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Classification of Circuit Breaker | Types of Miniature Circuit Breakers (MCB)

 Learn more about Classification of Circuit Breaker and types of miniature circuit breakers. MCBs designed to protect electrical circuit and devices. It also known automatically operated electrical switch. Main use of the breakers, protect our device from more damage due to an overload or short circuit. Miniature circuit breakers are an automated fuse in branch circuits.


Classification of Circuit Breaker | Types of Miniature Circuit Breakers (MCB)
MCB selection


There are different curves circuit breakers available in A, B, C, D, K and Z.

To protect from overload, the protective device must be selected based on current carrying capacity.

Typically, the MCB type indicates current limitations at the time that the circuit breaker is tripping instantaneously. When choosing the type of circuit breakers, it is therefore important to consider the maximum current during normal operation of the equipment.

In simple words to say, for the beginning current of equipment has to calculate and select the type of circuit breaker equipment. So the inrush current of the device can be turned on without tripping the MCB. But it is not more than the running current. Let see how to select type and uses of miniature circuit breaker.

Type-A Circuit Breaker

MCBs in the A type are highly sensitive devices that trips instantly when the current reaches 2 to 3 times the rated current. They have primarily been used to protect highly sensitive devices. This breaking time is 0.04 to 1 seconds of trip time.

These are like Class Z MCBs, it also (type A) highly sensitive to short circuit, used for the semiconductor devices protection.

E.g. If a 10 Amps A curve MCB,  when passing over current that 2 to 3 times (20 to 30 Amps) the device quickly tripping in a 0.01 to 1 Sec.



Type B Circuit Breaker

'B' type MCB is the minimum tripping current: 3 to 5 times of the rated current.

Type of 'B' miniature circuit breaker (MCB) is used with purely resistive loads or very small inductive components. This breaking time is 0.04 to 1 seconds of trip time. They are very common use for home electrical distribution board.

E.g. If a 6 Amps B curve MCB,  when passing over current that 18 to 30 Amps the device quickly triped in a 0.04 to 1 Sec. 

This type MCB triping instantaneously in a very small amps in less than one sec. So they are mostly using in house wiring. 

Heater

Lighting circuit (non-inductive)

General purpose outlet

Type-C, Circuit Breaker

'C' type MCB is the minimum trip current: 5 to 10 times the rated current. These operating times of the device are 0.04 to 5 seconds.

E.g. If a 6 Amps C curve MCB,  when passing 30 to 60 Amps quickly triped in a 0.04 to 5 Sec.


This type of miniature circuit breaker (MCB) is used for loads with a medium inductive component, typically electrical devices that use specific types of light or low-power motors:

Ballasts which use an inductive component with light

Residential or Commercial Use Pump

Air conditioner

Induction fans

Circuit Breakers Type- D

'D' type MCB is the minimum trip current: 10 to 20 times the rated current. These operating times of the device are 0.04 to 3 seconds.

E.g. If a 10 Amps K curve MCB,  when passing 100 to 120 Amps quickly triped in a 0.04 to 3 Sec.

This type of mini circuit breaker (MCB) is used for loads with very high inductive components. Commonly used in industrial power supplies.

Type D - MCB mainly uses in high-power industrial applications such as 

Heavy motors, 

X-rays, 

Transformers, 

Welding machine, etc.

Miniature circuit breaker type-K

Type K mcb is tripping when the current reaches 8 to 12 times that of the rated current with an operating time less than 0.1 sec. This type mcb uses for inductive loads that have a chance of high pressure currents.

E.g. If a 10 Amps K curve MCB,  when passing 80 to 120 Amps quickly triped in a 0.01 Sec.

Miniature Circuit Breaker Type Z

Type 'Z' MCB operate 2 to 3 times the current value of rated current with an operating time of less than 0.01 second.

E.g. If a 10 Amps Z type MCB,  when passing 20 to 30 Amps quickly triped in a 0.01 Sec. 

MCB type ‘Z’ mainly used in, 

Motherboard power supply 

Electronic circuit board 

Highly sensitively devices 


Compared to "B", "C" and "D" MCBs tripping characteristics, "K" and "Z" MCBs provide more protection during operation.

Type A, K and Z MCBs have much shorter operating times than Type B, C and D MCBs. Class A, K and Z are highly sensitive breakers that work very quickly in a short period of time to protect sensitive equipment. 

I think you got knowledge about Classification of Circuit Breaker and types of miniature circuit breakers from our article. Learn more about electrical.

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