Motor Overheat (NTC Input)

What does oH5 mean?

The motor temperature, as directly monitored via an NTC thermistor input, has exceeded the alarm level set in parameter L1-16 (or L1-18 for motor 2). This indicates the motor itself is running excessively hot, likely due to prolonged overload or high ambient temperatures. Sustained overheating can lead to irreversible damage to motor windings and premature motor failure.

• Actual motor overheating due to sustained overload, blocked ventilation, or high ambient temperature.
• Faulty NTC thermistor inside the motor providing an erroneous signal.
• Wiring fault (e.g., short circuit, high resistance connection) in the NTC thermistor feedback cable.
• Incorrect alarm threshold setting in parameter L1-16 (Motor 1 NTC Overheat Level) or L1-18 (Motor 2 NTC Overheat Level).
• Inadequate motor cooling airflow or a clogged motor cooling fan.

Click steps to track your progress.

1. 1

   Measure the resistance of the motor's NTC thermistor directly at the motor terminal box; compare to manufacturer data.

2. 2

   Measure the resistance of the NTC thermistor feedback cable at the drive's designated NTC input terminals.

3. 3

   Verify parameter L1-16 (or L1-18) is set according to the motor's thermal characteristics.

4. 4

   Check the motor's surface temperature using an infrared thermometer; ensure it is within safe operating limits.

5. 5

   Inspect the motor cooling fan for proper operation and ensure cooling air pathways are clear.

6. 6

   Monitor the drive's output current (A) using the digital operator; ensure it does not continuously exceed rated current.