Weg RPW Range PTC Monitoring Relay

The RPW-PTC relay – designed and manufactured by the world-class electric motor manufacturer WEG (Brazil) – is an electronic device that provides monitoring of motors, generators and others, whose stator windings and bearings are equipped with thermistor protection. The relay switches off at the moment the temperature of the PTC sensor exceeds the maximum value specified by the manufacturer. It avoids overheating of the equipment to be protected, as a result, it ensures safe operation, extends lifetime and reduces maintenance costs on the machine.
Technology
The thermistor monitoring relay RPW-PTC was designed according to international standards. Its housing is 22.5 mm wide and can be inserted on DIN rail 35 mm, making the WEG relay a compact and easy-to-assemble solution. This product allows connection of several sensors in series (the total resistance value of the PTCs cannot exceed 2.3 kΩ). The relay can operate with a wide range of control voltage from 24 to 240 V, both AC (50 or 60 Hz) or DC.
Operation
The RPW-PTC relay has status indication through the LEDs located on the front of the product. The green LED is ON when the relay is energized. If the monitored temperature by the PTC is below the defined value of 3.5 kΩ, the red LED will be ON indicating normal operation. Therefore, if the resistance exceeds the limit of 3.5 kΩ, the relay will instantaneously switch the output contacts and the red LED will be OFF indicating an over temperature condition of the motor. The relay will only switch on the 15 and 18 contacts again once the temperature goes down to normal values. Additionally, the WEG PTC relay provides sensor testing feature. In case of failure of the PTC sensors, the green LED will be FLASHING. This feature indicates that the PTC sensors are either open or in shortcircuit (20Ω or less).