A motor trips, someone resets it and it runs again. Then it trips again the next day. The natural next step is to blame the motor, so it is tested, rewound or replaced. Sometimes that is right. Sometimes the motor was sound, and the cause sits in the drive, the controls or the supply feeding it.
Why a trip is a symptom, not a diagnosis
A trip is the protection doing its job. It tells you something went beyond a limit, such as current, temperature, voltage or an earth fault, but not why. Common causes include an overloaded or jammed machine, a loose or damaged connection, a poor supply, drive settings that no longer suit the load, heat building up in the drive or motor, and motor insulation that is deteriorating.
Start with what the equipment is already telling you
Most drives record fault codes and operating history. Reading them before anything is changed can narrow the search quickly. Note when the trip happens (at start-up, under load or after running for a while), what else was running and whether anything changed recently.
Isolate and lock off before any hands-on checks. Work on drives, controls and motors should only be done by competent people.
Separating the motor from the drive
Checks that help tell the two apart include inspecting connections and cabling, testing the motor windings and insulation, checking the drive output and settings, looking at cooling and ventilation, and confirming the driven machine turns freely. If the motor tests healthy, replacing it will not stop the trip. If the windings are damaged, fixing only the drive will not either. Sometimes both need attention.
Inverter drive repair or replacement: what to weigh up
- The age of the drive and whether spares and replacements are available.
- The fault found, and whether the cause has been removed so it does not return.
- How critical the machine is and what downtime costs the site.
- Whether the motor and drive should be assessed together.
Talk to EES Electro-Mechanical
Greater Manchester and the North West
EES Electro-Mechanical works across motor rewinds, drives and controls, pump repair and gearbox refurbishment for sites in Greater Manchester and the North West, so a trip can be looked at as a whole rather than treating the motor and the drive separately. If you have a motor that keeps tripping, talk to the team about checking the motor, the drive and the controls together. See the range of EES Electro-Mechanical services, call 0161 655 4421 or contact the team.
EES Electro-Mechanical is part of EES Group Holdings.