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Over-excitation Limiting (OEL) Operation
Perform this test with the generator operating unloaded in Constant Speed mode
and constant voltage AVR mode.
Follow these steps to test the OEL operation.
1. Enable the OEL function.
2. Determine the field current that is required to reach 105% of the rated
generator voltage.
3. Set the offline OEL high and low setpoints for a value equal to the field
current determined earlier.
4. Set the voltage setpoint to rated generator voltage.
5. Enable excitation.
6. Set the voltage setpoint to 110% of the rated output.
7. Verify that the generator maximum voltage remains at approximately
105% and that the OEL Active tag = 1.
8. Observe the response of the excitation current reported by the
CGCM-DLR unit.
9. Adjust the OEL gains as required to obtain the desired stable response.
10. Return the AVR setpoint to the rated output level.
11. Return the OEL settings to the values determined for the application.
Diode Monitor
Perform this test with the generator operating in any mode.
Follow these steps to test the Diode Monitor operation.
1. Input the number of main poles and exciter poles.
2. Determine the normal percent ripple by observing the ExcRipple tag value.
3. Find the highest percent ripple while operating the generator and prime
mover through the normal operating range.
4. Set the Open Diode Level to a value that is three times the highest normal
percent ripple that is found earlier.
The multiplier can be varied from 2...5 to adjust the trip margin. A
reduction of the multiplier can result in nuisance EDM open diode
indications.
Rockwell Automation Publication 1407-UM002B-EN-P - February 2019
CGCM-DLR Unit Startup
Chapter 5
137
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