Phase & voltage monitoring relay with LCD display is used to monitor phase loss, phase sequence, voltage unbalance, overvoltage and undervoltage in the 3-phase power supply of 208-480V AC 50/60Hz. The monitoring relay is widely applied in the applications like 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
• Microprocessor technology provides highly accurate and repeatable protection
• LCD display and keypad afford a precise digital setting
• Adjustable overvoltage and undervoltage，phase unbalance threshold
• Independent adjustable delay time for overvoltage, undervoltage, voltage unbalance, phase loss and phase sequence
• Adjustable reset method: automatic reset or manual reset
• Start delay (power-on delay)
• Test trip with test button
• Monitoring relay with 1 CO & 1 NC contacts
• With timer and counter for running and faults

Specification

Wiring Diagram

Monitoring relay contacts position shown in "Power-on" (Healthy) condition

Dimensions (Unit: mm)

Details

Tips: Phase Failure and Phase Sequence Monitoring Relay Function

Generally, the wiring order of the motor is specified. If the phase sequence is disordered due to some reason, the motor will not work properly or even be damaged. Phase sequence monitoring relay is to prevent such accidents. Phase sequence protection can use phase sequence monitoring relays. When the phase sequence in the circuit does not match the specified phase sequence, the phase sequence relay will trigger the action and cut off the power of the control circuit to achieve the purpose of cutting off the motor power and protecting the motor.

Phase failure protection relay, or motor phase failure protector is generally used in three-phase motor circuits. If one line circuit is missing, the motor torque will become smaller and the rotor speed will decrease, resulting in the increasing current of other two circuits and the motor winding burning. The principle of phase failure monitoring relay is to monitor the three-phase power through different means: if there is a circuit break, the power will be automatically cut off by the relay to avoid burning the winding. Nowadays, the methods of phase-loss protection is to control the circuit on and off by monitoring the voltage of each channel or monitoring the current of each channel.

In the video below, RDDLZ will use the RDDLZ-MR-JVR8002 Multifunctional Monitoring Relay to monitor the three phase loss and reverse phase sequence when the 3-phase induction motor is running.