Diesel Generator/Diesel Fuel Oil (DG) Flashcards
How long does it take a DG to start and attain full-load speed and accept load on a cold start?
10 seconds
What is the rated output of the DG?
5500 KW continuous and 6050 KW for 2 of 24 hours
What signals automatically start the diesel generator?
SIAS
AFAS
LOP
CSAS (test mode unless SIAS also present)
WHat is rated speed and voltage of the DGs?
600 rpm
60 hz
4160 VAC
Why should operation of the DG above 4300 VAC be minimized?
prevent over voltage on downstream MCCs
Operating the Diesel Generator in parallel with offsite power, while picking up reactive load (+VARS), may cause increased voltage conditions PBA-S03/ PBB-S04.
What is the lower limit for operating load on the DGs?
25%
When the DG mode control switch is in ‘OFF’, what does that mean for operability?
inoperable
What are the DG emergency Trips?
Overspeed 660 RPM (ONLY Mechanical overspeed trip)
Generator Differential (current going in is different then what’s going out)
Low Lube Oil pressure (30 psig on 2/4)
How can the DG be stopped mechanically?
Butterfly Valve
Manuel Rack
○ Pull and HOLD
DG Fuel Oil Day Tank outlet valve
How long can the DG run without the SP pump running?
15 minutes unloaded
2.6 minutes loaded
What provides power to the ‘A’ DG control panel, control circuits and indication?
‘B’ DG?
NKN-D42
NKN-D43
On a loss of NK to the DG, what is affected?
What is still available?
Will the DG trip if running?
normal test run functions and control room indications
ability to emergency start/run the diesel (cant start from the control room)
No
What does Pk power for the DGs?
What happens to the DGs on a loss of PK?
Why is a loss of PK so detrimental if the DG is running and supplying power to the bus?
control circuits and provides field flashing power
loss of controls, starting circuit and electrical protection
If DG is running, DG trips and Output breaker fails as is
if paralleled to offsite power, DG will motorize
At what RPM does the DG trip on overspeed?
660 RPM (110%)
What does the overspeed governor isolate at the trip setpoint?
isolates fuel and combustion air
What is the only mechanical automatic trip available for tripping the DG on a loss of Control Air?
overspeed trip
What is the purpose of the Turbocharger on the DGs?
increase engine efficiency and fuel economy
How would the turning gear disable the DG from starting?
Two pneumatic Turning Gear Interlocks prevent cranking air from starting the engine when the turning gear is not fully disengaged
How much fuel does the DG use at full rated load?
6.55 gpm
What is the tech spec minimum level for the DG Fuel Oil Storage Tank?
How many days of run time does this give us?
> /= 80% (~71,383 gal)
7 days of continuous use at 100% rated output
Where are the DG Fuel Oil Transfer pumps powered from?
PH
What is the minimum Tech Spec level for the DG fuel Oil Day Tank?
What is the basis for this?
2.75’ (550 gal)
60 minute supply with 10% margin if DG is at full rated power
What are the makeup sources for DG jacket water?
Normal - DW
backup - CT
emergency - FP
What does DG jacket water supply cooling water to?
When does the DG become inoperable on JW temperature?
engine cylinder jackets
main governor
turbo
<105*F
What temperature is maintained for Jacket water when the engine driven pump is inservice?
165-175*F
modulated to maintain 170*F
When does the DG jacket water circ pump and heater cycle on and off?
On </= 120*F
OFF >/= 135*F
When does the Motor driven LO circ pump start and stop?
DG < 280 rpm ON
> 280 rpm OFF
When does the DG become inoperable on LO temperature?
< 105*F
What is the trip logic for the DG on Low Lube Oil Pressure?
Test Run
1/2 switches
‘A’ DG PSL3 or PSL5
‘B’ DG PSL4 or PSL6
Emergency Run
requires 2/4 to trip the DG
1/2, taken twice (Example: ‘A’ DG PSL3 or PSL5 AND PSL-7 or PSL-9)
What is the purpose of DG Control Air?
operate various controls on the DG engine
supplies Non-Fail-Safe air
On a loss of control air, how can the DG be tripped?
manual fuel rack, O/S butterfly valve, main governor Load Limit Control Knob to minimum fuel position
What does DG cranking air do?
air pressure applied to the tops of the pistons through the air distributer to start rolling (cranking) the DG
What is Non-Fail-Safe air in the DG starting Air system?
How is the DG affected on a loss of this?
supplies the ‘ON’ and ‘OFF’ air to the fuel control cylinder (bimba)
DG has to be tripped manually via butterfly valve or fuel rack
What are the 5 conditions that must be met in order to start the DG?
- Overspeed reset
- Generator differential reset
- Low engine lube oil pressure reset
- Emergency stop pushbutton in reset position
- Mode control switch not in “off” (remote or local)
Describe how the start signals are generated for starting the DG
DGSS (Diesel Generator Start System) starts the DG in test mode on receipt of SLAC
From PPS-ESFAS, Diesel will start in Emergency mode on SIAS/CSAS or AFAS
From BOP-ESFAS, DG will start in emergency mode on LOP
CSAS by itself will start in test mode
What are the required conditions for the DG to start?
Automatic closing
- LOP
- Diesel Generator at rated speed and voltage
- No faults (86 lockout) on the normal and alternate supply breakers
- both normal and alternate supply breakers OPEN
Manual closing
- Diesel generator at rated speed and voltage
- No fault on the normal or alternate supply breaker
- Alternate supply breaker open
- Sync key must be on
During an emergency run, what mode is the diesel started in (isoch or droop)?
What does this remove control of from the control room?
isoch
control of speed and voltage (take to override to get control back)
What three trips will stop the DG in emergency mode?
generator differential
overspeed
low lube oil pressure
If the DG was started due to a SIAS or AFAS, what should be done before securing the DG?
reset the ESFAS signals
If the DG is in its 5 minute cooldown period during an emergency run, what happens if a trip comes in?
cooldown is terminated and the DG trips
If a DG is supply the class bus, can the alternate supply breaker for that bus be closed in (paralleled)?
no
there is an interlock that prevents it. the DG would have to be emergency stopped and then the alt supply breaker can close
With the emergency mode interlock defeat switch in ‘ON’ in what mode will the DG start for a LOP?
SIAS?
AFAS?
test mode with all test trips enabled
emergency mode, until taken to override. then it will be out of emergency mode and all test trips enabled
emergency mode, until taken to override. then it will be out of emergency mode and all test trips enabled
If the DG started in Emergency mode, what happens when the CR handswitch is taken to OVERRIDE?
§ Speed control is re-established
§ Speed and voltage mode of control is selectable between “Isoch” and “Droop”
§ Voltage control is re-established
§ Three DG output breaker trips are re-established (Overcurrent, Neutral Voltage, Negative sequence).
§ Disables the DGSS hard start.
§ Bypass of the automatic trip of the output breaker if a SIAS, AFAS-1 or AFAS-2 signal was present. A LOP signal would still trip the output breaker.
§ The “Override” white light comes on in the control room on B01.
