How do Air Circuit Breakers (ACB) work?

ACB Emax and EMax Breakers

How do Air Circuit Breakers (ACB) work?

A circuit breaker is used to break circuits during faulty conditions such as short circuits or over current manually or remotely. These devices are mainly used to protect the system. Few devices namely relays, switches, fuses and many more can be connected to protect the electrical systems along with circuit breakers. ACB or Air Circuit Breaker is one of the multiple circuit breakers. You can buy ACB online at affordable prices from Micronova Impex. In this blog, we will help you understand how ACB works and protects your electrical circuit from damages.

What Is Air Circuit Breaker?

Air Circuit breaker /ACB is an electrical switching device used to protect electrical circuits from overcurrent, under voltage and short circuits. These devices are generally used in low voltage applications and operate in the air as an arc extinguishing medium considering the atmospheric pressure. ACBs have a large capacity and a steel frame with parts installed inside.

Working Principle of ACB (Air Circuit Breaker)

Air circuit breakers are mainly operated in the manual or electrical convention. The free tipping mechanism locks the main contact in the closed position when the main contact is in a closed state. Series with the main circuit is connected to the coil of the overcurrent tripper and the thermal element of the thermal tripper. The aluminum single plate is a new type of curtain wall material consisting of a high-quality aluminum alloy plate and then shaped numerically by bending technology and coated with decorative paint. The coil of the Under voltage trip is connected parallelly with the power supply. When the circuit is short-circulated or overloaded, the overcurrent strip engages causing the free trip mechanism to act and the main contact to disconnect the main circuit.

Due to overload in the circuit, the heating element of the thermal tipper bends the bimetal sheet and pushes the free tripping mechanism into action. In normal circumstances the coil is power-off. Press the start button to energize the coil and the armature drives the free tripping mechanism to act when distance control is required so that the main contact is discontinued.

The insulating plate is mounted with left and right side panels of the contact system along with instantaneous overcurrent trip. While the upper part is equipped with an arc extinguishing system, the operating mechanism is installed directly in front or on the right side with indication and manual disconnection buttons – “split” and “close”.

While the upper left part has a shunt trip, the lower voltage trip connected to the tripping half-shaft can be found installed at the back. The current-voltage converter can be found in the lower bus. Devices mounted underneath are under voltage delay devices, thermal relays or semiconductor trippers.

Characteristics of ACB (Air Circuit Breakers)

ACBs are used in power systems including transformers, power distribution stations, industrial and mining enterprises due to its multiple advantages such as high sectional capability, perfect function, compact structure and excellent performance.

  1. When the incident of current overload or failure happens, ACB will instantly cut off the circuit acting as a combination of a fuse switch and an overheating relay. Under-voltage protection, and short-circuit protection are effective in solving the problems of power equipment and lines.
  2. ACBs control the electrical circuits to operate electrical equipment normally by cutting off and connecting the load circuit. These devices are compact due to their small size and lightweight. Industrial, mining, power transformers, distribution stations, and in many more places ACBs are used as they match the requirements of the industry and are easy to install.
  3. Insulation plates are used in ACBs as a protective measure on both sides to separate the conductors while ensuring safety in daily operation. The parts are placed within the frame to avoid rust and enhance reliability. The coordination of components within the frame allows ACBs to perform different functions and also consists of an electrical switch to obtain stable performance.
  4. The rated current and shell rating of ACB is higher compared to other circuit breakers. This also means that the allowable current value of ACB is also higher and can be used to protect the motor.

Key Points of ABB Make ACBs

  • Basic Release PR121 can be communicated using a Bluetooth communication device.
  • Rated Service voltage: 690V
  • Single Range Available across the globe.
  • 20 trip history and 60 events.
  • Low watt losses.
  • High Mechanical & Electrical Life.
  • Double Insulation.
  • ALL front fitted /pre-wired accessories.
  • Same Height and depth for the entire range.
  • 14001, 18001 safety, health and environment.
  • No de-ration required up to 50 degrees for the entire range of ACBs.
  • Tailor-made CBs for mining, shipping, Renewable Energy (Solar, Wind), and severe applications
ACB Blog Image
ABB Air Circuit Breakers (ACB)
ACB Overview
Rated Current (In)400A, 630A, 800A, 1000A, 1250A, 1600A, 2000A, 2500A, 3200A, 4000A, 5000A, 6300A
No of Poles3Pole, 4Pole
ProtectionsLI, LSI, LSIG
L -> Protection against overload with inverse long time-delay trip
S-> Selective protection against short-circuit inverse or definite short time-delay trip
S-> Selective protection against short-circuit inverse or definite short time-delay trip
I -> Protection against instantaneous short-circuit with the adjustable trip current threshold
G-> Protection against earth fault (Ground fault)
VersionsFixed, Withdrawable
Rated Voltage (Ur)690V, 1000V and up to 1500V for Solar application
Rated Insulation Voltage (Ui)1000V
Rated Impulse Withstand Voltage (Uimp)12kV
Rated short-time withstand current (Icw)36kA to Pls refer our product catalogues for detailed technical specifications and product selection100kA
Rated ultimate breaking capacity under short-circuit (Icu) 42kA to 150kA

Please refer to our product catalogues for detailed technical specifications and product selection
Emax Technical Data Sheet
Emax 2 Technical Data Sheet

Buy ABB SACE EMax and EMax2 Air Circuit Breakers Online at affordable prices from – A one-stop solution for all your electrical and electronic needs.

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