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    Under/Over Voltage Monitoring Relay, LCD, 3 phase 3-wire/4-wire

    Under/Over Voltage Monitoring Relay, equipped with an LCD display and is suitable for 3-phase 3-wire or 4-wire power systems. This voltage monitoring relay is exquisitely designed and powerful, aiming to provide reliable voltage monitoring and protection, ensuring the stable operation of the power system.
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    Delivery date: 6-12 days

    The Under/Over Voltage Monitoring Relay, featuring an LCD display and tailor-made for 3-phase 3-wire or 4-wire power systems, offers efficient and reliable performance across a voltage range of 150V to 600V for 3-wire configurations and 80V to 350V for 4-wire setups, making it an ideal choice for monitoring and protecting your power systems. Feel free to contact us for more details or to place an order.

    This voltage monitoring relay finds applications in various scenarios including controlling the connection of moving equipment such as site equipment, agricultural machinery, and refrigerated trucks. It also serves to protect personnel and equipment from the consequences of reverse running and facilitates switching between normal and emergency power supplies. Additionally, the monitoring relay provides protection against phase failure to ensure stable and safe system operation.


    • Controls its own supply voltage (True RMS measurement).
    • LCD display.
    • Measuring frequency range: 45Hz-65Hz.
    • Voltage measurement accuracy<1%.
    • 2-MODULE, DIN rail mounting.
    • Ultra-small volume, only 36mm wide, with 35mm rail installation.


    Function Monitoring L-N voltage (3-phase 4-wire system) Monitoring L-L voltage (3-phase 3-wire system)
    Monitoring terminals L1-L2-L3-N L1-L2-L3
    Supply voltage limits 70V-400V 130V-650V
    Rated supply frequency 45Hz-65Hz
    Voltage hysteresis 2% Un
    Measuring range 80V-350V 150V-600V
    Measurement error ≤1%
    Phase failure 50% Un
    Start-reset delay time 0.3-30s
    Temperature coefficient 0.05%/℃, at=20°C (0.05%°F, at=68°F)
    Output 2×SPDT
    Current rating 8A/AC1
    Switching voltage 250VAC/24VDC
    Min.breaking capacity DC 500mW
    Mechanical life 1×107
    Electrical life (AC1) 1×105
    Operating temperature -20℃ to +55C (-4°F to 131°F)
    Storage temperature -35℃  to +75℃ (-22°F to 158°F)
    Mounting/DIN rail Din rail EN/IEC 60715
    Protection degree IP40 for front panel/IP20 terminals
    Operating position any
    Operating altitude ≤2000m
    Overvoltage cathegory Ⅲ.
    Pollution degree 2
    Max.cable size (mm2) solid wire max.1×2.5 or 2×1.5/with sleeve max.1×2.5 (AWG12)
    Dimensions 90×36×64mm
    Weight 90g
    Standards EN 60255-1, IEC 60947-5-1

    Wiring Diagram

    Voltage monitoring relay wiring diagram

    Functions Diagram

    • Phase failure and phase equence function diagram

    Phase failure function diagram

    • Overvoltage and undervoltage function diagram

    Overvoltage and unovervoltage function diagram

    • Asymmetry function diagram

    Asymmetry function diagram

    To: Overvoltage threshold tripping delay.
    Tu: Undervoltage threshold tripping delay.
    Ta: Asymmetry threshold tripping delay.
    Tr: Power up delay.

    Dimensions (mm)

    Voltage monitoring relay lcd dimension

    Tips: Enhancing Power System Stability with Under/Over Voltage Monitoring Relay

    With increasing power demands and the rising complexity of power systems, maintaining a stable voltage supply becomes crucial. In such scenarios, the application of Under/Over Voltage Monitoring Relays becomes particularly significant. Equipped with LCD displays, these monitoring relays can continuously monitor voltage fluctuations, promptly detecting and responding to voltage anomalies. Especially in 3 phase 3-wire or 4-wire systems, these relays play a pivotal role, providing users with precise voltage monitoring and protection. By delving into the applications of these technologies, we can better understand how to utilize these advanced tools to enhance power system stability, ensuring the reliability and continuity of power supply.

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