Glossary · Motion control and drives
Motor protection
Also known as: Motor overload protection
German: Motorschutz
In electrical engineering, motor protection is the set of devices and functions that protect a motor and its supply circuit against overload, short circuit, phase failure and overtemperature, for example motor protection circuit breakers, overload relays, thermistor relays or drive-internal protection.
- Motion control
- Standards
In one sentence
Motor protection guards motors and supply circuits against overload, short circuit, phase loss and overheating.
Example
Each conveyor motor is fed through a motor protection circuit breaker set to the nameplate current and a contactor.
How it applies
- Engineering: Protection is selected by motor rating, starting method and duty type. Frequency inverters usually include electronic motor overload protection; thermistors or temperature sensors in the winding add direct thermal protection.
- Commissioning: Overload settings are adjusted to the motor's rated current, not to the device's maximum.
- Operation: A tripped protection device must be reset deliberately after the cause is found; repeated resets without investigation can damage the motor.
- Documentation: State setting values in the electrical documentation and describe tripping, cause finding and reset in the troubleshooting section. Make clear that motor protection protects equipment; it is not a safety function for people.
Motor protection vs. safety function
Motor protection prevents damage to the motor and wiring. A Safety function reduces risk to people and must be designed and validated according to functional safety standards.