Danfoss VLT FC 103 Operating Instructions Manual page 68

Basic Troubleshooting
S S ymptom
Motor running in wrong
direction
Motor is not reaching
maximum speed
Motor speed unstable
Motor runs rough
9 9
Motor will not brake
Open power fuses or circuit
breaker trip
Mains current imbalance
greater than 3%
Motor current imbalance
greater than 3%
64
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Possible cause
Motor rotation limit
Active reversing signal
Wrong motor phase connection
Frequency limits set wrong
Reference input signal not scaled
correctly
Possible incorrect parameter
settings
Possible over-magnetization
Possible incorrect settings in the
brake parameters. Possible too
short ramp down times
Phase to phase short
Motor overload
Loose connections
Problem with mains power (See
Alarm 4 Mains phase loss
description)
Problem with the frequency
converter
Problem with motor or motor
wiring
Problem with the frequency
converters
MG16J102 - VLT is a registered Danfoss trademark
Test
Check that 4-10 Motor Speed
Direction is programmed correctly.
Check if a reversing command is
programmed for the terminal in
parameter group 5-1* Digital
inputs..
Check output limits in 4-13 Motor
Speed High Limit [RPM], 4-14 Motor
Speed High Limit [Hz] and 4-19 Max
Output Frequency.
Check reference input signal
scaling in 6-0* Analog I/O Mode and
parameter group 3-1* References.
Reference limits in parameter
group 3-0* Reference Limit.
Check the settings of all motor
parameters, including all motor
compensation settings. For closed
loop operation, check PID settings.
Check for incorrect motor settings
in all motor parameters
Check brake parameters. Check
ramp time settings
Motor or panel has a short phase
to phase. Check motor and panel
phase for shorts
Motor is overloaded for the
application
Perform pre-startup check for loose
connections
Rotate input power leads into the
frequency converter one position: A
to B, B to C, C to A.
Rotate input power leads into the
frequency converter 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.
Solution
Program correct settings
Deactivate reversing signal
See 2.4.5 Motor Rotation Check in
this manual
Program correct limits
Program correct settings
Check settings in parameter group
1-6* Analog I/O mode. For closed
loop operation, check settings in
parameter group 20-0* Feedback..
Check motor settings in parameter
groups 1-2* Motor Data, 1-3* Adv
Motor Data, and 1-5* Load Indep.
Setting.
Check parameter group 2-0* DC
Brake and 3-0* Reference Limits.
Eliminate any shorts detected
Perform startup 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 mains
power supply.
If imbalance leg stays on same
input terminal, it is a problem with
the unit. Contact the 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 the supplier.