3 Phase Monitoring Relay, SPDT, Phase Failure/Undervoltage/Overvoltage

Three phase monitoring relay with SPDT (1 C/O) contact, performs the monitoring functions including phase loss, phase sequence, phase unbalance, overvoltage and undervoltage in the 3 phase AC power system of 220V AC, 380V AC, 440V AC, 460V AC, or 480V AC 50/60Hz. The phase failure/voltage monitoring relay is widely applied in air compressors, electric motors, pumps, fans, air-conditioning system, blowers, lifts, elevators, cranes, refrigeration units, mining excavators and conveyors, etc.

Features

• Compact size in DIN rail mounting
• Three-phase monitoring of phase sequence, phase loss (phase failure), phase unbalance, overvoltage and undervoltage
• Powered by the measuring circuit
• Monitoring relay with 1 C/O (SPDT) contacts
• 5 LED lights for status indication

Specification

Wiring Diagram

Monitoring relay contacts position shown in "Power-off" condition

Dimensions (Unit: mm)

Details

Tips: Working Principle of Phase Sequence Monitoring Relay

Sampling three-phase power supply for processing, when the phase sequence of the power supply matches the phase sequence of the input of the phase sequence monitoring relay, the output of the relay is turned on, and the main control circuit of the device is turned on.

When the phase sequence of the power supply changes, the phase sequence does not match, and the output of the phase sequence monitoring relay cannot be turned on, thereby protecting the device and avoiding accidents. The other type of phase monitoring relay uses digital micro-core technology products, which can realize automatic phase sequence identification and automatic phase sequence conversion to ensure that the motor rotates in a constant phase sequence.

The three-phase power supply is connected to the U, V, W (some are R, S, T or L1, L2, L3) of the monitoring relay in sequence. The phase sequence monitoring relay generally have one normally open and one normally closed auxiliary contacts. For the connection to the control loop, the specific connection of normally open or normally closed contacts should be based on the control principle or wiring diagram. When the phase sequence is wrong or the phase is losing, the auxiliary contact of the relay acts from normally open to normally closed, and normally closed to normally open.