Thermistor Error

What does E35. mean?

This fault occurs when the inverter detects an abnormal temperature, indicated by a resistance value of 3 kΩ or more from an external thermistor connected to the TH input terminal. This suggests the motor temperature is too high, or there's a fault in the thermistor itself or its wiring, preventing accurate temperature monitoring.

• External thermistor (e.g., motor thermal protection) wiring open circuit or damaged, causing an infinite or very high resistance reading (>3 kΩ).
• Poor connection or corrosion at the TH input terminals on the inverter, creating a high resistance path perceived as an open circuit.
• The external thermistor itself has failed, and its resistance value is out of the expected range at ambient temperature.
• Inverter's internal input circuit for the TH terminal is defective or has developed a high resistance internally.

Click steps to track your progress.

1. 1

   Disconnect power. Measure the resistance of the external thermistor directly at its leads using a multimeter. Compare the reading to the thermistor's specification (e.g., 10 kΩ at 25°C).

2. 2

   Measure the resistance of the thermistor wiring from the thermistor to the TH and common (e.g., ACM) terminals on the inverter to check for an open circuit.

3. 3

   Inspect the TH and common (ACM) input terminals on the inverter for loose connections, corrosion, or physical damage. Ensure proper torque on screw terminals.

4. 4

   If the external thermistor and wiring are verified good, test the inverter's TH input circuit by connecting a known good resistor (e.g., 10 kΩ) across TH and ACM terminals.

5. 5

   Review parameter settings related to the thermistor input, such as H3-01 (External Trip Input selection) to confirm correct configuration for the TH terminal function.