Voltage Releases

Introduction

The following voltage release auxiliaries are operated remotely by an electrical trip command:

MX shunt trip
MN undervoltage release
MN undervoltage release with time-delay unit. The time-delay unit helps to overcome nuisance tripping due to transient voltage dips. The time delay is adjustable up to three seconds.

NOTE: It is recommended to test the operation of a voltage release at regular intervals, such as every six months.

Voltage release auxiliaries are installed in the case under the front face of the circuit breaker. The presence and characteristics of a voltage release auxiliary are displayed through a window on the front face.

For more information about installation, consult the instruction sheet on the Schneider Electric website: EAV91202 MN/MX Voltage Releases - Instruction Sheet

MX Voltage Release Installation Demonstration Video

To access a demonstration video about the installation of an MX voltage release in a ComPacT NSXm circuit breaker, click the following link: https://youtu.be/kT19RO1fXT8, copy and paste the link to your Web browser, or scan the QR code.

Characteristics

The characteristics of voltage release auxiliaries comply with IEC/EN 60947-2 recommendations.

Name	Image	Description
MN undervoltage release		Trips the circuit breaker when the voltage is less than 0.35 times the rated voltage (Un). If the voltage is between 0.35 and 0.7 times the rated voltage (Un), tripping can occur but is not certain to occur. If the voltage is above 0.7 times the rated voltage (Un), tripping cannot occur. Allows the circuit breaker to be closed again when the voltage reaches 0.85 times the rated voltage (Un). Use this type of accessory for failsafe emergency stops.
Time-delay unit for MN undervoltage release		Removes nuisance tripping of an undervoltage release by setting a time delay of up to 3 s to overcome transient voltage dips. Adjustable and fixed time-delay units are available.
MX shunt trip		Trips the circuit breaker when the voltage exceeds 0.7 times the rated voltage (Un). NOTE: MX shunt trip 110/130 Vac combined with Class I ground-fault sensing element is suitable for ground-fault protection. In this application, the circuit breaker trips when the voltage exceeds 0.55 times the rated voltage (Un).

Name

Image

Description

MN undervoltage release

Trips the circuit breaker when the voltage is less than 0.35 times the rated voltage (Un).
- If the voltage is between 0.35 and 0.7 times the rated voltage (Un), tripping can occur but is not certain to occur.
- If the voltage is above 0.7 times the rated voltage (Un), tripping cannot occur.
Allows the circuit breaker to be closed again when the voltage reaches 0.85 times the rated voltage (Un).

Use this type of accessory for failsafe emergency stops.

Time-delay unit for MN undervoltage release

Removes nuisance tripping of an undervoltage release by setting a time delay of up to 3 s to overcome transient voltage dips.

Adjustable and fixed time-delay units are available.

MX shunt trip

Trips the circuit breaker when the voltage exceeds 0.7 times the rated voltage (Un).

NOTE: MX shunt trip 110/130 Vac combined with Class I ground-fault sensing element is suitable for ground-fault protection. In this application, the circuit breaker trips when the voltage exceeds 0.55 times the rated voltage (Un).