Thermistor Disconnect

What does THo mean?

The thermistor used to detect motor temperature has become disconnected. This prevents the drive from accurately monitoring motor temperature, posing a significant risk of motor overheating and damage if the condition is not resolved.

• Motor thermistor wiring broken or disconnected between the motor and the drive's input terminals.
• Loose terminal connections at either the motor junction box or the drive's thermistor input terminals (e.g., TH1/TH2).
• The thermistor sensor itself has failed, creating an open circuit.
• Incorrect thermistor type or input configuration selected in the drive's parameters (e.g., L1-01 for thermistor input selection).

Click steps to track your progress.

1. 1

   1. Verify continuity of the thermistor wiring from the motor junction box to the drive input terminals (e.g., TH1/TH2) using a multimeter.

2. 2

   2. Check for loose screw terminals, corrosion, or signs of overheating at both the motor and drive connection points.

3. 3

   3. Measure the resistance of the thermistor directly at the motor leads; compare to specified resistance-temperature curve if available.

4. 4

   4. Inspect the thermistor wires for physical damage, pinching, or breaks along the entire cable run.

5. 5

   5. Ensure the correct thermistor input type is selected in drive parameters (e.g., L1-01 for thermistor input selection, PTC or NTC).

6. 6

   6. If the thermistor and wiring are confirmed good, replace the drive if the fault persists.