Eaton GNS31250T32WP09 NGS Air Circuit Breaker Unit

Module Feature

GNS31250T32WP09 is the 3-pole 1250A fixed type air circuit breaker of Eaton NGS series, equipped with Digitrip 310 electronic LSI trip unit.

It integrates long-time delay overload protection, short-time delay short-circuit protection and instantaneous short-circuit protection functions. The current rating can be adjusted by matching rating plug, which is convenient for on-site power distribution matching. It supports optional electrical closing, electrical tripping, breaker status auxiliary contact and fault alarm output. High short-circuit breaking capacity, metal enclosed frame, suitable for 19-inch switchgear cabinet installation. Widely stocked as maintenance spare for factory main incoming cabinet, data center power distribution and substation low-voltage bus protection.

Working principle

Current transformers collect three-phase load current and transmit signals to Digitrip 310 trip unit.

The electronic protection module judges whether it is overload, short-time short circuit or instantaneous short circuit according to the set curve. When the threshold is exceeded, the trip coil is driven to release the mechanical energy storage mechanism, and the main contact is quickly separated to cut off the fault circuit. The trip unit records fault current value and fault type, and uploads alarm signal to SCADA system through auxiliary contact.

Onboard components

Main contact group, arc extinguishing chamber, current transformer set, Digitrip 310 electronic trip unit, energy storage motor, closing coil, trip coil, auxiliary switch contact, status LED indicators, mechanical energy storage mechanism and metal frame.

LED indicators

Trip unit LCD / indicator: load current, overload pre-alarm, short-circuit fault, trip indication. Mechanical window: spring charged / discharged, breaker ON / OFF status.

Hardware self‑diagnosis

Built-in supervision detects trip unit power loss, CT signal anomaly, energy storage failure, coil disconnection and wiring fault. Configuration and fault diagnosis are completed by Eaton Digitrip setting software.

Programming softwareDigitrip software, used for LSI protection curve setting, rating plug matching, fault record reading and protection test.

Electrical & Process Parameters

Model:GNS31250T32WP09 Brand:Eaton Device type:NGS series air circuit breaker Function:Overload and short-circuit protection for low-voltage main incoming bus and large distribution circuit

Mechanical & Structure

Mounting:Fixed installation inside low-voltage switchgear Protection class:IP30 cabinet installation Housing:Heavy-duty metal breaker frame

Environmental

Operating temperature:-5℃ ~ +50℃ Storage temperature:-40℃ ~ +85℃ Ambient humidity:5~95% non‑condensing

Certification:CE, UL, IEC60947 Status:Original Eaton power distribution spare

Installation

Isolate upstream high-voltage power supply and implement locking before replacement. Check three-phase phase sequence, confirm control voltage for energy storage and closing coil, set LSI protection parameters and rating plug, test closing, tripping and protection action after commissioning.

Interface

Three-phase main bus terminal, control power terminal, electrical close/trip coil terminal, multi-channel auxiliary status contact terminal.

Diagnostic

Overload alarm: Load exceeds long delay setting. Short circuit trip: Instantaneous or short-time delay protection triggered. Cannot close: Spring not charged, interlock protection active, coil fault. Trip unit trouble: Auxiliary power missing, CT wiring open.

Product BriefGNS31250T32WP09 circuit breaker, Eaton NGS 3P 1250A air circuit breaker spare for low voltage main incoming and distribution switchgear cabinet replacement.