The ABB 1SVR740700R2200 is a CM-MSS.23P thermistor motor protection relay with two changeover (2C/O) contacts, designed to monitor PTC thermistor sensors embedded in motor windings. It operates on a dual-range control supply of 110-130 VAC or 220-240 VAC, making it straightforward to integrate into panels with existing control transformers.
The CM-MSS.23P accepts a PTC thermistor loop from the motor. When the winding temperature exceeds the sensor's rated trip threshold (typically around 130-150 °C for Class F insulation), the relay's internal resistance rises sharply, and the output contacts change state. The 2C/O contacts can be wired to drop out the motor contactor coil and signal a PLC input. The dual-voltage supply (110-130 VAC or 220-240 VAC) is selected by bridging the appropriate terminals; no jumper or DIP switch is needed — just connect the line to the correct pair.