Danfoss VLT MCD 600 Operating Manual page 139

Operating Guide | VLT® Soft Starter MCD 600
Symptom
The soft starter does
not respond to a start
command from either
the LCP or the digital
inputs.
Erratic and noisy mo-
tor operation
Remote LCP shows
Awaiting data
The soft starter does
not control the motor
correctly during start.
Motor does not reach
full speed.
Soft stop ends too
quickly.
After selecting adap-
tive control, the motor
used an ordinary start
and/or the second
start was different to
the first.
PowerThrough does
not operate when se-
lected
Parameter settings
cannot be stored.
Danfoss A/S © 2018.10
Probable cause/suggested solution
• The soft starter may be waiting for the restart delay to elapse. Parameter 5-16 Restart Delay controls
the length of the restart delay.
• The motor may be too hot to allow a start. The soft starter only allows a start when it calculates that
the motor has sufficient thermal capacity to complete the start successfully. Wait for the motor to
cool, before attempting another start.
• The reset input may be active. If the reset input is active, the soft starter does not operate.
• The soft starter may be waiting for control signals via the communications network (parameter 1-1
Command Source set to Network).
• The soft starter may be waiting for a scheduled auto-start (parameter 1-1 Command Source set to
Clock).
If the soft starter is connected to the motor using inside delta configuration, the soft starter may not be
detecting the connection correctly. Contact the local supplier for advice.
The LCP is not receiving data from the control PCB. Check the cable connection.
• Start performance may be unstable when using a low motor FLC setting (parameter 1-2 Motor Full
Load Current).
• Install power factor correction (PFC) capacitors on the supply side of the soft starter. Disconnect the
capacitors during starting and stopping. To control a dedicated PFC capacitor contactor, connect the
contactor to a programmable relay set to Run.
• High levels of harmonics on the mains supply side can affect the soft starter performance. If drives are
installed nearby, check that they are properly grounded and filtered.
• If the start current is too low, the motor does not produce enough torque to accelerate to full speed.
The soft starter may trip on excess start time.
Make sure that the motor starting parameters are appropriate for the application and that the in-
tended motor starting profile is used. If a programmable input is set to Motor Set Select, check that
the corresponding input is in the expected state.
• Check if the load is jammed. Check the load for severe overloading or a locked rotor situation.
• The soft stop settings may not be appropriate for the motor and load. Review the settings.
• If the motor is lightly loaded, soft stop has limited effect.
• The first adaptive control start is constant current so that the soft starter can learn from the motor
characteristics. Subsequent starts use adaptive control.
• The soft starter trips on Lx-Tx Shorted on the first start attempt after control power is applied. Power-
Through does not operate if control power is cycled between starts.
• Make sure to save the new value by pressing [Store] after adjusting a parameter setting. If pressing
[Back], the change is not saved. The soft starter does not show a confirmation.
• Check that parameter 10-7 Adjustment Lock is set to Read & Write. If the parameter is set to Read Only,
settings can be viewed but not changed.
N O T I C E
AQ262141844215en-000202 / 175R1174 | 139
Troubleshooting