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Chapter 7
Troubleshooting
Table 30 - Metering
Symptom
Voltage does not read correctly
Current does not read correctly
172
Metering
If there is a difference between the metering data reported by the
CGCM-DLR unit and a reference meter, verify the metering that is used
to determine CGCM-DLR unit malfunction is being correctly used and
in calibration.
Most Likely Cause
Configuration errors
Wiring errors
Configuration errors
Wiring errors
Rockwell Automation Publication 1407-UM002B-EN-P - February 2019
Diagnostic Action
Observe VT configuration and
rotation parameters and to verify
that they reflect desired/expected
VT wiring
Observe each LL, phase, average
voltage, and rotation indication.
Indicated rotation matches
configured rotation. LL voltage (and
LN if applicable) indicated if all low
or high indicate ratio error, if one or
two are low or high indicate
polarity, grounding, or disconnection
Measure signal at CGCM-DLR unit
terminals
Observe CT configuration
parameters and to verify that they
reflect desired/ expected CT ratios
Observe each phase, and average
current indication. Each phase
current that is indicated is
approximately equal and the
average is the average of the three.
If all low or high indicate ratio error,
if one or two are low or high
indicate polarity, grounding, or
disconnection
Measure signal at CGCM-DLR unit
terminals
Corrective Action
Correct configuration to match
expected VT wiring
Correct phase rotation, polarity,
grounding, or fusing as applicable
If voltage indicated corresponds to
measured value, correct VT wiring.
If voltage indicated does not
correspond to measured voltage,
see configuration errors. If
configuration is correct, replace
CGCM-DLR unit
Correct configuration to match
expected CT wiring
Correct phase rotation, polarity, or
grounding, as applicable. Confirm
that the correct CT inputs are used
If current indicated corresponds to
measured value, correct CT wiring.
If current indicated does not
correspond to the measured current,
see configuration errors. If
configuration is correct, replace
CGCM-DLR unit
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