Danfoss · VLT AutomationDrive FC 301/302
The temperature sensor connected to the drive's input is either not detected, improperly connected, or providing an invalid signal. This prevents the drive from accurately monitoring temperature.
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Power down the drive, disconnect the temperature sensor wires from the drive's input terminals (e.g., 53/54).
Measure the resistance of the temperature sensor across its leads; compare to the sensor's specified temperature/resistance curve (e.g., PT100 should be 100 Ohms at 0C).
Inspect the entire length of the sensor wiring for breaks, insulation damage, or loose connections.
Verify the analog input configuration parameters (e.g., P6-10 Analog Input Type, P6-11 Analog Input Low Value, P6-12 Analog Input High Value) are correct for the installed sensor.
Temporarily connect a known good reference resistor (e.g., 100 Ohm for PT100) to the input terminals to simulate a valid sensor reading.