Allen-Bradley 1407-CGCM-DLR User Manual page 169

Table 24 - Compensation Modes - Cross Current
Symptom
VARs do not share at all and when a
voltage adjust is made, reactive
power transfers to/ from the
machine
VARs transfer opposite from one
generator to another
VARs share but are unstable
Table 25 - Compensation Modes - Line Drop
Symptom
Voltage does not change with
changes in reactive load while not
connected to the grid
Voltage is unstable
Table 26 - Limiting Modes - UEL
Symptom
VARs absorbed exceed the
programmed UEL limit (UEL does not
limit/activate)
Excitation is unstable when UEL is
active
Most Likely Cause
Cross current mode is not
enabled/selected
Wiring error
Gain mis-adjustment
CT polarity or differential circuit
wiring error
Gain mis-adjustment
Most Likely Cause
Line Drop not active
Metering error
AVR Gains misadjusted
Metering error
Most Likely Cause
UEL not enabled
UEL Gain misadjusted
UEL not configured
Metering error
UEL Gain misadjusted
Rockwell Automation Publication 1407-UM002B-EN-P - February 2019
Diagnostic Action
Check Droop_CCCT_Select tag
Measure voltage at ID+/- terminal
and adjust reactive power/voltage
Check CCCT Gain
Verify CT polarity on each generator
by disconnecting differential circuit
and operating on cross-current
control
Check CCCT Gain
Diagnostic Action
Check tag LineDropComp
See Metering troubleshooting
Table 30
Check voltage stability when
operating isolated from load and if
possible in constant voltage control
See Metering troubleshooting
Table 30
Diagnostic Action
Check tag UEL_En and
configuration
Force into UEL
Check UEL curve intercepts against
reactive capability curve
See Metering troubleshooting
Table 30
Force into UEL
Troubleshooting Chapter 7
Corrective Action
If not active, check/correct logic for
mode selection
Correct wiring as required if voltage
signal from CCCT circuit is not
observed
Correct as required
Correct CT polarity and differential
circuit wiring as needed
Correct as required
Corrective Action
If not active, check/correct logic for
mode selection
See Metering troubleshooting
Table 30
Calculate/correct AVR gains if
necessary
See Metering troubleshooting
Table 30
Corrective Action
Correct logic or configuration as
required
Adjust gains as required
Correct as required
See Metering troubleshooting
Table 30
Adjust gains as required
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