Manual

Rockwell Automation Publication 1407-UM001G-EN-P - April 2013 157
Troubleshooting Chapter 7
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 Droop_CCCT_Select 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
Table 24 - Compensation Modes - Cross Current
Symptom Most Likely Cause Diagnostic Action Corrective Action
Table 25 - Compensation Modes - Line Drop
Symptom Most Likely Cause Diagnostic Action Corrective Action
Voltage does not change with
changes in reactive load while not
connected to the grid
Line Drop not active Check tag LineDropComp 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
Table 26 - Limiting Modes - UEL
Symptom Most Likely Cause Diagnostic Action Corrective Action
VARs absorbed exceed the
programmed UEL limit (UEL does not
limit/activate)
UEL not enabled Check tag UEL_En 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