Danfoss MCD500 Service Manual page 8

Troubleshooting
Display
L1 Phase Loss
L2 Phase Loss
L3 Phase Loss
L1-T1 Shorted
L2-T2 Shorted
L3-T3 Shorted
Low Control Volts
Motor Overload/
Motor 2 Overlaod
Motor Connection
Motor Thermistor
Network Comms
Parameter out of Range
Phase Sequence
MCD 500 Service Manual
Possible cause/Suggested solution
During prestart checks the starter has detected a phase loss as indicated.
In run state, the starter has detected that the current on the affected phase has dropped below 3.3%
of the programmed motor FLC for more than 1 second, indicating that either the incoming phase or
connection to the motor has been lost.
Check the supply and the input and output connections at the starter and at the motor end.
Phase loss can also be caused by a failed SCR, particularly an SCR that has failed open circuit. A failed
SCR can only be definitely diagnosed by replacing the SCR and checking the starter's performance.
Related Pars.: None
During prestart checks the starter has detected a shorted SCR or a short within the bypass contactor
as indicated.
Related Pars.: none
The internal 24 VDC rail has dropped below 19V. This may have been caused by a fluctuation of the
control supply. Reset the trip. If the problem persists:
•
The 24 V supply in the main control PCB may be faulty; or
•
the bypass driver PCB may be faulty (internally bypassed models only).
These trips cannot be reset. Contact your local supplier for advice.
Related Pars: None
The motor has reached its maximum thermal capacity. Overload can be caused by:
- The soft starter protection settings not matching the motor thermal capacity.
- Excessive starts per hour
- Excessive throughput
- Damage to the motor windings.
Resolve the cause of the overload and allow the motor to cool.
Related Pars.: 1-1, 1-2, 1-3, 1-4, 7-1, 7-2, 7-3, 7-4, 16-1
The motor is not connected correctly to the soft starter for inline or inside delta use.
- Check individual motor connections to the soft starter for power circuit continuity.
- Check connections at the motor terminal box.
Related Pars.: 15-7
The motor thermistor input has been enabled and:
- The resistance at the thermistor input has exceeded 3.6 kΩ for more than one second.
- The motor winding has overheated. Identify the cause of the overheating and allow the motor to
cool before restarting.
- The motor thermistor input has been open.
NOTE
If a valid motor thermistor is no longer used, a 1.2 kΩ resistor must be fitted across
terminals 05, 06.
Related Pars.: 16-9
The network master has sent a trip command to the starter, or there may be a network communi-
cation problem.
Check the network for causes of communication inactivity.
Related Pars.: 16-11
- A parameter value is outside the valid range.
The starter will load the default value for all affected parameters. Press MAIN MENU to go to the first
invalid parameter and adjust the setting.
Related Pars.: None
The phase sequence on the soft starter's input terminals (L1, L2, L3) is not valid.
Check the phase sequence on L1, L2, L3 and ensure the setting in Par. 2-1 is suitable for the instal-
lation.
Related Pars.: 2-1
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MG.17.L4.02 - VLT is a registered Danfoss trademark
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