In this guide
A drive that trips is protecting itself, the motor or the process. Resetting it without reading the fault code just waits for the next trip. Here are the usual suspects and the first things to check.
Isolate and lock out before opening any panel or touching drive terminals. DC bus capacitors stay charged after power is removed. Only qualified people should work on drives.
Before you do anything else
- Record the fault code and, if the drive keeps one, the fault history and the values at the time of the trip
- Note what the machine was doing: starting, accelerating, running or stopping
- Note whether it happens at the same point every time
Overcurrent
The motor drew more current than the drive allows. Common causes:
- Acceleration ramp too short for the load
- A mechanical jam or a seized bearing or gearbox
- A short circuit or damaged motor cable or windings
- Wrong motor data entered in the drive
If it trips immediately on a start command, disconnect the motor and see whether the drive runs without a load. If it does, suspect the motor or cable.
Overvoltage
Usually seen when slowing down. A motor slowing a high-inertia load feeds energy back into the drive's DC bus and the voltage rises. Lengthen the deceleration ramp, add a braking resistor, or use a regenerative drive. Supply surges can also cause it.
Undervoltage and phase loss
The supply dipped or a phase dropped out. Check incoming fuses, contactors and terminals, and measure the supply under load. Where outages are common, see our guide on load shedding and control systems.
Overtemperature
The drive or its heatsink got too hot. Check:
- The cooling fan and the airflow path, including filters and dust-clogged heatsinks
- Panel ambient temperature and ventilation
- Switching frequency, since a high setting adds heat
- Altitude or temperature derating, which can lower what the drive can deliver on the Highveld
Earth fault
Current is leaking to earth, often from damaged cable or motor insulation, or moisture in a junction box. Isolate, then disconnect the motor cables from the drive and test the cable and motor insulation resistance with an insulation tester.
Never run an insulation tester across drive terminals. The test voltage can destroy the drive. Disconnect the motor leads from the drive first.
Motor overload
The drive's thermal model of the motor tripped. This means the motor really is overloaded, or the overload setting does not match the nameplate current. Compare the set value against the nameplate.
When the drive itself has failed
A drive that will not power up, shows no display or trips with the motor disconnected may have failed internally. Send us the nameplate and fault details and we will help you decide between repair and replacement.