PTC Fault (Motor Overheating)

What does OtFL mean?

A motor overheating detected error from a PTCL (Positive Temperature Coefficient Logic) standard product. This indicates that the PTC thermistor embedded in the motor windings has exceeded its trip temperature, signaling a critical motor overheating condition. Continuous operation will severely damage the motor.

• Motor operating continuously above its rated current or in a high ambient temperature environment, leading to internal overheating.
• Blocked motor cooling fan or clogged motor cooling fins preventing adequate heat dissipation from the motor windings.
• PTC thermistor embedded in the motor windings has reached its trip resistance (e.g., > 1650 Ohms), indicating overtemperature.
• Incorrect wiring of the PTC thermistor to the drive's dedicated PTC input (e.g., LI6, PTC+ / PTC- terminals).
• Open circuit in the PTC thermistor cabling between the motor and the drive's input terminals (e.g., wire break or loose connection).

Click steps to track your progress.

1. 1

   Allow the motor to cool down completely, then measure the resistance of the PTC thermistor at the drive's input terminals (e.g., LI6) using a multimeter.

2. 2

   Compare the measured PTC resistance to its cold state (e.g., 20-250 Ohms at 20°C) and trip state (e.g., > 1650 Ohms) to confirm its operation.

3. 3

   Inspect the motor's cooling fan for proper operation and clean any dust or debris from the motor's cooling fins.

4. 4

   Verify the PTC thermistor cabling for continuity and correct connection from the motor to the drive's dedicated input terminals.

5. 5

   Check for mechanical overload on the motor; measure operating current and compare to nameplate rated current.