Circuit Breaker: Types, Uses, and Applications

Circuit breakers are everywhere. These electrical switches are installed in the power systems of our homes, offices, electric vehicles, and infrastructure to protect us from short circuits or overloads. Many of us don't have any idea what a circuit breaker is, but it is essential to support our daily routines.As the demand for electricity and electrical devices rises, the necessity of circuit breakers also increases. You can order such a circuit breaker from the Lauritz Knudsen (Formerly L&T Switchgear). It ensures the safety and effective distribution of electricity and emphasizes energy efficiency and technical innovation.

In this blog, let us explore what is circuit breaker, the types of circuit breakers, the function of circuit breakers, and its applications.

What is a Circuit Breaker?

A circuit breaker is a switching device created to control or protect electrical power systems when a fault, such as a short circuit or overload, occurs. If you don’t have a circuit breaker, parts of the power system could be damaged, overheated, or catch fire.

To make things clearer, circuit breakers do the same thing as fuses. Fuses are one-time utility devices that should be replaced after overload, whereas circuit breakers can be reset manually or automatically as switches.

How does Circuit Breaker work?

The circuit breaker automatically opens the circuit and cuts off the flow of electricity when an excessive amount of electricity, referred to as fault current, passes through it. Let us understand how a circuit breaker accomplishes this in detail.

1. Fault Detection: The circuit breaker consists of two contacts, one fixed and the other moving. They always physically touch each other, which is called a closed condition that allows the current to flow continuously. Mechanical pressure applied on the moving contact initially puts the circuit breaker in the “ON” state. A switching signal is given if the circuit breaker detects a fault condition, such as a short circuit or overload.
2. Release Potential Energy: The operating mechanism stores potential energy released when the switching signal is provided to the breaker. We can store the potential energy with hydraulic pressure, compressed air, or deforming metal springs. Regardless of the source, potential energy should be released during the operation. After the total energy is released, it should be stored again in the operating mechanism by an air compressor, spring charging motor, or other suitable means.
3. Separate Contacts: The two contacts, a fixed and a moving contact, are in closed conditions opened by the potential energy. The released potential energy separates the two contacts by allowing the moving contact to slide rapidly.
4. Arc Formation: The separation of two contacts creates an arc. It is a highly ionised (electrically charged) and conductive plasma. If not extinguished properly, it can damage the two contacts and other equipment surrounding it and even catch fire.
5. Arc Quenching: The process of extinguishing the arc is called arc quenching. Circuit breakers use various methods to quench arcs, such as replacing the ionised medium, compressing, or cooling. The quenching medium depends on the current rating and voltage level of circuit breakers
6. Interrupt Current: The quenching process stops the current from flowing, preventing component damage or fire.
7. Reset Circuit Breaker: Once the error has been fixed, we can manually or automatically reset the circuit breaker. This restores the current to flow again.
8. Connect Contacts: When the circuit breaker is reset, the two contacts fixed and moving come back to contact each other and allow the current to flow.

What are the Types of Circuit Breakers?

Circuit breakers can be of different types depending on the installation location, quenching medium, voltage level, and operating mechanism.

Installation Location-Based Circuit Breakers:

1. Outdoor Circuit Breaker: These are designed to be fixed on the outside of the building and are made to survive challenging weather conditions.

2. Indoor Circuit Breaker: As the name suggests, indoor circuit breakers are intended for installation inside buildings. They can be run at low and medium voltage levels and are enclosed in a weatherproof material.

Quenching Medium Circuit Breakers:

1. Oil Circuit Breaker: Mineral oil is the quenching medium used in oil circuit breakers, as it has high cooling properties. The contacts are immersed in the oil-filled chamber. When the contacts are open, an arc is formed in the oil. Then, the oil is decomposed into hydrogen gas, reducing the temperature and pressure of the arc. Oil circuit breakers are used in high-voltage areas such as substations.

