(MCB) Miniature Circuit Breaker – Construction, Working, Types and Application


MCB (Miniature circuit breaker), an electrical switch is utilized to intrude on the circuit under issue conditions like over-burden and short out. The miniature circuit breakers have been used in many gadgets like computers, TV sets, washing machines, mobile phones, etc. These are small-sized devices that have a low size and lightweight, which is suitable for handling smaller circuits than older models, such as LED lights, power banks, etc. These miniature circuit breakers are also used in automobiles and other small electric appliances. They have smaller components and the compact structure of these units make them suitable for some applications. Besides the usage of the miniature circuit breakers, they can be used to provide more power or heat, and so on.

For those needing reliable electrical repairs or maintenance that ensures your MCB installations meet the highest safety standards, find Sarkinen Electrical for expert services and support.

In this article, we review these tiny devices, their working, types, and applications.

Types of Miniature Circuit Breaker

These days, there are three types of miniaturized circuit breakers, namely single

Transistor miniaturized circuit breakers, double gate transistors miniaturized circuit

Breakers, and multi-gate, two-gate, and multiple-gate miniaturized circuit breakers. A lot of models are available in the market, each with a unique name. When it comes to

Choosing a model, one thing is clear, and that is the cost factor. Generally speaking,

Miniaturized circuit breakers are cheaper than bulky mechanical models and some may

Even cost cheaper.

The working principle of MCB

At whatever time continuous overcurrent passes through MCB, the bimetallic strip is warmed and redirects by bowing. This redirection of the bi-metallic strip delivers a mechanical hook As this mechanical lock is connected with the working component, it causes to open the Miniature circuit breaker contacts, and the MCB switches off accordingly halting the flow to stream in the circuit. To resume the progression of current the MCB must be physically turned ON. This component safeguards from the issues emerging due to overcurrent or over-burden and short circuits. But during short circuit conditions, the current increases unexpectedly, affecting electromechanical removal of the plunger associated with a tripping coil or solenoid. The plunger raids the trip knob triggering the instant release of the latch mechanism and subsequently opens the circuit breaker contacts. This was an easy description of a miniature circuit breaker working principle.

MCB is just easier to replace. The trip unit is the essential part, liable for its appropriate working. There are two key forms of trip mechanisms. A bi-metal offers defense against overload current and an electromagnet offers defense against electric short-circuit current.

Construction of MCB

An MCB typifies a total nook in a formed protecting material. This gives areas of strength for precisely protected lodging.

The exchanging framework comprises a fixed and a moving contact to which approaching and it is associated with outgo wires. The metal or current conveying parts are comprised of electrolytic copper or silver amalgam relying upon the rating of the electrical switch.

As the contacts are isolated in case of an over-burden or short-out circumstance, an electric circular segment is framed. All advanced MCBs are intended to deal with bend interference processes where circular segment energy extraction and its cooling are given by metallic curve splitter plates.

These plates are stood firm on a legitimate footing by a protecting material. Likewise, a curve sprinter is given to drive the bend that is created between the primary contacts.

The working component comprises both attractive stumbling and warm stumbling game plans.

The attractive stumbling plan comprises a composite attractive framework that has a spring stacked dashpot with an attractive slug in a silicon liquid, and an ordinary attractive outing. A current conveying loop in the outing game plan moves the slug against spring towards a proper post piece. So the attractive force is created on the excursion switch when there is an adequate attractive field delivered by the curl.

MCB Applications

MCB performs many capabilities, for example, local control switches, isolating switches against deficiencies, and overload defense devices for setting up or definite types of apparatus or appliances.

MCB is essential for the effective working and upholding the safety of the electric machines. Thus, it finds use in most electrical appliances, be it for household or industrial usage. Most of the electric networks at home like lights, heaters, and fans need MCB to check and protect them.

Preferably, types of MCB are an outstanding solution for homes, buildings, and commercial areas having less equipment. The operative fitting of MCBs can guarantee the safety of all the electrical systems across domestic and industrial use. Here are some kinds of MCB uses:

Domestic Electrical Panels

MCBs defend homes from overload. Because of their capability to deal with a lot of power, they are substantially more dependable and more secure than a circuit. One of its benefits is that it guarantees equivalent appropriation of electrical energy across every one of the gadgets. There will be lesser cases of force variances inside the house.

  • Heaters

MCBs are a reliable safety solution if you have fixed heaters in your home or office. With an effective installation of an MCB, you can evade heaters from growing high voltage variations as it pulls a large amount of power from the central supply.

  • Lights
  • Each family has a broad lighting framework. MCBs can assume a critical part in the successful circulation of power across all the lighting frameworks of the house. For example, the activity of glowing lights needs a lot of power when contrasted with lights. Here is where MCBs act the hero. Also, MCBs help in keeping up with the quality and security of lights.

Industrial use

MCBs can offer an impressible security part in restricted scope as well as tremendous extension organizations. Ideally, most of the equipment in adventures expects up to 30 kA of power supply. In such a case, there is a need to change to MCBs from old wires.


In business establishments, sorts of MCB expect a critical part in staying aware of the viability of the applications and foundations by smoothing out its energy stream. They track down the use in lodgings, stores, and bread kitchens.


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