PTC Monitoring

What does OH51 mean?

The drive has triggered the PTC monitoring function. This indicates that the Positive Temperature Coefficient (PTC) thermistor, likely in the motor, has exceeded its threshold temperature, signifying an overtemperature condition. The drive continues to operate in a controlled manner.

• Motor operating at continuous overload conditions, causing windings to overheat and exceed the PTC thermistor's trip temperature.
• Blocked motor ventilation fan or cooling fins, preventing efficient heat dissipation from the motor casing.
• Incorrectly sized motor for the application, leading to continuous operation above its rated thermal capacity.
• Open circuit or poor connection in the PTC thermistor wiring from the motor to the drive's input terminals (e.g., X12).
• Faulty PTC thermistor in the motor providing an incorrect resistance reading to the drive.

Click steps to track your progress.

1. 1

   1. Measure the resistance of the PTC thermistor circuit at the drive's input terminals (e.g., X12) and compare it to the thermistor's specified resistance curve.

2. 2

   2. Visually inspect the motor's cooling fan and fins for obstructions or damage; clean or repair as necessary.

3. 3

   3. Reduce the motor's load by adjusting mechanical parameters or drive control settings to operate within its continuous rating.

4. 4

   4. Check the continuity of the PTC wiring from the drive's terminals to the motor's internal thermistor using a multimeter.

5. 5

   5. Monitor motor current (P0-04) and motor speed (P0-03) to ensure the motor is not being driven beyond its rated specifications for extended periods.