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    Multifunctional Monitoring Relay, Phase/Voltage, 3 Phase, 208-480V AC

    5 out of 5 based on 3 reviews | Write a review
    Phase voltage monitoring relay, used for phase loss, phase sequence, voltage unbalance, overvoltage and undervoltage monitoring with 3 phase power supplied by 208-480V AC 50/60Hz, also with timer & counter function, 0.1-30s adjustable delay time, compact size relay with 1 CO + 1 NC contacts, real-time LCD display for voltage, fault and operation state, DIN rail mounting. High accuracy and favorable price.
    SKU: ATO-MR-JVR8002
    30-day Returns
    Free Shipping
    Delivery date: 6-12 days

    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.


    • 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


    Model ATO-JVR800-2
    Measuring Circuit 3-Phase AC: L1, L2, L3
    Monitoring Functions Phase Sequence (Reversal), Phase Loss (Failure)
    Overvolatege, Undervoltage, Voltage Unbalance (Asymmetry)
    Timer & Counter
    Rated Voltage 208-480V AC, 50/60Hz
    Overvoltage Setting Range 200-600V
    Undervoltage Setting Range 150-500V
    Voltage Hysteresis 1-20V
    Delay Time for Overvoltage & Undervoltage 0.1-30s
    Voltage Unbalance Ratio 1-50%
    Voltage Unbalance Hysteresis 1-10%
    Delay Time for Voltage Unbalance 0.1-30s
    Delay Time for Phase Loss 0.1-30s
    Delay Time for Phase Sequence 0.1-30s
    Power On Delay Time 0-999s
    Reset Mode Manual/Auto
    Delay Time for Reset 0.1-999s
    Timer and Counter Input AC/DC 80-450V
    Indicator LCD display indicating voltage, fault and operation status
    Output Contacts 1 CO + 1 NC
    Contact Capacity 6A, 250V AC (resistive load)
    Degree of Protection IP 20
    Working Conditions Operating Temperature -25℃~65℃
    Humidity ≤85%RH, non-condensing
    Mechanical Durability 1,000,000 cycles
    Dielectric Strength >2kVAC 1min
    Mounting 35mm DIN rail
    Certification CE
    Weight 130g
    Dimensions (H*W*D) 80*43*54mm

    Wiring Diagram Multifunctional Phase Voltage Monitoring Relay Wiring Diagram

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

    Dimensions (Unit: mm)

    Multifunctional Phase Voltage Monitoring Relay Dimension


    Three Phase Voltage  Monitoring Relay 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, ATO will use the ATO-MR-JVR8002 Multifunctional Monitoring Relay to monitor the three phase loss and reverse phase sequence when the 3-phase induction motor is running.

    3-Phase Monitoring Relay Phase Failure & Phase Sequence Testing

    In this video, we will give you a test of ATO 3-phase monitoring relay on phase failure and phase sequence, and the relay does the job at such these cases to protect the motor. In addition, this multi-purpose monitoring relay has other monitoring functions such as undervoltage, overvoltage, voltage unbalance, timer & counter.

    Existing reviews of Multifunctional Monitoring Relay, Phase/Voltage, 3 Phase, 208-480V AC
    Question about phase
    Is it working with only 2 phases (2 x 120v inverted = 220v)?
    From: Clare | Date: 24/10/2023
    Was this review helpful? Yes No (0/0)
    ATO Responded
    This unit can Not be used as a 2-phase unit, it can only be used as a 3-phase unit.
    Do I need relay CTS or an access line?
    When using ATO-MR-JVR8002, do I need CTS or an access line?
    Do I need a CTS when using the ATO-MR-JVR8002, or do I need wiring, and can it handle 25-40 amps?
    From: sini | Date: 24/07/2023
    Was this review helpful? Yes No (0/0)
    ATO Responded
    1. You need to access the wires.
    2. AT-MR-JVR8002 detects voltage instead of current.
    These work great!
    This phase monitoring works like a champ and is so easy to set up and program.  My customer is extremely happy they now have a digital solution instead of the old turn-style analog relays they had before.  Thank you ATO, for the fast shipping and great product!
    From: Nathan | Date: 01/07/2021
    Was this review helpful? Yes No (0/0)
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