Danfoss VLT Alarm 13 Overcurrent

Alarm 13 Overcurrent in a Danfoss VLT Variable Frequency Drive (VFD) indicates that the output current has exceeded the drive's allowable protection limit. The drive continuously monitors the motor current to protect the inverter power module (IGBTs) and other internal components. When the output current rises above the trip threshold, the drive generates Alarm 13 and immediately stops the inverter output to prevent damage.

This alarm generally indicates a problem with the motor, motor cable, mechanical load, parameter settings, or inverter power stage, rather than the control circuitry.

Possible Causes

• Short circuit in the motor windings.
• Short circuit in the motor cable.
• Ground fault in the motor or motor cable.
• Incorrect motor wiring.
• Motor overload.
• Acceleration time too short.
• Sudden load changes.
• Mechanical jam or locked rotor.
• Motor bearing failure.
• Incorrect motor parameters.
• Incorrect V/f or motor control settings.
• Power factor correction capacitors connected to the drive output.
• Output contactor opened while the drive is running.
• Motor cable too long without an output filter or reactor.
• Defective IGBT power module.
• Internal drive hardware failure.

Solutions

1. Check the motor for winding faults or insulation failure.
2. Inspect the motor cable for damage, short circuits, or loose connections.
3. Verify that the motor wiring is correct.
4. Check for phase-to-phase and phase-to-ground faults using an insulation resistance tester, following the motor manufacturer's recommendations.
5. Inspect the driven machine for mechanical binding or overload.
6. Increase the acceleration time if it is too short.
7. Verify that the motor parameters match the motor nameplate.
8. Ensure the drive is correctly sized for the motor and application.
9. Remove any power factor correction capacitors connected to the drive output.
10. Do not switch an output contactor while the drive is running.
11. Install an output reactor or dV/dt filter if recommended for long motor cable runs.
12. If the fault persists with the motor disconnected, inspect the inverter output stage and replace defective components if necessary.

Additional Information

Danfoss VLT drives continuously monitor the inverter output current.

Alarm 13 Overcurrent is generated when the measured motor current exceeds the drive's protection threshold. The drive immediately disables the output to protect the:

• IGBT power module.
• DC bus capacitors.
• Rectifier section.
• Motor.

The most common causes are:

• Motor or cable short circuit.
• Mechanical overload.
• Incorrect acceleration settings.
• Incorrect motor parameter configuration.

Unlike an Overload Alarm, Alarm 13 Overcurrent is typically an instantaneous protection trip caused by a sudden excessive current.

Common Symptoms

• Drive displays Alarm 13 Overcurrent.
• Motor fails to start.
• Drive trips immediately after a RUN command.
• Fault occurs during rapid acceleration.
• Motor jerks before stopping.
• Drive trips during sudden load changes.
• High output current is displayed before the trip.
• Repeated trips after reset.
• Motor does not reach operating speed.
• In severe cases, damaged output components may prevent restart.

Recommended Troubleshooting Sequence

1. Verify that the alarm is Alarm 13 Overcurrent.
2. Disconnect power and follow lockout/tagout procedures.
3. Inspect the motor cable for damage.
4. Check motor terminal connections.
5. Measure motor insulation resistance according to the motor manufacturer's recommendations.
6. Verify motor winding resistance and phase balance.
7. Check the driven equipment for mechanical jamming.
8. Increase the acceleration time if required.
9. Verify motor parameter settings against the motor nameplate.
10. Ensure no power factor correction capacitors are connected to the drive output.
11. Disconnect the motor and test whether the drive still trips.
12. Inspect the inverter output stage if the alarm remains with the motor disconnected.
13. Repair or replace faulty components.
14. Restore power and perform a functional test.
15. Monitor the motor current during normal operation.

Danfoss VLT Alarm 13 Overcurrent Check Table

Check Point	Action
Motor	Check winding condition and insulation
Motor cable	Inspect for damage or short circuits
Ground fault	Test insulation to ground
Mechanical load	Remove jams or overload conditions
Acceleration time	Increase if too short
Motor parameters	Verify against the motor nameplate
Output contactor	Ensure it does not operate while the drive is running
Output reactor/filter	Install if required for long motor cables
Inverter output stage	Inspect if the alarm persists
Drive sizing	Verify correct drive selection

Preventive Maintenance Tips

• Inspect motor cables regularly for insulation damage.
• Test motor insulation resistance during scheduled maintenance.
• Keep motor terminals clean and tight.
• Use appropriate acceleration settings for the application.
• Do not install power factor correction capacitors on the drive output.
• Avoid switching output contactors while the drive is running.
• Install output reactors or dV/dt filters where recommended.
• Ensure adequate ventilation and cooling for the drive.
• Record recurring Alarm 13 Overcurrent events to identify developing mechanical or electrical problems.
• Follow Danfoss preventive maintenance recommendations.

Proper inspection of the motor, motor cable, mechanical load, motor parameters, acceleration settings, and inverter output stage will help prevent recurring Alarm 13 Overcurrent trips in Danfoss VLT drives, ensuring reliable motor control, effective inverter protection, and long-term system performance.