EXW3 Air Circuit Breaker – 1600A 1250A 2500A 6300A

Intelligent Power Distribution via Air Circuit Breakers

The EXW3 is a flexible solution, capable of delivering an affordable Air Circuit Breaker (ACB) solution for your project, whether you need an air circuit breaker rated to 2000A for a commercial building or an 800A ACB for an industrial feeder or any application in between. The EXW3 is available in three different frame sizes from 400A to 6300A, rated at 690V AC, and designed for use as incoming main distribution circuit breakers in industrial facilities, commercial buildings, data centres, and power systems that support infrastructure. The EXW3 has breaking capabilities between 85kA and 125kA Icu at 400/415V and can be configured for use in main distribution switchboards with the largest prospective fault levels expected in low-voltage systems.

The EXW3 is more advanced than traditional ACBs because it uses an intelligent controller. With the EXW3 intelligent controller, you receive many robust features, including real-time current monitoring, fault recording, and programmable protection settings for overload, short-circuit, ground fault, and phase imbalance. The EXW3 also provides communication modules that allow the EXW3 to be incorporated into any building management system (BMS), SCADA system, or plant-wide power monitoring systems. Additionally, the design of the EXW3 is modular in nature, so components such as the controller, trip unit, and arc chutes are all field-replaceable. Because of this, downtime and maintenance costs to the ACB over its lifetime are significantly lower. If you are an ACB user of Schneider (Masterpact), ABB (Emax), Siemens (3WL, 3WT), Eaton (IZM), GE, Terasaki (Tempower), or L&T, you will find that the EXW3 is the perfect substitute for your ACB, but you will also enjoy factory-direct OEM/ODM pricing benefits from HUYU Electric.

Performance Parameters – ACB Frame Size and Breaker Current Ratings

Technical Specifications

Factory-Direct ACB Supply for Switchboard Builders and Project Buyers

Buyer’s Guide

How to Specify an Air Circuit Breaker – Frame Size, Breaking Capacity & Installation Type

An easy guide to choosing the correct EXW3 ACB product for main incomer and large feeder applications.

1. Choosing the Frame Size and Current Rating

To select the appropriate frame size for your motor protection circuit breaker, determine the maximum load current that will continuously flow through the circuit breaker. The EXW3-2000 has a continuous rated load current range from 630A through 2000A, including 800 amp and 1250 amp circuit breakers, making it an ideal product for larger commercial feeder applications. The EXW3-4000 has a continuous rated load current range of 2000A through 4000A, including a 2500A rating for industrial main switchboards. The EXW3-6300 has a continuous rated load current range from 4000A to 6300A for larger low-voltage incomers. Check the neutral pole rating: EXW3-2000 and EXW3-4000 have a 100% In neutral; EXW3-6300 has a 50% In neutral.

2. Selecting Breaking Capacity (Icu and Ics)

The EXW3 offers standard (N) and high (H) breaking capacity variants. At 400/415V, the Icu ranges from 85kA to 125kA. The correct selection depends on the prospective short-circuit current at the point of installation, calculated from the supply transformer rating, impedance, and cable length. Over-specifying Icu adds cost, while under-specifying risks breaker failure during a fault. For 690V systems, verify the derated Icu values (50kA–100kA). The Icw (1-second short-time withstand) must also support the selectivity delay with downstream devices.

3. Fixed vs. Withdrawable Installation

Fixed circuit breakers are bolted directly onto the busbar and chassis assembly, making them simpler and more economical to mount. However, the entire switchboard must be de-energised for maintenance. Withdrawable circuit breakers are mounted to a rack-out carriage, allowing isolation and removal for service without de-energising the busbar. EXW3 withdrawable circuit breakers include mechanical interlocks to prevent racking under load. Choose withdrawable breakers for critical main incomers to minimise maintenance-related downtime. Opt for fixed breakers for feeders with acceptable scheduled downtimes.

4. Intelligent Controller & Communication

The EXW3’s intelligent controller offers programmable protection settings for overload, short circuit, earth fault, and phase imbalance, along with trip event logs. It monitors phase currents and voltages and can communicate via Modbus or Ethernet to BMS and SCADA systems. For facilities without dedicated power monitoring, the controller’s local display provides sufficient information for routine checks. Specify the communication module at the point of order when external system integration is required.

Frequently Asked Questions

What is an air circuit breaker?

An air circuit breaker (ACB) is a high-current circuit breaker that uses air as the arc-extinguishing medium. When the contacts open under fault conditions, the arc is drawn into an arc chute where it is split, cooled, and extinguished. ACBs are used at the main incomer and large feeder positions in low-voltage switchboards — typically from 630A to 6300A. The EXW3 is an ACB covering this range with intelligent protection, 85kA–125kA breaking capacity, and both fixed and withdrawable configurations.

What is the difference between an air circuit breaker and a normal circuit breaker?

A “normal” circuit breaker usually refers to a miniature circuit breaker (MCB) or moulded case circuit breaker (MCCB) — devices rated up to 1600A that use an enclosed moulded case and interrupt arcs within a confined chamber. An air circuit breaker (ACB) is a larger, open-frame device rated from 630A to 6300A, designed for main incomer and large feeder positions. ACBs use atmospheric air as the arc-extinguishing medium, have programmable intelligent protection controllers, and are available in withdrawable configurations for rack-out maintenance. The EXW3 is an ACB; HUYU’s HUM and EXB series MCBs and MCCBs are “normal” circuit breakers for branch circuit protection.

How does an air break circuit breaker work?

An air break circuit breaker extinguishes the electrical arc in air — specifically, in an arc chute. When the breaker trips, the main contacts separate and the arc forms between them. Magnetic forces push the arc upward into an array of metal plates (the arc chute), which splits the single arc into multiple smaller arcs in series. Each sub-arc has a lower voltage drop, and the combined effect cools and extinguishes the arc within milliseconds. The EXW3 achieves breaking times of ≤30ms using this principle, with arc chutes that are field-replaceable as part of the breaker’s modular design.

What is the function of air breaker?

An air breaker (ACB) serves three primary functions in a power distribution system. First, it provides overcurrent protection at high current levels — opening the circuit during overload or short circuit to protect the busbar, cables, and downstream equipment. Second, it acts as an isolation device — particularly in withdrawable configurations — allowing a section of the switchboard to be de-energised for maintenance. Third, with an intelligent controller, an ACB provides power monitoring, fault recording, and selective coordination with downstream protection devices. The EXW3 is positioned at the main incomer and large feeder positions where all three functions are required.