MN31W12 Air Circuit Breaker Unit

Module Feature

MN31W12 is GE AEG M-PACT Plus series fixed / withdrawable air circuit breaker for low voltage power distribution.

It is designed for main incoming and bus tie application of industrial power distribution system, with built-in microprocessor protection unit for long-time overload, short-time delay short circuit, instantaneous short circuit and earth fault protection. It supports electrical closing and tripping, with spring charging mechanism and local manual operation function. It carries event recording, fault waveform capture and communication interface for uploading status and fault data to SCADA. It belongs to old discontinued M-PACT series, widely stocked as critical maintenance spare for factory and power plant low voltage switchgear cabinet.

Working principle

Current transformers inside breaker collect three-phase and neutral current signals.

Protection unit executes real-time current comparison and protection logic judgment. When abnormal overload or short circuit occurs, it triggers trip coil and mechanical release to cut off power loop rapidly. All operation count, fault type and time stamp data are stored in internal memory for post-fault analysis. It can realize remote opening/closing and interlocking with other protection devices via communication bus.

Onboard components

Current transformer group, electronic protection trip unit, spring charging motor, closing/tripping coil, arc extinguishing chamber, main contact set, auxiliary contact block, status LED, operation handle, communication circuit and metal frame.

LED indicators

Front LEDs indicate power normal, spring charged, breaker ON, breaker OFF, overload warning, short circuit fault and communication status.

Hardware self‑diagnosis

Built-in supervision detects trip coil continuity, CT circuit anomaly, internal power loss and protection unit hardware failure. Fault diagnosis and protection parameter setting can be completed by GE matching configuration software.

Programming software

GE protection configuration tool, used for protection threshold, time curve, communication address and interlock logic setup.

Electrical & Process Parameters

Model:MN31W12 Brand:GE AEG Device type:M-PACT Plus low voltage air circuit breaker Function:Overload, short circuit and earth fault protection for LV main incoming and bus coupling distribution circuit

Mechanical & Structure

Mounting:Switchgear cabinet fixed or withdrawable installation Protection class:IP30 front panel, IP20 internal terminal compartment Housing:Heavy-duty insulated industrial ACB housing

Environmental

Operating temperature:-10℃ ~ +55℃ Storage temperature:-40℃ ~ +85℃ Ambient humidity:5~95% non‑condensing

Certification:CE, IEC 60947 Status:Original legacy GE distribution spare

Installation

Isolate upstream power supply before replacement.

Check wiring of primary power loop and secondary control circuit, set protection curve according to distribution design, test closing/tripping action and protection trip function after commissioning.

Interface

Primary copper bar connection terminal, secondary screw terminal block for control, trip coil and communication signal.

Diagnostic

Protection false trip: CT wiring error, protection parameter mis-set or earth loop interference. Cannot close: Spring not charged, closing coil fault or interlock condition not satisfied. Communication offline: Bus terminal resistance mismatch, communication wire broken or address conflict.

Product Brief

GE AEG MN31W12 air circuit breaker, M-PACT Plus low voltage main breaker spare for industrial substation power distribution cabinet replacement.