In a power system mechanism, switchgear performs a prominent role as switching, controlling, and protecting the electrical circuits. Out of them, the circuit breaker is one of the switchgear devices.
The circuit breaker has a basic function to provide protection for an electric system such as in generating power plants, transmission and distribution lines, distributors, lighting circuits, etc.
In this tutorial, we will learn the basics of circuit breaker and their types.
What is a circuit breaker?
The basic definition of the circuit breaker:
The elecctrical device which has the capability to protect the circuit under the occurrence of the fault and to clear the fault condition is called a ‘Circuit Breaker’.
Sometimes, the circuit breaker (CB) works as an auto-switch protective device. It has the tendency to break and make circuits under all fault conditions (like no-load, full-load, and short-circuit).
It can be easily operated with the following conditions.
- Under the normal condition, the circuit breaker can open or close the circuit by the manual or remote control.
- Under the fault or abnormal condition, the circuit breaker automatically open the circuit. And it can close (or make) the circuit by the manual or remote control.
Thus, it is very useful equipment to switch the various parts of the power system. And it can carry very large currents and serve very high voltages as compared to the other devices (like a fuse).
It is rated in terms of maximum current carrying capacity, maximum voltage, number of poles, frequency, maximum interrupting capacity, etc.
There are different types of circuit breakers that are used for circuit switching mechanisms under the low tension (LT) and high tension (HT).
Let’s study, multiple types of the circuit breaker.
What are the types of circuit breaker?
What is the classification of circuit breakers based on different criteria?
Based on the high tension:
Under the power system protection, the circuit breaker is classified in different ways. Based on arc extinction or quenching medium, it is mainly divided into five main parts.
- Air circuit breaker
- Air blast circuit breaker
- Oil circuit breaker
- Vacuum circuit breaker
- Sulphur Hexafluoride circuit breaker
For the arc extinction, air or oil or sulphur hexafluoride gas or compressed air mediums are used in circuit breakers.
Let’s study each circuit breaker one by one.
1. Air Circuit Breaker
An air circuit breaker (ACB) is designed for low and medium-voltage protections. Compressed air or gas works as a circuit-breaking medium, in an air circuit breaker.
This circuit breaker is used in lighting systems, distribution systems, and motor circuits. It can be used in AC circuits or DC circuits for maintaining indoor applications.
2. Air Blast Circuit Breaker
The air-blast circuit breaker is needed for interrupting current at high-pressure or high voltage installations.
In this circuit breaker, high pressure (or other gases such as hydrogen, nitrogen, and carbon dioxide) is used as the arc quenching medium.
Along the arc path, the air blast circuit breaker is classified into three categories.
- Axial air-blast circuit breaker
- Cross air-blast circuit breaker
- Radial air-blast circuit breaker
Generally, it is mostly used in industrial plants, especially for the main power distribution and transmission.
3. Oil Circuit Breaker
For the oil circuit breaker, insulating types of oil (like transformer oil) are used as an arc quenching medium.
It is the oldest type of circuit breaker which has more functions like good reliability, simplicity of construction, and relative cheapness.
This circuit breaker is mainly classified into two parts.
- Bulk oil circuit breaker (BOCB)
– Plain break oil circuit breaker
– Self generated pressure oil circuit breaker
– Impulse oil circuit breaker
- Low oil circuit breaker (MOCB)
4. Vacuum Circuit Breaker
A vacuum circuit breaker (VCB) is a very simple construction as compared to air and oil circuit breakers. In this circuit breaker, vacuum offers a high insulating strength in the range from 10-7 to 10-5 torr.
As per construction, it is classified into two parts.
- Fixed type vaccum circuit breaker
- Moving type vaccum circuit breaker
VCB is used for medium-voltage ratings (like 11KV and 33KV). It is widely used for the substation for the overload or high current protection.
And it is used for transformer switching, reactor switching, capacitor bank switching, etc.
5. Sulfur Hexafluoride Circuit Breaker
Sulfur hexafluoride (SF6) gas is used as an arc quenching medium, instead of oil, air, or a vacuum. It serves high voltage and extra-high voltage.
Based on the working principles, the SF6 circuit breaker is commonly divided into three types.
- Single puffer piston circuit breaker
- Double puffer piston circuit breaker
- Non puffer piston circuit breaker
The SF6 circuit breaker is widely used in electrical grids, power stations, transmission, and distribution systems.
These are the high voltage breakers that protect and control the electrical power transmission networks.
Other Classification of Circuit Breaker
Based on the low tension:
- Miniature circuit breaker (MCB)
- Molded case circuit breaker (MCCB)
- Solid-state (Digital) circuit breaker
- Residual current circuit breaker (RCCB)
- Earth leakage circuit breaker (ELCB)
These are the top 10 different types of circuit breakers that are used for switching or tripping mechanisms in abnormal conditions. This mechanism requires less working time (near about 30 ms and 150 ms).
Several types of circuit breakers are found as per their specifications and different brands. And each type of circuit breaker has its own advantages and disadvantages.
In an upcoming article, I will briefly explain all low tension (LT) circuit breakers with their working principle, construction, and other specifications.
If you are working or using any circuit breaker, let me know in the comment section below.
Read more related articles:
- Miniature circuit breaker vs Molded case circuit breaker
- Fuse vs Circuit breaker
- Substation components
- Overhead lines components
- Insulating materials & insulation classes
- Single phase vs Three phase AC system
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