Thermal motor protection without temperature sensor

Thermal motor protection without temperature sensor is an inverter function that can protect motors without temperature sensors (e.g. PTC thermistors, bimetallic switches) against thermal overload. The level of protection is similar to that of a thermal overload relay. However, the reduced cooling is taken into account, especially at lower speeds.

• Insufficient cooling conditions and increased ambient temperature are influencing factors that cannot be taken into account.
• In the event of overloads in the low speed range, it cannot be ruled out that increased winding temperatures may occur which may damage the winding or lead to premature aging of the motor.
• The cooling of the motor is stronger at low temperatures. A temperature sensor only measures and triggers an overtemperature at increased motor utilization. This increased motor utilization is not possible with thermal motor protection without a sensor.

This means that thermal motor protection without a temperature sensor only represents basic protection. For complete thermal motor protection, SEW-EURODRIVE recommends using a temperature sensor.

• Requirements
• Boundary conditions
• Further information