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Table 33 - Redundancy
Symptom
Both CGCM-DLR units operate as
primary (both provide excitation to
the generator)
One or both CGCM-DLR units do not
operate as primary
Table 34 - Protection
Symptom
Loss of excitation current (40)
Over-excitation voltage (59F)
Redundancy
Most Likely Cause
Serial cable is not properly
connected
Faulty wiring
Logix controller error
One CGCM-DLR unit has failed or is
not configured properly
Protection
Most Likely Cause
Wiring error
Gains mis-adjusted
Wiring error
Gains mis-adjusted
OEL limit exceeded
Rockwell Automation Publication 1407-UM002B-EN-P - February 2019
Diagnostic Action
Disable excitation to one
CGCM-DLR unit
Connect personal computer by using
hyperterminal or similar application
to verify communication output from
CGCM-DLR unit redundancy comm
port
Measure excitation enable input to
CGCM-DLR unit that does not act as
primary
Check operation of external relay
and associated wiring for
redundancy relay and output
Check wiring of excitation +/- output
from CGCM-DLR unit
Check output to excitation enable
input (hardware and software)
Check logic to redundancy relay (if
applicable)
Troubleshoot as nonredundant unit
Diagnostic Action
Check excitation output wiring
Check AVR gains
Check excitation output wiring
Check AVR gains
Check OEL operation
Troubleshooting
Chapter 7
Corrective Action
If excitation turns off as commanded
(one remaining unit operating),
repair / replace cable. If both units
continue to excite, replace
CGCM-DLR units
If communication exists, see
Communication. If no
communication output exists,
replace unit
Verify that voltage is applied to
excitation enable input terminal
Correct excitation redundancy relay
operation
Correct excitation output wiring
Correct logic as required
Correct logic as required
Correct or replace as needed
Corrective Action
Correct wiring as required
Calculate/adjust gains as required
Correct wiring as required
Calculate/adjust gains as required
Correct as required
175
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