DG/PE- Diesel Generators Flashcards
Top dead center (TDC)
When the piston is farthest from the crank shaft as possible
Bottom dead center (BDC)
When the piston is closest to the crank shaft as possible
Swept volume (cylinder displacement)
Volume swept out in the cylinder between BDC and TDC
Equals the product of piston stroke and it’s cross sectional area.
Clearance volume
The amount of space remaining in the cylinder when the piston is at TDC
How crank shaft position is measured
Degrees of rotation before (BTDC) or after top dead center (ATDC)
Engine displacement
The product of the cylinder displacement times the number of cylinders.
what is the purpose of the DG/PE system?
to supply 4160vac to reactor safety related loads
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
Which automatic start signal for DG provides power to the class busses? What do the other three do?
LOP
SIAS and AFAS go to no load, emergency standby mode
CSAS goes to non-emergency(droop) mode unloaded
What is the steady state unloaded voltage of the DG system?
4000-4377 actual
How long does a diesel generator have to be able to support a unit post accident?
7 days
What is the maximum leak rate through the diesel fuel cross connect valves? How long do you have to isolate instrument tubing after leakage initiation?
1.4 GPM
(168 gallons per train)
2 hours to isolate tubing
How does the DG/PE system interface with the DF system?
DF provides on-site storage of fuel oil for at least 7 days of operation
What is DF the system designator for?
diesel fuel oil and transfer system
How does the DG/PE system interface with the PK system?
DC power feed #2, starting circuit, engine panel, low voltage control panels, field flashing power
How does the DG/PE system interface with the NK system?
DG low voltage panel, instrumentation and alarms
How does the DG/PE system interface with the BOP ESFAS Sequencer (SA) system?
.DGSS contact in the BOP ESFAS originates from the module, contact closes on LOP, AFAS, SIAS or CSAS to start diesel in emergency mode.
What is required for the DG when there is a loss of the BOP ESFAS sequencer?
manual sequencing
How does the DG/PE system interface with the SP system?
provides cooling for jacket water, lube oil and intercooler heat exchangers
When the SP system is lost, How long do you have to secure the DG?
15 minutes unloaded
2.6 minutes loaded
How does the DG/PE system interface with the DW system?
DW provides make up water to the DG cooling water system(powered from NH)
What is the maximum leakage rate for jacket water?
1.6 gallon per hour
What system is CT the designator for?
condensate transfer
How does the DG/PE system interface with the CT system?
provides make up water to the Dg cooling water system (powered from PH)
How does the DG/PE system interface with the fire protection system?
provides a back up supply for make up water to the DG cooling water system when CT pumps and DW fail
What are the performance specs on the DG’s?
20 cylinder V-type turbocharger engine
drives a 5.5 MW generator
7670 HP for continuous output, 8437 HP for short time output
What drives the governors and camshaft?
Sprocket on the aft end of the camshaft
what drives the oil, fuel and water pumps at the forward end of the engine?
link driven sprocket and hub
Where, on the engine, is the turbocharger located?
the front
how is supercharging provided?
exhaust driven turbocharger
What cools the combustion air after being heated in the turbocharger?
the intercooler
What is the purpose of the crankshaft?
converts reciprocating motion of the pistons to rotational motion
What is the purpose of the pistons and connecting rods?
connecting rods connect the pistons to the crankshaft
internal combustion provides the reciprocating motion to the pistons
What is the purpose of the cylinder head and liner?
contains the inlet and exhaust valves and their operating mechanism, an air start valve and a fuel injector
What types of bearings are in the engine and what are the purposes of the bearings?
main bearings- support the crankshaft and provide the surface that the shaft rotates on
thrust bearings- limit crankshaft end play
connecting rod bearings- support the connecting rods
outboard bearings- support the generator
What is the purpose of the camshaft?
operate the fuel injection pumps, intake and exhaust valves
What is the purpose of the intake and exhaust valves?
intake valves-admit fuel and air into the cylinders
exhaust valves- discharge exhaust gases
What is the purpose of the turbocharger?
increases diesel efficiency by increasing air intake and exhaust
What is the purpose of the turning gear?
rotating the engine internals for maintenance
mounted on a rail at the engine flywheel
two pneumatic interlocks prevent engine start when turning gear not fully disengaged
What is the capacity of the fuel oil storage tank
84,000 gallons (7 days worth of 100% power operation plus 15%)
Where are the Fuel oil storage tanks located?
