Description

Thermal motor protection without temperature sensor is an inverter function that can protect motors without temperature sensors (e.g. PTC thermistors, bimetallic switches) against overheating. The level of protection is similar to that of a thermal overload relay.

Thermal motor protection without temperature sensor has the following characteristics:

• Reduced cooling especially at lower speeds is taken into account.
• Insufficient cooling conditions and increased ambient temperature are not taken into account.
• In the event of overloads in the low speed range, 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. For motors with temperature sensor, the temperature sensor measures an overtemperature only at increased motor utilization and switches off the motor. This increased motor utilization is not possible with thermal motor protection without a temperature 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.