Symptom
Possible cause
Test
Solution
Problem with the AC drive.
Rotate input power leads into the
AC drive 1 position: A to B, B to C, C
to A.
If the imbalanced leg stays on same in-
put terminal, it is a problem with the
AC drive. Contact the supplier.
Motor current
imbalance
greater than 3%
Problem with motor or motor
wiring.
Rotate output motor cables 1 posi-
tion: U to V, V to W, W to U.
If the imbalanced leg follows the wire,
the problem is in the motor or motor
wiring. Check motor and motor wiring.
Problem with AC drive.
Rotate output motor cables 1 posi-
tion: U to V, V to W, W to U.
If the imbalanced leg stays on same
output terminal, it is a problem with
the unit. Contact the supplier.
AC drive accel-
eration prob-
lems
Motor data are entered incor-
rectly.
If warnings or alarms occur, refer to
the
Warnings and Alarms
section.
Check that motor data are entered
correctly.
Increase the ramp-up time in
parame-
ter 3-41 Ramp 1 Ramp Up Time
. Increase
current limit in
parameter 4-18 Current
Limit
. Increase torque limit in
parame-
ter 4-16 Torque Limit Motor Mode
.
AC drive decel-
eration prob-
lems
Motor data are entered incor-
rectly.
If warnings or alarms occur, refer to
the
Warnings and Alarms
section.
Check that motor data are entered
correctly.
Increase the ramp-down time in
pa-
rameter 3-42 Ramp 1 Ramp Down Time
.
Enable overvoltage control in
parame-
ter 2-17 Over-voltage Control
.
AQ357954340588en-000201 / 130R0881
140 | Danfoss A/S © 2020.09
Maintenance, Diagnostics, and
Troubleshooting
VLT® Refrigeration Drive FC 103
Operating Guide
Summary of Contents for VLT FC 103
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