EHC Flashcards
State what the wobbulator does for the turbine
At 1500 RPM the turbine is unstable so the wobbulator
changes speed by 50RPM every 6 min 1450, 1500, 1550
State the speed that the TG switches to Auto Voltage Regulator mode
270 RPM
The exciter will auto start if the TG reaches 1710RPM
State precaution with using the Manual Raise lower buttons in the DCS
There is no confirmation box. Once you release the box the load setpoint is changed and ramp rate is 600%/HR (10%/min)
State the precaution with using the Remote Raise lower switch on the MCB
Make small adjustments to avoid excessive power transients.
This switch interfaces directly with the DEHC cabinets
increases load at 600%/HR
State how a turbine Runback affects the DCS
A Runback will adjust the load setpoint at the Runback rate.
The Load Limit will Track down with it staying 5% above the setpoint as long as Tracking is on.
State how a turbine Setback affects the DCS
A Setback will lower the Load limit at the Setback ramp rate. The Load Limiter tracking function is automatically turned off. The Load setpoint also changes to 2% above the Load Limit
State how the Load Limiter tracking function operates
The Load Limiter tracker will auto follow 5% above Load Actual
State the Turbine Runback signals
- Stator Cooling water high outlet temp 2/3 @
176F, 80C - Low Stator Inlet Pressure 2/3 @ 586 GPM (50#)
- Low Flow to High Volt Bushing 2/3 @ 47 GPM
- Stator inlet flow Low 2/3 @ 586 GPM
State Turbine Runback rate
Runback reduce load @ 30%/min
Runbacks to 22.1%
with a 15 second time delay to prevent spurious actions
State Turbine trip from Runback signals
After 2 minutes if armature current is not less than 25,000 amps then the turbine will trip
After 3.5 minutes if armature current is not less than 7,000 amps then the turbine will trip
State the Load Limit Ramp rates
Fast: 10%/second
Slow: 1%/second
