Danfoss VLT AutomationDrive FC 303 Instruction Manual page 74

Basic Troubleshooting
Symptom
Phase to phase short
Motor overload
Open power fuses or circuit
breaker trip
Loose connections
Problem with line power (See
Alarm 4 Line phase loss
Line power current description)
imbalance greater than 3%
Problem with the Adjustable
frequency drive unit
Problem with motor or motor
wiring
Motor current imbalance
greater than 3%
Problem with drive unit
VLT ® AutomationDrive Instruction
Manual
Possible Cause
Motor or panel has a short phase
to phase. Check motor and panel
phase to phase for shorts.
Motor is overloaded for the
application.
Perform pre-startup check for loose
connections.
Rotate input power leads into the
drive one position: A to B, B to C, C
to A.
Rotate input power leads into the
Adjustable frequency drive one
position: A to B, B to C, C to A.
Rotate output motor leads one
position: U to V, V to W, W to U.
Rotate output motor leads one
position: U to V, V to W, W to U.
®
MG.33.AI.22 - VLT is a registered Danfoss trademark
Test
Eliminate any shorts detected.
Perform start-up test and verify
motor current is within specifi-
cations. If motor current is
exceeding nameplate full load
current, motor may run only with
reduced load. Review the specifi-
cations for the application.
Tighten loose connections.
If imbalanced leg follows the wire,
it is a power problem. Check line
power supply.
If imbalance leg stays on same
input terminal, it is a problem with
the unit. Contact supplier.
If imbalanced leg follows the wire,
the problem is in the motor or
motor wiring. Check motor and
motor wiring.
If imbalance leg stays on same
output terminal, it is a problem
with the unit. Contact supplier.
Solution
9
9-3
9