Cause : Inverter temp. signal lost comes when the drive cannot read the temperature of the heatsink, which is a critical component for preventing overheating.

The F0012 fault in Siemens Micromaster 440 indicates a inverter temperature sensor issue. This means the drive cannot detect the temperature of the heatsink.

Here are some steps to diagnose and potentially resolve the issue:

1. Check Connections:

   • Ensure all electrical connections to the temperature sensor are secure and properly connected.
   • Inspect for any loose or damaged wires.

2. Inspect the Temperature Sensor:

   • Verify that the temperature sensor is functioning correctly.
   • If possible, test the sensor with a multimeter to check for correct resistance values according to the sensor's specifications.

3. Verify Parameter Settings:

   • Check the parameter settings in the inverter's configuration. Ensure that the parameters related to the temperature sensor are correctly set.

4. Check for Overheating:

   • Ensure that the inverter is not overheating due to external factors such as a blocked cooling fan or high ambient temperatures.
   • Clean any dust or debris from the cooling fins and ensure proper ventilation.

5. Reset the Fault:

   • Attempt to reset the fault by turning off the inverter and turning it back on. Sometimes, a temporary glitch can cause such faults.