For a direct-on-line (DOL) motor, the protection chain is typically contactor + thermal overload (or motor protection breaker) + short-circuit protection. The overload is set to the motor rated current.
- Contactor — motor power and AC-3 utilization category
- Thermal overload — range covering the motor rated current
- Short-circuit — fuse or motor protection breaker (MPCB)
For motors run by a drive (VFD), the drive's electronic motor protection is used instead of a thermal overload; a classic overload can false-trip.
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