Allen-Bradley 1407-CGCM, User Manual, Page: 159 / 252

Rockwell Automation Publication 1407-UM001H-EN-P - November 2014
Troubleshooting #HAPTER
VARs do not share at all and when a
voltage adjust is made, reactive
power transfers to/ from the
machine Cross current mode is not
enabled/selected Check $ROOP?###4?3ELECT tag If not active, check/correct logic for
mode selection
Wiring error Measure voltage at ID+/- terminal
and adjust reactive power/voltage Correct wiring as required if voltage
signal from CCCT circuit is not
observed
Gain mis-adjustment Check CCCT Gain Correct as required
VARs transfer opposite from one
generator to another CT polarity or differential circuit
wiring error Verify CT polarity on each generator
by disconnecting differential circuit
and operating on cross-current
control Correct CT polarity and differential
circuit wiring as needed
VARs share but are unstable Gain mis-adjustment Check CCCT Gain Correct as required
4ABLE#OMPENSATION-ODES#ROSS#URRENT
3YMPTOM -OST,IKELY#AUSE $IAGNOSTIC!CTION #ORRECTIVE!CTION
4ABLE#OMPENSATION-ODES,INE$ROP
3YMPTOM -OST,IKELY#AUSE $IAGNOSTIC!CTION #ORRECTIVE!CTION
Voltage does not change with
changes in reactive load while not
connected to the grid Line Drop not active Check tag
,INE$ROP#OMP
If not active, check/correct logic for
mode selection
Metering error See Metering troubleshooting See Metering troubleshooting
Voltage is unstable AVR Gains misadjusted Check voltage stability when
operating isolated from load and if
possible in constant voltage control Calculate/correct AVR gains if
required
Metering error See Metering troubleshooting See Metering troubleshooting
4ABLE,IMITING-ODES5%,
3YMPTOM -OST,IKELY#AUSE $IAGNOSTIC!CTION #ORRECTIVE!CTION
VARs absorbed exceed the
programmed UEL limit (UEL does not
limit/activate) UEL not enabled Check tag 5%,?%N and
configuration
Correct logic or configuration as
required
UEL Gain misadjusted Force into UEL Adjust gains as required
UEL not configured Check UEL curve intercepts against
reactive capability curve Correct as required
Metering error See Metering troubleshooting See Metering troubleshooting
Excitation is unstable when UEL is
active UEL Gain misadjusted Force into UEL Adjust gains as required