Thermistor Trip

What does E35 mean?

This fault is activated when an external thermistor, connected to the inverter's input terminals [5] and [L], detects that the motor temperature has exceeded a safe limit (typically above 3 kΩ ±10%). The inverter trips and turns off its output to prevent motor overheating and damage.

• Motor overheating due to continuous mechanical overload, insufficient motor cooling (e.g., blocked fan, dirty fins), or operation in a high ambient temperature.
• Faulty external thermistor providing an incorrect high-resistance reading (e.g., simulating an open circuit or high temperature).
• Poor connection or broken wire on the thermistor input terminals [5] and [L] leading to an open circuit.
• Inverter thermistor input circuit failure or parameter setting error (e.g., P5-10 Motor thermal protection).
• Motor operating at low speeds for extended periods without adequate cooling for its load profile.

Click steps to track your progress.

1. 1

   1. Disconnect the thermistor leads from terminals [5] and [L] at the inverter, then measure thermistor resistance (Ω) directly at the motor terminals; compare to motor datasheet for ambient temperature.

2. 2

   2. Inspect the thermistor wiring from the motor to the inverter for breaks, shorts, or loose connections, particularly at terminals [5] and [L].

3. 3

   3. Verify motor fan operation and ensure motor cooling fins are clean and free of obstructions.

4. 4

   4. Review motor load profile and ensure it is not consistently exceeding its rated torque; measure motor current (A) during operation.

5. 5

   5. Check parameter P5-10 (Motor thermal protection function) settings; ensure it is configured for the correct thermistor type (e.g., PTC/NTC) or disabled if not used.