Danfoss VLT FC 322 Instruction Manual page 68

Basic Troubleshooting VLT® Automation VT Drive FC 322 D-Frame Instruction Manual
Symptom Possible Cause
Phase to phase short
Motor overload
Open power fuses or circuit
breaker trip
Loose connections
Problem with mains power (See
Alarm 4 Mains phase loss
Mains current imbalance description)
greater than 3%
Problem with the frequency
converter
Problem with motor or motor
wiring
Motor current imbalance
greater than 3%
Problem with the frequency
converters
Acoustic noise or vibration
(e.g. a fan blade is making Resonances, e.g. in the motor/fan
noise or vibrations at system
certain frequencies)
Table 9.1
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Test Solution
Motor or panel has a short phase Eliminate any shorts detected.
to phase. Check motor and panel
phase for shorts.
Motor is overloaded for the Perform startup test and verify
application. 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.
Perform pre-startup check for loose Tighten loose connections.
connections.
Rotate input power leads into the If imbalanced leg follows the wire,
frequency converter one position: A it is a power problem. Check mains
to B, B to C, C to A. power supply.
Rotate input power leads into the If imbalance leg stays on same
frequency converter one position: A input terminal, it is a problem with
to B, B to C, C to A. the unit. Contact the supplier.
Rotate output motor leads one If imbalanced leg follows the wire,
position: U to V, V to W, W to U. the problem is in the motor or
motor wiring. Check motor and
motor wiring.
Rotate output motor leads one If imbalance leg stays on same
position: U to V, V to W, W to U. output terminal, it is a problem
with the unit. Contact the supplier.
Bypass critical frequencies by using
parameters in parameter group
4-6*.
Turn off over-modulation in
Check if noise and/or vibration
14-03 Overmodulation.
have been reduced to an
Change switching pattern and
acceptable limit.
frequency in parameter group
14-0*.
Increase Resonance Dampening in
1-64 Resonance Dampening.
9 9
9-3