Eaton IZMX40H3-V12W Air Circuit Breaker Unit

Module Feature

IZMX40H3-V12W is Eaton Moeller IZMX40 series withdrawable air circuit breaker.

H stands for high short-circuit breaking capacity grade, 3 means 3-pole structure, V represents PXR20 selective protection trip unit, 12 corresponds to 1250A rated current, W is withdrawable drawer type. It adopts stored-energy spring operating mechanism, supports motor charging, electrical closing and tripping. PXR20 trip unit provides long time overload, short time delay, instantaneous short circuit and earth fault selective protection. It supports Modbus communication for remote status upload, parameter setting and fault record query. Compact depth design, widely used for power plant, petrochemical and factory low voltage main distribution cabinet maintenance spare.

Working principle

Built-in current transformers collect three-phase current signals and transmit to PXR20 trip unit.

Trip unit executes protection curve comparison in real time. When overload, short circuit or earth fault occurs, it sends trip command to release spring mechanism and separate main contacts rapidly to cut off fault circuit. Operation count, fault type, timestamp and waveform data are stored inside trip unit and uploaded to SCADA system via communication bus.

Onboard components

Main contact set, arc extinguishing chamber, spring energy storage mechanism, charging motor, closing and tripping coil, CT group, PXR20 protection trip unit, auxiliary contact block, drawer base, front operation handle and status indicator window.

LED indicators

Front indicators show breaker ON, breaker OFF, spring charged, fault trip and communication status. Detailed protection alarm information is displayed on PXR20 trip unit panel.

Hardware self‑diagnosis

PXR20 trip unit runs continuous supervision for trip coil continuity, CT circuit anomaly, internal power loss and hardware failure. Fault diagnosis, protection parameter commissioning and log reading are finished by Eaton PXR configuration software.

Programming software

Eaton PXR commissioning tool, used for protection curve setup, earth fault threshold, communication address and firmware upgrade.

Electrical & Process Parameters

Model:IZMX40H3-V12W Brand:Eaton Moeller Device type:IZMX40 withdrawable air circuit breaker Function:Overload, short circuit and earth fault selective protection for 3-phase low voltage main incoming and bus tie distribution circuit

Mechanical & Structure

Mounting:19-inch cabinet withdrawable drawer mounting Protection class:IP30 front panel, IP20 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 60947-2 Status:Original Eaton distribution spare

Installation

Isolate upstream power supply before replacement.

Install breaker into matching drawer compartment, lock secondary control wiring, set protection parameters according to power distribution design, test spring charging, close/trip action and protection trip function.

Interface

Primary copper bar connection terminal, secondary screw terminal block for auxiliary contact, trip coil and Modbus communication.

Diagnostic

Spring charging failure: Charging motor burnout, mechanical jam or limit switch damage. False earth fault trip: CT wiring reversed, neutral interference or threshold setting error. Communication offline: Bus terminal resistance mismatch, cable damage or PXR firmware mismatch.

Product Brief

Eaton IZMX40H3-V12W air circuit breaker, IZMX40 1250A 3P withdrawable ACB spare for industrial low voltage main incoming distribution cabinet replacement.