HUW9 690V 6300A Air Circuit Breaker

The HUW9 Air Circuit Breaker – Full-Featured Protection and Intelligent Selectivity

The HUW9 Automatic Circuit Breaker delivers comprehensive protection with intelligent selectivity. Spanning current ratings of 200A to 6300A across six frame sizes, the HUW9 operates at up to 690V AC—making it one of the most versatile options available. Designed by HUYU Electric, this ACB defends against overload, short circuits, and provides standard undervoltage protection. Its intelligent selective coordination ensures that a fault in one feeder does not bring down the entire system, effectively maintaining power to unaffected circuits.

The HUW9’s 1600A frame is an affordable entry-level option for mid-range switchgear, while its largest frame, the 6300A model, supports heavy low-voltage installations. All frames come with flexible fixed or draw-out mounting, bottom and top incoming, 12kV impulse withstand capability, 1000V insulation, and breaking time ≤30ms. Integration capabilities include communication interfaces for building management systems (BMS), PLC, and SCADA platforms. For customers switching from competitor ACB models such as Schneider Masterpact, ABB Emax, and Siemens 3WL, the HUW9 provides factory-direct OEM pricing with equivalent performance and full documentation.

Customized Protection Across Six Frame Sizes

With finer gradation across six frame sizes, the HUW9 allows precise matching of breakers to load demand, avoiding oversizing and unnecessary costs. The Icu rating scales from 50kA to 120kA, matching the protection needs for various low-voltage installations without risking over-expenditure. Except for the draw-out-only 6300A frame, all other frames come in fixed or draw-out configurations to suit different applications, with the 6300A model tailored for critical main incomer roles.

Technical Specifications

High-Performance ACB Direct from the Factory – Customizable Six-Frame Design

Buyer’s Guide

Selecting an ACB Breaker for Optimal Performance

Use this guide for selecting the best-fitting HUW9 air circuit breaker for main incomer and feeder applications.

1. Frame Size Selection

Six frame sizes offer right-sized options for electric load demands. The HUW9-1600 is ideal for mid-range feeders up to 1600A, while the HUW9-2500 handles a 2500A main incomer, providing cost and space efficiency. The largest frame, the HUW9-6300, delivers up to 120kA Icu in draw-out form for critical high-capacity systems.

2. Full Protection Suite

Standard features include overload, short-circuit protection, and integrated undervoltage protection to secure motor and sensitive gear from low voltage. Intelligent selective coordination ensures the nearest downstream breaker clears faults without affecting unaffected circuits.

3. Fixed vs Draw-Out Options

Choose fixed mounting for cost savings and compactness or draw-out configurations for improved access and maintenance. Note that the 6300A frame is only available as a draw-out model.

4. System Integration

Monitor breaker performance via live feedback on current, voltage, and condition using a communication interface. Integrate this into BMS, PLC, or SCADA setups for facilities prioritizing uptime and proactive fault management.

Frequently Asked Questions

What is an ACB breaker?

An ACB breaker — Air Circuit Breaker — is a high-current protection device that uses atmospheric air to extinguish the electrical arc when the contacts open. It is installed at the main incomer and large feeder positions in low-voltage switchboards, typically rated from 630A to 6300A. The HUW9 is an ACB breaker that adds undervoltage protection and intelligent selective coordination to the standard overcurrent and short-circuit functions.

What is the difference between ACB and MCCB breakers?

An MCCB (Moulded Case Circuit Breaker) is a compact, enclosed device rated up to 1600A, used for branch circuit protection. An ACB is an open-frame device rated from 630A to 6300A, designed for main incomer and large feeder applications. The key differences: ACBs have higher breaking capacity (up to 120kA), offer draw-out configurations for maintenance without panel shutdown, include programmable electronic protection and communication, and have replaceable components. An MCCB is typically a sealed unit and replaced as a whole after major faults. The HUW9 is an ACB; HUYU’s MCCB range covers branch protection up to 1600A.

Why is ACB used in LT panels?

ACB is used in LT (Low Tension) panels for three main reasons. First, it handles the high current ratings (up to 6300A) required at the incomer of a building or industrial switchboard — beyond the practical range of MCCBs. Second, its high breaking capacity (up to 120kA at 400V for the HUW9-6300) safely clears the large prospective fault currents present at the main busbar. Third, the draw-out design allows the breaker to be isolated and removed for maintenance without shutting down the entire panel — critical for facilities where power continuity is essential.

What causes ACB to trip?

An ACB trips under four common conditions. Overload — current exceeds the rated value for an extended period, typically caused by too many loads on one circuit. Short circuit — a direct fault between phases or phase to earth, producing instantaneous high current that the breaker must clear within ≤30ms. Undervoltage — supply voltage drops below the preset threshold, which the HUW9 detects as a standard protection function, disconnecting the circuit to prevent equipment damage. Earth fault — leakage current to earth detected by the intelligent controller when configured with the appropriate protection module. After any trip, the HUW9’s controller records the fault type and current magnitude to assist with diagnosis.