Main Generator Excitation (EX2100e) Flashcards
What happens when an Silicon Controlled Rectifier fires?
EX2100e SCR’s fire ON to RAISE field excitation
What is the power supply for Excitation System Power Conversion Room?
Non Class IE 480 Volts, 3 Phase AC System (NG)
NGN-L08, NGN-L15 and NGN-L25
Non Class 125VDC System (NKN) - supplies 125VDC control power to the Excitation System from two separate non-class distribution panels NKN-D41and NKN-D44
120VAC Control Power - all 120VAC Power to the PCR is from the 480 VAC incoming feeds, stepped down from Control Power Transformers and distributed fromtwo separate lighting panels.
What does the Automatic Voltage Regulator (AVR) do in the EX2100e?
The** AVR** regulates generator terminal voltage.
The Field Voltage Regulator (FVR) is used in the Direct Control mode of operation (DC).
Therefore, we will refer to this regulator as the Manual Regulator
The manual regulator (FVR) regulates generator field voltage.
What happens on a loss of a EX2100e Bridge Cabinet Fans?
In the event of an individual fan malfunction, the lag fan will attempt to start. If neither fan starts then the specific power bridge will shut down and the redundant bridges will assume the additional load current necessary for the field. (have 4 power bridges, only need 3)
What happens when one EX2100e AC Cabinet Fan fails?
There are two of AC cabinet fans. These two fans are unlike the previously discussed BridgeCabinet Fans in that they both run continuously whenever the Exciter is in service. If one fan fails
the other can support continued Exciter operation. However, if both fans fail, the Exciter will tripcausing a Turbine/Generator Trip.
What fire protection system is used for the EX2100e?
o Detection (VESDA)
Alarm in MCR (Exciter trouble alarm AND on fire panel in SSR room)
o Suppression (STAT-X)
Manually activated from two local pull stations. Pull one to actuate.
Shuts down the PCR HVAC. Will lead to Exciter shutdown on high temperature within several minutes.
What does the Automatic Voltage Regulator control?
- Controls the FVR.
Error signal is is sent to the manual regulator (FVR)
o FVR (manual/DC regulator) controls the firing command to the power bridges.
What does the Manual Voltage Regulator control?
DC Regulator (Manual Voltage Regulator)
* Field Voltage Regulator (FVR) is used in the Direct Control (DC) mode of operation.
* Regulates generator field voltage.
* Controls firing sequence of the bridge.
* Feedback is the DC Bridge output voltage.
What does the Volts/Hertz Limiter protect against?
Voltage too high for a given frequency (causes excess current – heat damage, most limiting components are main transformers)
(limiters provide input to the AVR, automatic voltage regulator)
What does the Under Excitation Limiter (UEL) protect against?
o Prevents AVR from reducing excitation to a level which would cause stator end iron heating and/or keeps the generator from operating in a region that would be unstable if transferred to manual mode.
o Poll slippage
What is the purpose of the P-Bar alarm?
Ground detection
Define power factor
ratio of the true power flowing in a circuit to the apparent power in
the circuit.
pf = Pr/Pa
