EDG Flashcards
What is EDG rated output?
- Continuously rated for 2,500 KW at 80% power factor
- 2,750 KW, 2-hour rating.
- Output Breaker trips at 824 Amps. 752 ams is normal rating.
What Air Start System setpoints for operability and normal ranges?
- 100 rpm crank for 40 seconds with 90 psi to the starting air motor.
- Starting air is normally provided to the air start motors at 150 psig and tank pressure is greater than 235 psig.
- Tank pressure must be ≥215 psig per SOP-22 to be Operable
- Starting air >=95 psig but <= 175 psig per SOP-22 to be Operable
For the Lube Oil System, describe its operational design basis and the normal operating range.
- Provides lubrication for engine bearings, vibration damper, turbocharger, and internal crankcase components during engine operation.
- Maintains the engine at approximately 120°F for fast starting when shutdown.
- Normal operating temperature between 175°F and 190°F with max of 200°F.
- The system normal operating pressure is between 80 psig and 90 psig.
- System normal operating flow is approximately 320 gpm.
- Must be >90F and < 205F
For the Fuel Oil System, describe its operational design basis and the normal operating range.
Provides storage of an adequate fuel supply,
- 28,592 gallons is 6 day supply
The engine system normal operating pressure is between 40 psig and 60 psig.
For the Jacket Cooling Water System, describe its operational design basis and the normal operating range.
- Removes heat from the engine cylinders, block, heads, turbocharger, and aftercooler during operation, and maintains the engine at an elevated “Standby” temperature of approximately 120°F for fast starting when shutdown.
- Normal operating temperature is between 160°F and 185°F, maximum allowable is 195°F.
- The system normal operating pressure is between 10 psig and 50 psig.
- System normal operating flow is between 630 gpm and 700 gpm.
- The jacket water surge tank provides for jacket water expansion, makeup, inhibitor addition, and pump suction head. The tank also provides sufficient static head to protect the turbocharger from low water and vents air entrapped in the system
For the Turbocharger, describe its operational design basis and the normal operating range.
Uses hot exhaust gases to drive a turbine that takes in fresh air, compresses it (15 to 24 psig), and forces the air into the cylinders on the intake stroke. Exhaust temperatures (loaded) reach approximately 1200°F. To prevent heat damage to the turbocharger and to ensure cool air is discharged into the intake manifold, jacket water and lube oil are piped to the turbocharger. At full rated load and speed, the maximum allowable turbocharger inlet exhaust gas temperature is 1350°F
For the NSD/DBA Sequencers, describe its operational design basis and the normal operating range.
- There are two separate, independent load sequencing channels (left and right), each consisting of a load sequencer and its associated actuation logic located in in Control Room Panel C-13.
- The sequencers and their input logic are powered from separate, independent Preferred AC panels (Y20 and Y30).
- Each sequencer contains a processor, an AC input card, two AC output cards and three DC output cards.
- 55 seconds cycle time
What is the 1-1 EDG Output Breaker?
152-107
What is the 1-2 EDG Output Breaker?
152-213
What are the features of the Emergency Diesel Generator Output Breaker Interlocks for manual operations?
- The generator overcurrent/differential lockout relay is reset.
- No bus overcurrent lockout relay present.
- The breaker’s manual synchro-switch is closed.
- The synchro-check circuit senses generator output voltage and phase sufficiently close to that of the bus to provide the close permissive to the generator breaker
What are the features of the Emergency Diesel Generator Output Breaker Interlocks for automatic operations?
- Both incoming bus supply breakers (i.e., from both the Safeguard Bus 152-105 and SUT 1‑2 152-106) are open.
- The generator overcurrent/differential lockout relay is reset.
- No bus overcurrent lockout relay present.
- Adequate EDG output voltage (as determined by the “127D” voltage relays [3/3 logic]).
- Confirmed 2400 V AC bus load shed (3 and 4 together = 106-D1 relay made up) The confirmed load shed is necessary to assure that the bus is sufficiently clear to preclude excessive blockloading of the generator upon breaker closure.
What lockout protection is provided to the Emergency Diesel Generator output breakers?
Lockout protection is provided to preclude auto-closure of the EDG breaker to a faulted bus. The bus lockout protection initiates when the normal supply (Station Power/Safeguards) breaker trips on overcurrent. The EDG will automatically start on an undervoltage signal but the overcurrent trip will block the EDG breaker automatic closure until the overcurrent lockout relay has been manually reset.
What is the Woodward Governor mechanical subsystem for speed/load control for the Emergency Diesel Generator?
- It provides backup for the electrical governor during EDG operation.
- The mechanical governor limits fuel to the engine to maintain the speed at setpoint.
- The speed setpoint is maintained higher than the electronic governor setpoint.
- Speed droop is applied to the speed setpoint to ensure proper operation (stability) when the EDG is paralleled to the grid.
- A speed droop control knob located on the governor sets the speed droop input. If the EDG is operated in the isochronous (unit) mode, the speed droop must be set to zero to maintain frequency at 60Hz
What is the Woodward Governor electrical subsystem for speed/load control for the Emergency Diesel Generator?
- The electronic governor control system normally assumes control of the engine fuel supply after intial startup.
- It uses the electrical input section of the governor/actuator to control the generator output frequency in the unit mode or load in parallel mode.
- The Woodward EGA Controller is located at Panel C-22 (C-26).
- The electronic governor operates in the isochronous (unit) mode when the PARALLEL/UNIT selector switch is in the UNIT position and in the droop mode when in the PARALLEL position.
