Shunt Trip (MX) and Undervoltage Release (MN)

MX or MN Voltage Release

A voltage release can be used to trip the circuit breaker using a control signal.

Shunt trips serve primarily for remote, emergency-off commands. Undervoltage releases disconnect under low-voltage conditions.

Operating Voltages for MN/MX, Visible Through Front Cover

Installation and Connection

  • Voltage releases snap into a cavity under the front accessory cover of the circuit breaker.
    The presence and characteristics of the voltage release is visible from the front face through a window.

  • Each spring terminal may be connected by one 0.5–1.5 mm² (20–16 AWG) stranded copper wire.

For information on electrical characteristics and wiring recommendations of MN/MX, see Shunt Trip (MX) and Undervoltage Release (MN) Wiring Rules


  • The circuit breaker must be reset locally after being tripped by shunt trip (MX) or undervoltage release (MN).

  • Tripping by the shunt trip or undervoltage release has priority over manual closing; in the presence of a standing trip order such an action does not result in any closing, even temporarily, of the main contacts.

  • Endurance: 50% of the rated mechanical endurance of the circuit breaker.


  • MN/MX voltage releases comply with with UL 489, CSA C22.2 No. 5 and IEC 60947-2 Standards.

  • MN/MX voltage releases are Listed for field installation per UL file E103955 and Certified under CSA file 177007.

QR code for this page

Was this helpful?