underground, below the frost line
How is water removed from the fuel oil storage tanks?
portable pump can draw off the bottom of the tank
What is the purpose of the fuel oil transfer pumps and where are they powered from?
they supply the fuel oil day tanks and are powered from PHA-M31 and PHB-M32
On the fuel oil transfer pumps, what traps suspended contaminants?
an integral filter on the pump discharge
How many fuel oil transfer pumps are there and what is their pumping rate?
one per diesel generator and twice the consumption of a diesel at full power
Describe the diesel fuel oil basket strainers.
located on the transfer pump discharge line, twin strainers, has a manual bypass, alarm at 2.5 psid
What is the capacity of the fuel oil day tanks? What is the tech spec minimum?
1100 gallons
2.75’ or 550 gal
How long can a diesel run on the fuel in the day tank?
1.9 hours fully loaded at the point when the fuel oil transfer pump kicks on
design requirement is 60 minutes fully loaded
what components does the fuel oil supply sub-system contain?
duplex fuel strainer duplex fuel filter engine-driven booster pump engine head tank fuel drains fuel injection system
What is the purpose of the fuel oil supply system?
to deliver fuel oil from the day tank to the high pressure fuel sub-system
What is the purpose of the high pressure fuel sub-system?
delivers fuel to the cylinders per governor demand and cam shaft rotation
What is the purpose of the injection pump?
supply high pressure fuel to the fuel injector
How does the fuel injector deliver the fuel into the cylinder head?
spray holes in the tip atomize the fuel into a fine mist and spray into the cylinder on the compression stroke
What separates the two trains of the fuel oil transfer pumps?
two locked closed valves
What is the purpose of the jacket water system?
cools the cylinder jackets, governor and turbocharger
What cools the jacket water cooler?
Essential spray pond water
When does the jacket water circulation pump and heater cycle on and off?
turns on at 120* decreasing and turns off at 135* increasing
what protection is provided for the jacket water heater if the level is low in the system?
none
What is the purpose of the jacket water thermostatic valve?
directs water to or bypasses the jacket water cooler
What temperatures determine the flow through the thermostatic valve in the jacket water system?
175* or greater, all flow to the cooler
170* partial flow in both directions
165* or less, all flow bypasses the cooler
What components does the air intake system consist of?
filter, silencer, over-speed shutdown butterfly valve heater/intercoolers
What is the purpose of the DG air intake filter and silencer?
cleans intake air and reduce noise
Where is the over-speed shutdown butterfly valve located?
turbocharger inlet piping
At what RPM will the over-speed governor trip the shutdown butterfly valve?
660 RPM
The shutdown butterfly valve is the only direct mechanical trip that will trip the DG on a loss of control air. How do you reset the valve?
pull the butterfly handle until it latches and then reset the OS (over-speed) governor
In the jacket water system, at what air temperature in the turbo compressor outlet will water run through a small heater core to maintain warm combustion air in the intake manifold?
105*F
What drives the DG turbocharger?
hot exhaust gases from each cylinder being directed through the turbine section of the turbo
What temperature do the essential exhaust fans keep the diesel room? When do they run?
50-122*F
When the diesels are running and after they shutdown until the room cools off
What is the purpose of the essential AHU for the diesel building?
maintain the DG control room at acceptable temperatures
When do the DG building essential HVAC units start?
ESFAS load sequencer starts the HVAC 25 seconds after DG reaches rated voltage and speed
What is the DG control equipment room essential AHU slaved to? At what room temperature will they shutdown after the DG is shutdown?
The DG room essential exhaust fan
110*
At what room temp. does the DG room ‘A’ heater turn on?
55*F
What are the DG room temp. limits per the UFSAR?
50-140*
At what temp. in the diesel control room does the normal AHU turn on?
105*
How can the DG’s be started?
pressing the local start button, manual switch in the unit control room, or upon the receipt of an emergency start signal
Manual speed and voltage control will not normally function in emergency mode. What will override this feature?
Overriding system from the control room
When needing to rotate the engine, what must be moved into position to engage the fly wheel?
the turning gear
what is able to lock the fly wheel in place while engine is at rest?
the turning gear
What controls the turning gear motor?
a three way valve
what prevents cranking air from starting when the turning gear is not fully disengaged?
two pneumatic interlocks
What drives the main governor? What controls it?
left camshaft
auto speed controller
What RPM is does the speed controller allow the DG run at while in manual mode?