2. Air Circuit Breaker: Compressed oil is the quenching medium used in air circuit breakers as it has high thermal conductivity. The contacts are enclosed in an airtight chamber connected to an air compressor. When the contacts are open, air bursts into the arc and blows away from them. This cools down the contacts and removes the ionised particles from them.

3. SF6 Circuit Breaker: Sulphur hexafluoride gas is the quenching medium used in SF6 circuit breakers, as it has arc-extinguishing properties. The contacts are placed in a sealed chamber attached to a gas at low pressure. When the contacts are open, the gas flows on the arc, reducing the conductivity and cooling down the contacts. It is used in medium and high voltages.

4. Vacuum Circuit Breaker: Vacuum is the quenching medium used in vacuum circuit breakers. The contacts are enclosed in a metal or ceramic chamber evacuated to a very low pressure. When the contacts are open, an arc is initiated in the vacuum and extinguished.

Voltage Level-Based Circuit Breakers:

1. High Voltage Circuit Breaker
2. Medium Voltage Circuit Breaker
3. Low Voltage Circuit Breaker

Operating Mechanism-Based Circuit Breakers:

1. Spring-Operated Circuit Breaker: Mechanical energy is stored inside the spring, which is locked by a latch. The latch is released when the circuit breaker gets a switching signal, and the mechanical energy opens the contacts.
2. Pneumatic Circuit Breaker: Compressed air opens the contacts. It is stored in a tank. On receiving the switching signal, the air is released to open the contacts.
3. Hydraulic Circuit Breaker: A piston and hydraulic fluid open the contacts.

What are the Uses and Applications of Circuit Breakers?

Electrical circuit breakers have several uses in various fields. It includes,

• Commercial: Circuit breakers protect against faults, overloads, power surges, and other hazards in business premises, including hospitals, malls, hotels, and offices. They also enable automation and energy management.
• Power Generation: Circuit breakers prevent damage to transmission lines from switching surges, lightning strikes, faults, etc. They also permit power system network sectionalisation and load shedding.
• Rails: Faults, overloads, short circuits, and other hazards are guarded against by circuit breakers on rail vehicles, which include trains, trams, metros, etc. They also enable motor regenerative braking and traction control.
• Industrial: Industrial equipment, including pumps, compressors, fans, and so on, is shielded from defects, overloads, phase imbalances, and other hazards by means of electric breakers. They also enable motor soft starting and speed control.
• Power Distribution: Circuit breakers protect feeders, induction motors, distribution transformers, and other equipment against overloads, low voltages, and other problems. Additionally, they provide demand response and load management for power system loads.

What are the Pros and Cons of Circuit Breakers?

Pros:

Circuit breakers have many benefits over fuses.

• It can be used many times without replacement by resetting the switches.
• Manual or automatic switching is possible.
• It can be used for selective protection of different parts of power systems.
• High fault currents are interrupted without any harm.
• It prevents fire hazards.

Cons:

Circuit breakers also have some drawbacks over fuses. It includes,

• The cost of a circuit breaker is high
• It should be regularly maintained for proper functioning.
• It may fail due to mechanical faults.

Read Also: MCB (Miniature Circuit Breakers) Guide - Types, Sizes, And Uses

Conclusion

Circuit breakers are essential for safeguarding electrical and human lives by interrupting abnormal current flow and returning to normal after rectifying the fault. They are of many types based on the quenching medium, operating mechanism, voltage level, and installation location.

You can choose them from our reliable electrical store. Lauritz Knudsen (Formerly L&T Switchgear). We have been active in manufacturing and distributing premium electrical products. Our circuit breakers ensure reliable protection and control of electrical power systems.

Stay safe with Lauritz Knudsen (Formerly L&T Switchgear) range of circuit breakers – protecting your home and office from potential fires and sparks! We have an extensive range of circuit breakers suitable for different purposes. Check out our offerings and choose our products for durability and quality.