When the engine knocks out the machine, the protection does not work for nothing - it reacts to overcurrent. It is important to understand at what point this happens: when turned on, during startup, or under load. The reason depends on this.
When exactly the machine is triggered
- Immediately upon switching on, before starting.Almost always a short circuit in the winding, cable or a breakdown on the housing.
- At the moment of starting.The starting current may be too high, the rating of the machine is too low or the rotor is jammed.
- After a while under load.Overload, interturn short circuit, overheating.
Main reasons
| Cause | Check |
|---|---|
| Winding short circuit | Winding resistance with a multimeter |
| Breakdown to housing | Measuring insulation with a megohmmeter |
| Overload | Current in comparison with the nominal |
| Incorrect rating of the machine | Compare with the motor passport |
| Jagging | Rotate the shaft manually |
Why start
- Turn off the engine and check whether the shaft rotates.
- Measure the resistance of the windings - it should be the same across phases.
- Check the insulation on the housing with a megger.
- Compare the rating of the machine with the motor current.
If the windings “ring” among themselves or on the housing, the motor needs rewind. If the electrics are normal, but the shaft does not rotate, the problem is in the bearings.
Do not try to “defeat” the protection by installing a machine of a higher denomination - this is a direct path to a fire. The correct way is diagnosis and eliminating the cause. Elektromotors engineers in Tashkent will find the source of overcurrent and eliminate it - leave a request.