What is the Unit Control Mode of the Woodward Governor electrical subsystem for speed/load control for the Emergency Diesel Generator?
- Established by the unit/parallel switch in the UNIT position
- Used to control frequency during emergency operation when the generator operates independently from other 60Hz power sources.
- In Unit mode, load shed breaker interlocks assure that the generator can only be connected to a dead bus.
- Loading of the generator is “controlled” by the load shed system (which clears most loads from the bus automatically before generator connection), in conjunction with the DBA/NSD sequencer (which “controls” the maximum step loading and the total generator load automatically following connection to the bus).
What is the Parallel Control Mode of the Woodward Governor electrical subsystem for speed/load control for the Emergency Diesel Generator?
- Established by the unit/parallel switch in the PARALLEL position
- Used to control generator load during EDG load testing.
- EDG runs in parallel and follows frequency with station or offsite power sources (grid), which appear as an infinite bus to the EDG.
- When supplying power to the infinite bus (grid) during parallel operation, the emergency generator must be prevented from carrying too much real and reactive load due to fluctuations of grid frequency and voltage.
What is Speed Droop Control?
- To prevent excessive real loading and add stability to the control system, the electronic governor operates with speed droop while in the Parallel Control Mode.
- Speed droop is set internally in the EGA (electronic governor control).
- Speed droop automatically adjusts the speed setting to a preset value based upon generator output (load).
- To prevent excessive reactive loadings and add stability to the control system, the voltage regulator operates automatically with voltage droop while in the Parallel Control Mode.
(a) The voltage droop mode prevents the generator from carrying too much reactive load in the over-excited or under-excited mode with respect to the infinite bus (grid).
What are the EDG 187 Relays?
Three (187) differential relays (one per phase) are connected to current transformers, one set on the neutral side of the generator windings and the other set on the bus side of the 2400V EDG incoming circuit breaker.
This arrangement protects the generator, generator incoming circuit breaker and the power cables against faults in this zone.
The relays trip the 2400V EDG breaker via lockout relay (186) and shut down the diesel engine via the shutdown relay (SDR).
What are the EDG 151 Relays?
Three inverse time overcurrent relays (151) are connected on the generator side of the EDG 2400V breaker to protect the EDG circuit from overloads.
They function by tripping the EDG breaker via lockout relay (186) and shut down the diesel engine via the engine shutdown relay (SDR).
The relays provide an alarm at 100% of the generator nameplate loading and trip the generator at 110% of the nameplate rating, based on 3125 KVA at 80% power factor.
The overcurrent trip logic is a two out of three (2/3) coincidence.
Trip Setpoint is 824 amps.
What is Incomplete or Cranking Failure Start for the EDG?
- Activated by Overcrank Timer 1 or OCT2 or Overcrank Relay (OCR).
- Engine cranking for > 10 seconds with <= 10 psig Jacket Water Pressure and RPM < 120.
Describe the consequences of operating the Emergency Diesel Generators under improper temperature, pressure or flow parameters (water, air, oil)
If lube oil pressure <= 40 psig and EDG not tripped, then trip it.
If lube oil pressure DP > 20 psid, then EDG in operable. If conditions allow, shut down unit.
If lube oil temperature >= 200F with no service water, then trip it. Otherwise unload and secure if plant conditions permit. If less than 90F then EDG in operable.
If raw water pressure <= 25 psig and loss of service water, then trip the diesel. If operation required, maintain JW Temp <195F and Oil <205.
JW pressure less than 10 psig trips off crankcase exhausters and requries unit shut down if other power available.
If JW temperature >= 195 or <=95, then EDG in operable. If conditions permit, unload and stop.
If starting air pressure < 95 psig on two indicaters, EDG is inoperable.
Describe the consequences of operating the Emergency Diesel Generators in an under excited condition.
Excessive reactive load can result in generator high currents and over-heating. When the rotor field excitation is less than that required, leading reactive current flows in the generator stator windings. These flows in the generator stator winding can cause the stator end-turns can overheat, this leads to insulation damage. If left unchecked, the rotor field strength can weaken to the point that the generator could “slip a pole”. This causes catastrophic failure of the coupling between the prime mover and the generator, and sometimes worse
Describe the consequences of operating the Emergency Diesel Generators in an over excited condition.
Over excitation of a generator causes saturation of the magnetic core of the generator, and stray flux may be induced in non-laminated components that are not designed to carry flux. Excessive flux may also cause excessive eddy currents in the generator laminations that result in excessive voltages between laminations. This may cause severe overheating in the generator or transformer and eventual breakdown in insulation”
Describe the consequences of closing a breaker between buses with unmatched frequency or voltage.
Sync Check should not allow it. Generator/breaker damage is result.
Describe the consequences of operating the Emergency Diesel Generators with a Loss of Diesel Generator room cooling.
Generator/Exciter overheating. Both fans required if outside air temp 85F or greater.
Describe the consequences of operating the Emergency Diesel Generators with loss of bus control power, trip features.
EDG Damage, no start of EDG
Describe the consequences of operating the Emergency Diesel Generators with a loss of off-site power during full load testing of Diesel Generator in accordance with SOP-22, AOP-20/21, ARP-20.
Output breaker trips, place in Unit mode after EOP-1.0 actions completed.
What is the power supply to P-18A?
480V MCC-8. MCC-8 is powered via LCC-12 via D-Bus
What is the power supply to P-18B?
480V MCC-1 via LCC-19 and C-Bus
What is the power supply to C-3A, 1-1 EDG Air Compressor?
Electrical: 52-116C, via 52-116 via MCC-1 via LCC-19 via C-Bus
Gasoline engine.