Rated current: This is the maximum values of current the breaker can withstand without tripping. When selecting your desired miniature CB, the following things should be put into consideration. This is the value of current an MCB can contain without tripping. They are used in places with an unbalanced circuit. But unlike the three poles with neutral, the four poles protect all the phases and the neutral. It also has a neutral switch.Ī four-pole MCB contains four switches, three phases, and a neutral. Three poles and a neutral circuit breaker protect the three phases of the circuit. The double pole MCB has two switches and also protects two-phase and neutral.Ī three-pole circuit breaker has 3 switches, and they also protect the three phases. We have:Ī single-pole circuit breaker has one switch and also protects a single phase of the circuit. Bi-metallic Strip Types of MCBs based on the number of polesĪnother way of classifying MCBs is on the number of poles they have. They are sensitive to short circuits and are suitable for protecting sensitive devices such as semiconductor devices. This MCB trips when the current is 2 to 3 times above the current rating. They are suitable for inductive and motor loads with high inrush currents. This type of MCB trip when the current is 10 to 12 times above the current rating. For example X-ray machines, winding motors, big transformers, etc. They are used in big industries where the inrush current is high. This circuit breaker trips when the current is 10 to 20 times higher than the current rating. Items they protect include transformers, fluorescent servers, printers, and pcs. 
They are used in commercial industries where there may be greater chances of short circuits and overloads. This type of MCB trip when the current is 5 to 10 times higher than the current rating. They are used in residential appliances and in some commercial applications where the surge current is low. This circuit breaker trips when the current is 3 to 5 times above the current rating. Their various types are Type B, C, D, K, and Z. The trip curve is the highest current an MCB can withstand before tripping off. But before that, let us know the meaning of a trip curve. There are several types of MCB switches based on their trip curves. Types of MCBs according to their trip curves. Whenever there is a circuit overload, the switchgear trips. The thermal operation of an MCB works with the help of the bimetallic strip. This causes the tripping plunger to shift, leading to the release of the latch mechanism that opens the contact. Whenever a short circuit occurs, a heavy current flows through the solenoids. Under the working conditions of the circuit breaker, current flows from the incoming terminal to the fixed and moving contacts, solenoid, a bimetallic strip, and then to the outgoing terminals.
Thermal operation for overload protection. An electromagnetic operation for short circuit protection. They do that via two operational methods. Like molded case circuit breakers, MCBs protect electrical systems from overload and short circuits. Note: MCB cannot protect you from electric shock, an RCD or GFCI does that. 
MCBs are easy to restart after tripping while fuse must be changed.Unlike a fuse, MCB has a plastic enclosure that covers the metallic conductor.MCB last for a long time, while fuse gets damaged after a single trip.6.3 What is the difference between MCBs and MCCBs? Why you should choose an MCB switch over fuse
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