Cause : Inverter temperature signal lost comes when the inverter has lost communication with the temperature sensor responsible for monitoring critical temperatures within the system.

F12 fault in siemens V20 Drive indicate Inverter temperature signal lost. This means the drive is unable to communicate with the temperature sensor within the inverter.

Here's a systematic approach to resolving this issue:

1. Check Sensor Connections: Start by inspecting the connections between the temperature sensor(s) and the inverter. Ensure that the sensor cables are securely connected to the designated terminals on the inverter and that there are no loose connections or broken wires.

2. Inspect Sensor Health: Verify the condition of the temperature sensor(s). Ensure they are not damaged or malfunctioning. If possible, test the sensors using a multimeter or other appropriate tools to confirm that they are providing accurate readings.

3. Review Sensor Configuration: Check the inverter's configuration settings to ensure that the correct type and number of temperature sensors are configured. Make sure that the inverter is set up to monitor the temperature of all relevant components according to the system requirements.

4. Check Sensor Placement: Ensure that the temperature sensor(s) are installed correctly and positioned appropriately to measure the temperature of the targeted components accurately. Incorrect sensor placement can lead to inaccurate readings or loss of signal.

5. Inspect Wiring and Grounding: Verify that the wiring for the temperature sensor(s) is correctly routed and grounded as per the manufacturer's recommendations. Poor wiring or grounding can result in signal loss or interference.