ACB & MCCB – An Introduction

Published on : Tuesday 02-05-2023

What is an air circuit breaker? This article explains the concept.

An air circuit breaker is an automatically operated electrical switch that uses air to protect an electrical circuit from damage caused by excess current from an overload or short circuit. Its primary function is to interrupt current flow after a fault is detected. These are usually used in low voltage applications below 450V.
 
Air circuit-breaker construction
The external part of air circuit breaker  mainly include the On & Off button, an indicator for the position of the main contact, an indicator for the mechanism of energy storage, LED indicators, RST button, controller, rated nameplate, handle for energy storage, displays, shake, fault trip rest button, rocker repository, etc.
 
The internal parts of air circuit breaker mainly include supporting structure with steel sheet, the current transformer used to protect the trip unit, pole group insulating box, closing springs, CB opening and closing control, plates to move arcing and main contacts, plates for fixed main and arcing contacts.
 
Advantages of an air circuit breaker

i. High-speed re-closures facility
ii. Used for frequent operation
iii. Need less maintenance
iv. High-speed operation
v. Fire risk can be eliminated not like in oil circuit breakers, and
vi. Consistent and short arcing time, so burning of contacts is less.
 
The world of electrical power distribution changes fast and major new trends such as energy efficiency, connectivity and smart grids are now crowding onto the stage. These trends lead to new applications and market requirements that ABB SACE low voltage circuit breakers are able to satisfy with high quality, accuracy and reliability.
 
There are two types of Formula air circuit breakers, moulded case circuit breakers and air circuit breakers, from 160 to 6300A.
 
Low voltage Formula air circuit breaker
Formula Air is the new line of low voltage automatic circuit-breakers. Easy to order, use and install, the Formula Air series offers all of the standard performance levels, quality and reliability you would expect from ABB technology.
 
Formula Air is an ideal solution for main installation requirements, from distribution switchboards to onboard compartments. This comprehensive range offers the most suitable solution for each specific set of requirements.
 
Easy to use Formula Air products are also easy to order.
 
The automatic circuit-breakers and switch disconnectors are available in three sizes A1, A2 & A4 from 800A to 4000A, with short-circuit performance levels up to 50kA.
 
The installation of Formula Air and its accessories is simple, quick and safe. The accessories, pre-cabled and common to all the three frames, allow for rapid mounting and a significant reduction in warehouse stock.
 
It is actually possible to change, on site, the orientation of the rear terminals from horizontal to vertical or vice versa. If you need a switchboard with more compact dimensions, front terminals are available for breakers up to 1600A in the fixed version.
 
Low voltage moulded case circuit breaker

A moulded-case circuit breaker (MCCB) is a circuit breaker that uses a moulded case to house and support its current-carrying components as well as to be a part of the insulation system.
 
Moulded Case Circuit Breaker or MCCB is an automatic electrical device. It is a type of circuit breaker that protects the circuit from overloading, short circuit and current surges. It is an advanced version of miniature circuit breaker MCB since it operates like one. However, it offers extra features that make it a superior circuit breaker such as remote closing and adjustable trip settings i.e. its current settings and time settings can be adjusted according to our needs.
 
ABB SACE FORMULA DSA circuit breakers are commonly used in commercial and residential applications.
 
The new SACE FORMULA DSP family consists of four frames (P1, P2, P3 and P4) reaching up to 160A, 250A, 630A and 800A respectively. The four frames are available with thermal-magnetic trip units to cover the most common AC and DC fields. Availability of most requested accessories guarantees the possibility to fulfill the main applications needs.
 
1. Compact and competitive
Extremely compact dimensions and coordinated depths mean standardized dimensions and savings in distribution boards design.
 
2. Quality
ABB's long experience in moulded-case circuit breakers design is a guarantee of quality.
 
Application

In order to help with installation of products in switchboard, ABB has developed a dedicated distribution system:
FORMULA Link – Busbars are dimensioned to carry up to 800A. A selection of different frames is available according to the number of breakers installed on the load side.
 
The connection between the supply side circuit-breaker and FORMULA Link is made using a special incoming connections kit, whereas the connection between the load side circuit-breakers and FORMULA Link is made using the outgoing connection kits. Installation and putting into service are simple and rapid. There are different frames of FORMULA Link available:
-250A FORMULA Link
-400A FORMULA Link
-630/800A FORMULA Link.
 
All the versions of the moulded-case circuit breakers can be installed in the FORMULA Link.
 
Durga Mechatronics Pvt Ltd, Mumbai. 
www.durgamechatronics.com