Single phase failure and cable short-circuit monitoring

Since monitoring the motor winding temperature of a compressor is relevant to safety, this function must also be protected against faults.

In the event of a single phase failure of the sensor cable in the temperature control circuit, the resistor value is detected as being too high (Temperature monitoring), and the compressor protection device locks out immediately.

Devices conforming to EN/UL60730 are additionally protected against cable short-circuits in the sensor cable, i.e. they are protected against too low resistance. A short-circuit in the temperature control circuit is identified as a fault which causes the compressor protection device to lock out immediately.

Devices with cable short-circuit monitoring can therefore not be used in simple circuits for evaluating switch signals, such as the signals of oil flow switches (Oil flow monitoring with SE-B*).