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Chapter 7
Troubleshooting
Table 34 - Protection
Symptom
Generator overvoltage (59)
Generator undervoltage (27)
Loss of sensing (60FL)
Loss of permanent magnet
generator (PMG/Excitation power)
(27)
Reverse VAR (40Q)
Over-frequency (81O)
Under-frequency (81U)
Reverse power (32R)
Rotating diode monitor
Phase rotation error (47)
Generator over-current (51)
176
Most Likely Cause
Rapid loss of large load
Gains mis-adjusted
Over load
Wiring error
Fuse open
Wiring error
Supply circuit breaker trip/fuse open
Wiring error
PMG failure
Incorrect configuration
Under-excitation
Incorrect operating mode selected
Governor error
Governor error
Governor error
Failed diode
Incorrect configuration
Insufficient number of fly back
diodes that are installed
Wiring error
Fault or large load condition
Incorrect configuration
Rockwell Automation Publication 1407-UM002B-EN-P - February 2019
Diagnostic Action
Check AVR gains
Check VT wiring. See Voltage
metering troubleshooting
Check VT fuses
Check for open connections and
phase rotation reversal
Check PMG supply. Measure with
voltmeter at CGCM-DLR unit PMG
input terminals
Check PMG supply. Measure with
voltmeter at CGCM-DLR unit PMG
input terminals
Check PMG supply. Measure with
voltmeter at CGCM-DLR unit PMG
input terminals
Check single-phase versus 3-phase
selection
Check UEL configuration if
necessary
Check selected operating mode for
operating requirements
Remove and test diodes
Confirm test / setup of diode
monitor parameters with active
parameters
Check number of external flyback
diodes that are installed at
CGCM-DLR excitation output if
necessary
See troubleshooting voltage
metering,
Table 30
Check configuration
Corrective Action
Calculate/adjust gains as required
Correct wiring as required
Replace as required
Correct wiring as required
Correct/replace PMG input
protection as required
Correct wiring as required
Repair as required
Correct as required
Correct as required
Select as appropriate
Correct as required
Correct as required
Correct as required
Replace diode
Correct as required
Install as required
Correct wiring as required
Correct as required
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