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1 phase over/under voltage relay MUS, MUSF

  • Three models with different voltage ranges
  • Reconnectable over or under voltage
  • Automatic detection of AC or DC
  • 17.5 mm cabinet with DIN rail

Product description

Control relay for 1-phase voltage monitoring, ac/dc. The relay requires no supply voltage but is instead powered by the measurement voltage that it simultaneously monitors (model MUS12DC is only for dc voltage). The MUS relays provide the user with the opportunity to choose between different control functions: Over- and under-voltage, with or without memory (if selected with memory, the power to the relay must be switched off to restart) and a time delay Tt to prevent minor temporary voltage changes (0.1-10 s). Adjustable hysteresis (H) is 5 to 20 % of the set value (applies only to MUS series). All settings are made at the front with a switch and if its setting is changed during operation, all LEDs begin to flash but the unit will continue to function normally with the voltage set at the most recent power connection. The MUSF relays have a window function, which means that the relay monitors the voltage that is between a lower and upper limit value. The limit values for over-/under-voltage are set with two potentiometers at the front that are scaled for the voltage (Un) to be monitored. MUSF has a static hysteresis of 3 %; function is otherwise the same as the MUS series. Green LED (Un) indicates supply voltage OK. Yellow LED (R) indicates active relay output.


Part numbers

Parts Price Lower limit Supply voltage Upper limit
9 V DC 12V dc 15 V DC
20 V AC/DC 24-48V ac/dc 80 V AC/DC
20 V AC/DC 24-48V ac/dc 80 V AC/DC
65 V AC/DC 110-240V ac/dc 260 V AC/DC
65 V AC/DC 110-240V ac/dc 260 V AC/DC


Crouzet voltage monitoring relay

Voltage Monitor Relay MUS12 9-15V dc

Technical data

Breaking capacity 5A, 250V AC/DC
Function Under/Overvoltage
Lower limit 9 V DC
Output Relay 1 pole C/O
Storage temperature max 70 °C
Storage temperature min -40 °C
Supply voltage 12V dc
Temperature operational max 50 °C
Temperature operational min -20 °C
Time delay startup 0,5 s
Time delay when exceeding the limit value 0,1-10s
Upper limit 15 V DC
Weight 80 g

Measurements and connections

Technical illustrations

  • Dimensions


  • Over/under voltage - without memory (MUS)<br />1: Limit value <br />2: Hysteresis<br />3: Over-voltage function<br />4: Under-voltage function<br />5: Monitored signal<br />6: Time delay upon exceeding limit value (Tt)

    Over/under voltage - without memory (MUS)
    1: Limit value
    2: Hysteresis
    3: Over-voltage function
    4: Under-voltage function
    5: Monitored signal
    6: Time delay upon exceeding limit value (Tt)

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