What are the Types of MCB Circuit Breaker?


Based on tripping quality/breaking capacity, MCB( Miniature Circuit Breaker) can be of different types. Today we will discuss types of MCB circuit breaker.

What is tripping quality/breaking capacity? 

We can compare this topic with the human body. We know, human blood is a buffer solution. It means, if you eat acidic and alkaline food together there will be no effect. It will stay neutral.

But if you direct drink sulphuric acid then death is a must. Blood can absorb acid or alkane at a certain level. The same goes for circuit breakers. The circuit breaker can prevent the arch from a certain level of current flow.

If the current flows high than a certain level the circuit breaker will burn automatically. This fixed capacity to prevent arch is the breaking capacity of a circuit breaker. Its unit of measurement is KA (kiloampere).

Now we will discuss different types or categories of MCB / Types of MCB circuit breaker

types of mcb circuit breaker
Breaking Capacity of Circuit Breaker and Human Body

There are 6 types of MCB circuit breaker.

A Type MCB

  • It is a highly sensitive circuit breaker. 
  • Usually, this type of breaker is used in sensitive devices.
  • It can trip double/triple the rated current of the connected device.

B Type MCB

  • This type of circuit breaker device has the ability to trip 3 to 5 times of rated current if a short circuit fault arises.
  • Its operating system is 0.04 to 13 seconds.

For Which Type of Loads It is Used for?

For resistive loads like lightning circuits used in households.

Type C MCB

  • This type of circuit breaker has a breaking capacity of 5-10 times of loads rated current.
  • Its operating time is 0.04 to 5 seconds.

Where It is Used?

Generally, this type of circuit breaker is used for industry’s inductive loads like a transformer, motor, and fan. It means the loads which have the tendency of rush current.

Type D MCB

  • This type of circuit breaker has 10-20 times the breaking capacity of loads’ main current.
  • Its operating time is 0.04 to 3 seconds.

Practical Field

Usually, a D-type MCB breaker is used for high-power industrial loads like welding machines, x-ray.

Type K MCB

  • It has 8-12 times the breaking capacity of the main load current.
  • The operating time is less than 0.1 seconds.

Practical Field

It is suitable for loads that have a tendency of inrush current flow.

Type Z MCB

  • It has a breaking quality of 2-3 times of main load current.
  • Operating is less than 0.1 seconds.

Comparatively which circuit breaker is better?

A, K, Z breaker is comparatively better to use. Because they have less operating time than others. And less operating time means the ability to fast tripping.

Why do we lock the circuit breakers?

Usually for security purposes while any special work in a substation. And the person who locked the circuit breaker has to write his name on the card with the breaker. This card is not flammable. If any accident occurs, the responsible person can be found easily.

circuit breaker locking
Circuit Breaker Locking

That’s all for today’s article ‘what are the types of MCB circuit breaker?’

Hope it was helpful for you to understand the types of MCB circuit breaker.

You can also read: Why My Circuit Breaker is Tripping?