Miniature circuit breaker

To ensure the safety and management of the system, all fuses should be replaced with MCB “Miniature Circuit Breaker.” An MCB, unlike a fuse, is an automated switch that opens in the event of excessive current flowing through the circuit and can be reclosed without the need for manual replacement. Most circuits employ MCBs as a replacement for the fuse switch. To ensure safety in residential, commercial and industrial settings, many different types of MCBs with breaking capacities ranging from 10 kA to 16 kA are in use. A Miniature Circuit Breaker (MCB) is an electrical switch that automatically shuts off power to low-voltage circuits if an overload or short circuit causes too much current to flow through them. Thermal or thermal-magnetic MCBs typically have current ratings of 125 A and do not have customizable trip characteristics.

Miniature circuit breaker (MCB) 

Overcurrent protection in electrical circuits is provided by MCBs, which are electromechanical devices. A short circuit or overload could be the first cause of an overcurrent. Fuse-like MCBs do not need to be replaced every time a fault occurs; instead, MCBs can be reused. In addition, operational safety has been increased without incurring a substantial operating expense.

Fuse 

The complete fuse wire must be changed in order to fix a blown fuse.  A fuse is an electrical safety component in electronics and electrical circuits that acts as an overcurrent protector. Metal wire or strip that melts when too much electricity travels through it is its primary component. When the fuse blows, the circuit is broken and must be replaced or rewired, depending on the type of fuse.

Advantages of MCB over the fuse 

• When it comes to switching between circuit breakers, the MCB has numerous distinct advantages.
• When it comes to current, MCBs are more sensitive than fuses
• When it senses an anomaly in the flow of current, it shuts down the electrical circuit automatically.
• In the case of an MCB, it is simple to locate the area of the circuit that is defective.
• Faulty circuitry causes the device to shut down. While it is possible to determine the exact location of the problem with a defective Fuse by opening the fuse grasp, this is not always possible.
• Resuming supply is a breeze when using MCB.
• You only need to turn the MCB back on by turning the knob to the On position. But in case of a fuse, the entire fuse wire needs to be changed.
• Handling an MCB is safer than a Fuse in terms of electrical shock.
•  If you have an MCB, It’s possible to come into contact with a live wire / current-carrying conductor while replacing the Fuse, however, an MCB does not expose the operator to live electrical components.
• Because MCBs are reusable, they require minimal upkeep and replacement.
• In contrast, when a fuse blows, it necessitates a replacement.

Working principle of miniature circuit breaker 

The bimetallic strip heats up and bends when an overcurrent travels through an MCB. A mechanical latch is released as a result of the deflection of the bi-metallic strip. To prevent current from flowing, the mechanical latch is coupled to an operational mechanism that causes the small circuit breaker contacts to be opened, and the MCB is turned off. The MCB must be manually turned ON in order to restore normal current flow. Overcurrent, overload and short circuit problems are protected by this method. However, when a short circuit occurs, the current increases rapidly, forcing the plunger connected with a tripping coil or solenoid to be electromechanically displaced. The latch mechanism is immediately released, allowing the circuit breaker contacts to open. This was a straightforward explanation of how a little circuit breaker works. It’s not common practice to repair an MCB, despite the fact that it’s a basic device. It’s just a lot easier to get rid of. To ensure that the device functions properly, it must have a trip unit at its core. Trip mechanisms can be divided into two main categories. A bi-metal and an electromagnet guard against overcurrent and short-circuit current, respectively.

How to operate MCB

Bi-metal strip deforms if the circuit is overloaded over a long period of time The latch point is shifted as a result of the Bi-metal strip deformation. For the MCB to open, a small displacement of the latch causes the spring to release and cause the moving contact to move. This is accomplished by the use of spring pressure and the latch point.

When a short circuit fault occurs, the magneto-motive force (MMF) of the current coil or trip coil is applied to the coil, causing its plunger to strike the same latch point and displace the latch. There are two ways to manually turn off an electrical circuit breaker: You can press the reset button on your mini-circuit breaker or you can use your hand to turn it off. Both methods have their advantages and disadvantages.

The same latch point is relocated and the same deformed spring is released for a variety of reasons, including deformation of a bi-metallic strip, increased mmf from a trip coil or even a manual operation. When the moving contact separates from the stationary contact, there is a substantial probability of an arc developing. The arc is finally quenched after ascending through the arc runner and entering arc splitters. It is ready for another switch-off or trip action as soon as it has been returned to its original position by turning it on.

Conclusion 

A Miniature Circuit Breaker (MCB) is an electrical switch that automatically shuts off power to low-voltage circuits if an overload or short circuit causes too much current to flow through them. Thermal or thermal-magnetic MCBs typically have current ratings of 125 A and do not have customizable trip characteristics. MCBs are reusable and require minimal upkeep and replacement. Overcurrent, overload and short circuit problems are protected by this method. MCB must be manually turned ON in order to restore normal current flow.

It’s not common practice to repair an MCB, despite the fact that it’s a basic device. Trip mechanisms can be switched on or switched off manually. The same latch point is relocated and the same deformed spring is released for a variety of reasons. When the moving contact separates from the stationary contact, there is a substantial probability of an arc developing.