%. - Degraded Voltage - Both incoming feeders <92% for 20 seconds.
- LOCA - Core Spray logic
RPV Level -129” OR
Drywell Pressure 1.68psig OR Manual Core Spray Initiation
EDG BKR Close permissive.
- Diesel ready for Load - Frequency >57Hz (95%)
Voltage >3950V (95%) - Switchgear - Both Normal and Alternate feeder breakers open
- Bus voltage <70%
- DG Lockout Relays reset
Regular Lockout Relay (86R)
- Generator differential o/c
- Low Lube Oil Pressure
- Overspeed (engine)
- Bus differential o/c
- Emergency Stop PBs
Backup Lockout (86B)
- Generator Differential o/c
- Generator Phase o/c
Test Lockout (86T)
- Reverse Power
- Bus Overcurrent
- Low field current
- Over-excitation
What occurs when the Regular and Backup relays actuate?
- Trip and lockout the diesel engine
- Trip and lockout the EDG breaker
- Enable EDG breaker failure protection
What occurs when the EDG test lockout relay actuates?
- Trip and lockout diesel generator breaker
- Enable diesel generator breaker failure protection
(Test Lockout is B/P on an emergency start)
Breaker failure protection
- Trips the diesel
- Trips the normal and alternate feeder breakers.
The following occurs to the EDG when a LOCA occurs:
(Not the sequencer)
- All NORMAL Stops disabled (Emergency stops still work)
- Test Lockout Relay disabled
- Governor shifts to Isochronous (60Hz) and speed control is disabled (10C651)
- Voltage Regulator shifts to Isochronous (4160V) and voltage control is disabled (10C651)
- Opens EDG output breaker if running in TEST
Local Engine Control Switch positions & functions.
- Remote – Control from remote engine control panel or the control room.
- Local – Control Locally, all auto starts disabled.
- Maintenance – Control locally, all auto starts and excitation disabled.
How do you enable the remote Generator EMERGENCY TAKEOVER and what automatic action is taken away?
- Enables control of diesel and breaker from remote generator and engine control panels
- Diesel will not respond to a LOCA (LOP responds to < 70%bus voltage signal only)
What type of valve controls EDG LO Makeup operation, and how can you operate this valve in the case of a loss of power?
LO Makeup to the sump is controlled by a solenoid valve that fails close on a loss of power. It can be overridden locally with a control knob at the base of the valve.
EDG S/U Sequence:
0 RPM
- Cranking cycle timer initiate
- SACS cooling water valve opens
- Low Air start pressure alarms lockout
EDG S/U Sequence:
95 RPM
Starting air shutoff
EDG S/U Sequence:
>365 RPM
- Starting air shutoff
- Field flash (again)
- Low Lube oil pressure trip enabled
(indication after 7 sec TD)
EDG S/U Sequence:
>125 RPM
- Starting air shutoff (redundant)
- D/G Room Recirc fan armed
- Engine run timer starts
- JW &LO Hi Temp alarms disabled
- Motor driven fuel oil pump armed
- Motor driven rocker arm prelube pump armed
- LO Keep Warm heater shutdown
- JW Keepwarm pumps and heaters shutdown
- Generator Space heater shutdown
- Exciter field flash circuit activated
- Low starting air low pressure alarm re-activated
- Cranking timers de-energized
- “Diesel Running Not Loaded” light energized
EDG S/U Sequence:
>3950Vac
and >57Hz
EDG Ready to load permissive
Diesel Ready for Auto Start
- Remote/Local/Maintenance in Remote
- Normal/Emergency Takeover in Normal
- Shutdown relay not energized
- Diesel Generator Lockouts reset
- Barring Device not engaged
- Start Failure relay not energized
- 125VDC control power available (If control power is not available, EDG will not start)
EDG Recirc Fan Trips
- Overcurrent
- Undervoltage
- CO2
- Low Flow
When can an EDG be paralleled with another power source?
When in Test.
Anti-pumping circuit operation
IF a LOP were to occur within 2 seconds of a diesel breaker closure the breaker may not reclose after it trips due to the anti-pumping circuit. The operator will have to press the trip pushbutton and then close the breaker.
EDG Start time criteria.
EDGs are expected to start and reach rated voltage within 10 sec. 13 sec are allowed due to signal processing time.
SACS thru EDG HX Flow path.
Air Intercooler then Jacket Water then Lube Oil.
Why is the Rocker Arm LO system separate?
Rocker Arm LO system is separate to prevent fuel oil contamination of the MLO system. Makeup to the Rocker Arm LO system is provided from the MLO system.
Purpose of starting air system.
Provides air for (1) Starting, (2) Control, and (3) Shutdown
Woodward Governor mechanical vs electrical.
Mechanical governor set higher than electrical. Electrical fails high and mechanical will take over.
Emergency start signal vs normal stop signal
On a normal stop signal with the engine still coasting down and emergency start signal will still start the diesel.
Emergency stop vs start PB.
On an emergency stop depressing the start PB will vent the air receivers to atmosphere.
How many starts does each air receiver tank capable of?
5
What must be done after a lockout?
The ENGINE RESET pushbutton must be pressed PRIOR to resetting the lockout.
