Cause : Inverter temperature signal lost comes when wire breakage of inverter temperature (heatsink) sensor. This means the temperature of the heatsink within the drive, which helps regulate internal heat.

If you're encountering an "Inverter Temperature Signal Lost" error on a Siemens Micromaster 440, it typically means that the drive has lost communication with the temperature sensor that monitors the inverter's internal temperature.

Common Causes

1. Faulty Temperature Sensor: The temperature sensor itself may be defective.
2. Loose or Damaged Wiring: Wires connecting the temperature sensor to the drive may be loose, damaged, or disconnected.
3. Interference or Noise: Electrical interference or noise can disrupt the signal from the temperature sensor.
4. Drive Internal Fault: An internal fault within the drive could prevent it from reading the temperature sensor correctly.

Troubleshooting Steps

1. Inspect the Temperature Sensor:

   • Check the temperature sensor for any signs of damage or wear.
   • If possible, test the sensor with a multimeter to ensure it is functioning correctly.

2. Check Wiring Connections:

   • Inspect the wiring between the temperature sensor and the drive.
   • Ensure all connections are secure and free from damage.
   • Look for any signs of wear, fraying, or disconnection.