•
•
•
Symptom
Possible cause
Test
Solution
Terminal connection correct?
Scaling of terminals correct?
Reference signal available?
Motor running
in wrong direc-
tion
Motor rotation limit.
Check that
parameter 4-10 Motor
Speed Direction
is programmed cor-
rectly.
Program correct settings.
Active reversing signal.
Check if a reversing command is
programmed for the terminal in
pa-
rameter group 5-1* Digital inputs
.
Deactivate reversing signal.
Wrong motor phase connec-
tion.
–
Correct motor phase connection, or set
parameter 1-06 Clockwise Direction
to
[1] Inverse
.
Motor is not
reaching maxi-
mum speed
Frequency limits set wrong.
Check output limits in
parameter
4-13 Motor Speed High Limit [RPM]
,
parameter 4-14 Motor Speed High
Limit [Hz]
, and
parameter 4-19 Max
Output Frequency
.
Program correct limits.
Reference input signal not
scaled correctly.
Check reference input signal scal-
ing in
parameter group 6-0* Analog
I/O mode
and
parameter group 3-1*
References
.
Program correct settings.
Motor speed
unstable
Possible incorrect parameter
settings.
Check the settings of all motor pa-
rameters, including all motor com-
pensation settings. For closed-loop
operation, check PID settings.
Check settings in
parameter group 1-6*
Load Depen. Setting
. For closed-loop
operation, check settings in
parameter
group 20-0* Feedback
.
Motor runs
rough
Possible overmagnetization.
Check for incorrect motor settings
in all motor parameters.
Check motor settings in
parameter
groups 1-2* Motor data
,
1-3* Adv Motor
Data
, and
1-5* Load Indep. Setting
.
Motor does not
brake
Possible incorrect settings in
the brake parameters. Ramp-
down times may be too short.
Check brake parameters. Check
ramp time settings.
Check
parameter groups 2-0* DC Brake
and
3-0* Reference Limits
.
Open power
fuses
Phase-to-phase short.
Motor or panel has a short phase-
to-phase. Check motor and panel
phases for shorts.
Eliminate any shorts detected.
Motor overload.
Motor is overloaded for the appli-
cation.
Perform start-up test and verify that
motor current is within specifications.
If motor current is exceeding the
nameplate full load current, the motor
can run only with reduced load. Re-
view the specifications for the applica-
tion.
Loose connections.
Perform pre-start-up check for
loose connections.
Tighten loose connections.
Mains current
imbalance
greater than 3%
Problem with mains power
(see
Alarm 4, Mains phase loss
description).
Rotate input power leads into the
AC drive 1 position: A to B, B to C, C
to A.
If imbalanced leg follows the wire, it is
a power problem. Check the mains
supply.
AQ357954340588en-000201 / 130R0881 | 139
Danfoss A/S © 2020.09
Maintenance, Diagnostics, and
Troubleshooting
VLT® Refrigeration Drive FC 103
Operating Guide
