Zach Stubby's Heavy Hitters - Electrical Systems Flashcards
(54 cards)
How does air receiver tank pressure affect EDG Emergency Start capability?
→Engine will rotate with air until > 200 rpm or pressure in both receivers < 150 lbs.
→Emergency start blocked if air receivers < 150 lbs.
(can still try normal start below 150 lbs)
What automatic protective features does EDG have after Emergency Start?
Automatic protective features are disabled except:
—>mechanical overspeed (115%)
—>generator differential (86-1 lockout).
How are full automatic protective features restored to EDG after Remote Manual Emergency Start?
→RLMS to LOCAL
→CR DG Emergency HS to STOP
→RLMS to REMOTE
What are the FO Storage Tank Tech Spec Minimum Volumes?
→Modes 1-6 for both
→FO Storage Tank Min volume 86,000 gal for 7 day supply
→FO Storage Tank Min Volume 74,600 gals for 6 day supply
Air Receiver Tank Pressure Limits
(both TS and Admin)
When does the low pressure alarm come in?
Tech Spec: ≥180 lbs
Admin: ≥184 lbs
Alarm: < 210 lbs
Day Tank Tech Spec Minimum Volume
1440 gal
(37” or 62%)
Note: EDG will actually run for ~2.8 hours based on 8-12 gpm fuel use
Which trips can’t be overridden with an emergency diesel start?
Phase to Phase Fault or Phase Differential (86-1)
Mechanical Overspeed (115%)
(must be manually reset at overspeed pivot lever)
When does the “Ready to Load” red light illuminate?
READY TO LOAD (red):
→engine speed ≥ 425 rpm
→generator output voltage ≥ 6210 VAC.
What are the limitations for running EDGs unloaded?
Minimize running the EDG unloaded
→ ≤ 5 minutes recommended
→ if operated for >30 mins unloaded, then machine must be loaded to remove any unburned fuel in the exhaust system
→when loaded, should run at minimum of 3.5 MW for 60 mins
If an EDG is connected to the grid during fluctuations…
…open the output breaker to prevent damage to the EDG.
EDG Response to Restart after Shutdown
→Normal: won’t restart in Normal for 2 minutes after shutdown
→Emergency: taking H/S to stop will stop EDG, but it will restart once < 200 rpm due to emergency start signal being locked in
Where is field flash powered from?
a train related DC bus
Which Tech Specs apply to the EDG system?
TS 3.8.1 - Requires OPT-215 when declaring an EDG inoperable (Modes 1-4)
TS 3.8.2 - one required offsite source and one required DG operable (Modes 5-6); if not met, check 6.9 kV and 480 VAC flashcard deck for actions
TS 3.8.3 - 7 day fuel oil and lube oil requirements, 48 hours to complete, if not met then declare EDG inoperable
TR 13.8.31 - AC Sources (Diesel Generator Requirements) - This TR LCO contains the surveillance requirements and associated actions for DG surveillances that are not absolutely necessary for EDG OPERABILITY, but still a good idea to be performed. It includes certain 18 month and 10 year TRS’s that send you to the applicable Tech Spec if not met.
What happens to the EDGs if they lose DC control power?
No field flash, no start signals. Won’t start on Normal or Emergency, locally or remotely.
If already running, can’t be stopped via handswitch. Must use local pneumatic trip button.
What are the Top 3 High Safety Significant Components?
→TDAFW Pump
→SSW
→EDG
If the EDG is tied to the bus for testing and an actual SI occurs, what is the EDG response?
→EDG will keep running unloaded
→EDG output breaker will open as long as normal or alternate feeder breaker is closed
How is the spare inverter supplied?
What can the spare inverter supply?
How does it provide this supply?
The spare inverter can be supplied from either train related DC bus or dirty power.
It can supply power to any of the 4 train related Instrument buses.
Through the appropriate inverters being replaced via removing from service a static transfer switch on the inverter itself.
When uEC1 and uEC2 are on Bypass power, their train related Blackout Sequencer is…
Inoperable
→on a loss of offsite power the sequencers will de-energize.
→also on a loss of power to these panels the EDG will trip if running normally and not start in auto or manual due to 86-2
→it will however start in Emergency Manual or SI.
What occurs on a loss of 2EC1 and 2EC2?
(Unit difference)
Unit 2 Only
Loss of 2EC1 or 2EC2 will result in:
→loss of Water Hammer interlocks, resulting in
→Feedwater Isolation, and requiring a
→Manual Reactor trip
(Unit 1 doesn’t have water hammer interlocks because of SG replacement)
Static Switch Auto Transfer Criteria
→DC input voltage ≤105 VDC
→AC output voltage drops to 50% normal value (~59 VAC)
→Output load current rises to 120% of rated value (~175 Amps)
AC Essential Lighting
(powered from 480 VAC via step down transformers)
Supplies lighting in areas essential to the safe shutdown of the plant (ECB, Aux Bldg, U1 and U2 SFGDs)
DC Emergency Lighting
Provided as a backup to AC lighting systems in locations where safety related functions are performed and for personnel safety in access and egress routes
In areas where the DC Emergency Lighting is provided, 8-hour rated battery packs or station batteries are provided
118 VAC Operability
→The individual distribution panels must be powered from an inverter which is supplied from a 125 VDC bus.
→When the swing inverter is used it must be supplied from the same DC bus as the inverter it is replacing.
→The off-going inverter must be removed from the DC bus prior to placing the swing inverter on the same DC bus.
Which breakers feed normal and alternate supplies to bus XA1?
What components does the XA1 bus carry?
XA1-2: normal
XA1-1: alternate
(backwards from normal)
XA1 carries vent chiller 5-9