608 RPM
Upon a start signal, fuel racks stay in the full open position until what RPM?
600
What drives the over speed governor?
right camshaft
How is the over speed governor powered? How is it lubricated?
self contained hydraulic system
engine oil
At what RPM does the over speed governor trip?
660
How does the over speed governor trip the diesel generator?
applies off air to fuel cylinder and trips butterfly valve
What allows the diesel output breaker to auto close?
LOP
DG rated speed and volts
no faults on normal or alternate breaker
both normal and alternate supply breakers open
What allows the DG output breaker to manually close from the control room?
DG at rated speed and volts
no faults on normal or alternate breakers
alternate breaker open
What allows the DG output breaker to manually close locally?
there are no requirements
What keeps the fuel control cylinder compressed, allowing the governor to control the fuel rack?
“on” air
How are the fuel shut off valve and air inlet butterfly valve reset?
manually
When are the low engine oil pressure switches bypassed?
for 20 seconds during start up and during shutdown when RPMs are below 570
Where are the low engine oil pressure switches located?
engine lube oil header
What is generator differential?
when the current going into a winding is not equal to the current leaving that winding
indicates that the generator windings have failed
When is droop mode used on the DG?
when the DG is paralleled with another source of power
when a CSAS is received
What is droop mode?
when the DG is paralleled to the grid, governor responds to load by lowering speed
in droop mode, what does the voltage regulator do?
lower voltage set point as a response to load
what is isochronous mode?
when the DG will run at a constant frequency and voltage as load changes
How long is the cool down cycle during a normal stop and what does it test?
5 minutes and it tests the two emergency run solenoids and pneumatic trip circuits
How is the diesel stopped during an emergency run?
override from the control room
What is the effect of losing control power to the diesel generator?
it will cause the DG to trip and lose capability of tripping the output breaker
loss of on class control power will prevent the control room starting the DG, not locally
what is the effect on the DG if control air is lost?
during start up, no effect
during shut down, unable to cut off fuel to diesel through fuel control cylinder
During an emergency run and a loss of control air, what do the emergency run trips actually trip?
output breaker
Per tech specs, how many starts are the air receivers required to be able to supply to the diesel without being recharged?
5
Per tech spec, how many days of full load power worth of lube oil and fuel oil is required to have on site per diesel generator?
7 days of both
What is the normal air pressure of the DG air receivers?
250 psi
What is the low alarm pressure of the starting air system? When does the pressure relief open?
185 psi
265 psi
How long do you have to re-pressurize the starting air receivers if they drop below 230 psi?
48 hours
What cools the air compressors?
fin tubed air cooled intercoolers between each compressor stage and an after cooler downstream of the 3rd stage with a fan blowing across them
what does the unloader valve do on the air compressors?
releases pressure during compressor start up to reduce starting current
on the air compressors, what does the condensate drain valve do?
removes condensation from the compressors and unloads 3rd stage of compressor
Why is there refrigerant in the air dryers?
to reduce the dew point of the air, helps to remove condensation
How many individual starting air systems are there and are they interconnected or completely independent from each other?
two
they are interconnected for the case of failures in either system
In the starting air system, what happens when the manual shut off valve at the outlet of each air receiver is not in its normal, full open position?
alarm at the local panel
From the starting air pressure of 250 psi, what pressure is the control air system regulated down to?
80 psi
In the starting air system, there are high pressure air supply lines ran to each cylinder bank. What is installed to warn operator of insufficient air to start the diesel?
air pressure sensors
What is the purpose of the starting air control valves?
the control valves admit starting air to the starting air distributor and valves
How many starting air solenoids are there? What do they do?
4-2 per cylinder bank
direct control air to the starting air control valves
What is the purpose of the starting air distributor?
its a timing device which operates the starting air valves on each cylinder by starting and stopping air flow in reference to the firing order of the engine
there is a small quantity of air piped from the turbo discharge to each start air header, what is this used for?
during DG operation, it continuously purges the starting air system and prevents moisture build up
How much pressure is applied to the turning gear to rotate the engine?
100 PSI
what prevents DG start failure in the case that one of the starting air valves fails to open
the starting air headers being cross connected
What does starting reset air do?
resets the pneumatic control circuit and locks out certain trips during start up
When does starting reset air get isolated?
when the DG is >280 rpm
