Schneider MasterPact NW25 Air Circuit Breaker Unit

Module Feature

NW25 is the 2500A frame air circuit breaker of Schneider MasterPact NW series for low voltage power distribution.

It supports 3-pole or 4-pole configuration, two installation styles: fixed type and drawout withdrawable type. Multiple breaking capacity grades H1/H2/H3 available, Icu range 65~150kA @440V. Compatible with Micrologic 2.0/5.0/6.0 trip units for overload, short circuit, earth fault protection and power metering function. Drawout version has separate connected/test/disconnected positions for safe maintenance. Widely stocked as spare for power plant, refinery, data center main incoming and bus tie switchgear cabinet.

Working principle

Current flows through the breaker main contacts and current sensors inside.

Micrologic trip unit continuously monitors three-phase current, neutral current and earth leakage current. When abnormal condition such as overload, short circuit or ground fault is detected, trip unit triggers shunt release or undervoltage release to open main contacts rapidly and isolate fault circuit. It records fault current value and trip timestamp, supports Modbus communication for remote monitoring and alarm uploading.

Onboard components

Main contact assembly, arc extinguish chamber, current transformer set, Micrologic trip unit, shunt trip coil, undervoltage release, manual operating mechanism, auxiliary switch contacts, status indicator and metal frame housing.

LED indicators

Trip unit LCD screen displays three-phase current, power parameters, alarm and trip fault codes. Mechanical indicators show ON, OFF and TRIP status.

Hardware self‑diagnosis

Built-in supervision detects trip unit power loss, CT circuit fault, communication failure, internal hardware anomaly. Configuration and fault diagnosis are completed by Schneider EcoStruxure Power software.

Programming softwareEcoStruxure Power, used for protection curve setup, metering configuration, communication parameter setting and fault event log reading.

Electrical & Process Parameters

Model:NW25 Brand:Schneider Electric Device type:MasterPact 2500A frame Air Circuit Breaker Function:Overload, short-circuit and earth fault protection for low voltage main power distribution system

Mechanical & Structure

Mounting:Fixed or drawout withdrawable switchgear mounting Protection class:IP30 for front panel Housing:Heavy-duty metal ACB frame assembly

Environmental

Operating temperature:-5℃ ~ +70℃ Storage temperature:-40℃ ~ +85℃ Ambient humidity:5~95% non‑condensing

Certification:CE, IEC60947-2 Status:Original Schneider low voltage distribution ACB spare

Installation

Isolate upstream power before replacement or rack insertion.

Select correct 3P/4P and H1/H2/H3 rating, match Micrologic trip unit type, check secondary wiring of auxiliary contact and trip coil, download protection setting file, test closing/tripping and communication function after commissioning.

Interface

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

Diagnostic

Overload trip: Load current exceeds long time protection setting. Instantaneous short trip: Downstream short circuit, high fault current. Earth fault alarm: Ground leakage current exceeds setting value. Communication offline: Bus wire break, wrong Modbus address or trip unit fault.

Product Brief

NW25 air circuit breaker, Schneider MasterPact 2500A frame low voltage ACB spare for main incoming and bus tie power distribution switchgear cabinet replacement.