Danfoss mcd-500 Operating Instruction page 84

9 Troubleshooting
Display
Heatsink Overtemp
Input A Trip
Inst Overcurrent
Internal Fault X
L1 Phase Loss
L2 Phase Loss
L3 Phase Loss
L1-T1 Shorted
L2-T2 Shorted
L3-T3 Shorted
9 Low Control Volts
Motor Overload/
Motor 2 Overlaod
Motor Connection
Motor Thermistor
Network Comms
84
Possible cause/Suggested solution
Check if cooling fans are operating. If mounted in an enclosure check if ventilation is adequate.
On models with internal bypass, the cooling fans will operate:
- During the Start sequence and for 10 minutes after transition to Run.
- For 10 minutes after Stop.
Models without internal bypass will operate the cooling fans from a Start until 10 minutes after a Stop.
Related Pars.: 16-6
Identify and resolve the condition which caused Input A to activate.
Related Pars.: 3-3, 3-4, 3-5, 3-6, 3-7, 16-8
The motor has experienced a sharp rise in motor current, probably caused by a locked rotor condition
(shearpin) while running. This may indicate a jammed load.
Related Pars.: 2-6, 2-7, 16-4
The MCD 500 has tripped on an internal fault. Contact your local supplier with the fault code (X).
Related Pars.: None
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 connec-
tion 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 communication
problem.
Check the network for causes of communication inactivity.
Related Pars.: 16-11
MG.17.K2.02 - VLT ® is a registered Danfoss trademark
MCD 500 Operating Instruction