Three-phase voltage relay CP-734, Un=3x(50÷450)V+N, 3x1C contact

Voltage relay for protection of three-phase installations

The CP-734 voltage relay is a reliable device designed to monitor voltage in three-phase networks. It is used to protect receivers against the effects of voltage drops or phase failure, which is particularly important for sensitive devices and motors. It is an undervoltage relay that reacts to excessively low voltage in the network.

Application and functionality

The device finds application in both BMS/PLC installations and in direct control of electrical circuits. Thanks to its design, the CP-734 relay is ideal for protecting motors and other three-phase receivers from damage caused by operation at too low a voltage. Under normal operating conditions, the relay contacts are closed, allowing direct disconnection of protective circuits or powering contactors. In the event of a voltage drop on any of the phases below the set threshold (170-210V), the contact corresponding to that phase opens, interrupting the control circuit and disconnecting the powered receiver.

Construction and mounting

The relay is designed for mounting on a TH-35 (DIN) rail and occupies 3 modules (width 52.5 mm). It has screw terminals with a cross-section of 4.0 mm² with a tightening torque of 0.5 Nm, which ensures a secure and safe connection of the wires. The device is equipped with LEDs indicating the power supply status and the presence of voltage in each phase (green U LED for power supply, yellow L1, L2 and L3 LEDs for each phase). Additionally, it has a TEST button to simulate the relay's operation to check its functionality.

The relay is characterized by a supply voltage of 3×(50÷450)V + N and an adjustable operating voltage range from 170 to 210 V. It is equipped with three normally open (NO) contacts, which are closed with correct voltage and open in the event of a voltage drop. The maximum load current is 3 × 8 A, and the operating time is 0.5 s. The voltage hysteresis return is 5 V. The relay operates at a temperature of -20°C to +50°C and has a protection class of IP20. The minimum adjustable time delay in case of power failure is 0.5 s, and the maximum is 1.5 s. The device does not have a time lock and is compatible with generators, consuming only 0.8 W of power. This makes it an effective and reliable solution for protecting electrical installations from the effects of incorrect mains voltage.