What is a Circuit Breaker: Types and Applications

A circuit can be damaged which will reduce its reliability. Therefore, electrical circuits need to be protected using circuit protection devices. Usually  fuses, chokes, decoupling capacitors, zener diodes, protection diodes are enough to prevent the electronics from any mishap. Circuit breakers are also used for the same purpose in electrical systems. A circuit breaker can be defined as a type of switching device that prevents damage to the electrical system by acting as a switch and that interrupts the current flow. This article will take a closer look at circuit breakers along with various types, we will study their advantages and disadvantages, examine their operational principles, and more. Know more about electronics and PCB through our interesting blog writings.

What is a Circuit Breaker?

A circuit breaker is a switching mechanism that may be operated either manually or automatically to cut off the flow of electricity when it detects an abnormal current or fault in an electrical circuit, therefore reducing the overloading and short circuit situations.

Circuit Breakers serve the same function as fuses but unlike fuses they are not destroyed/burned when activated or triggered . Unlike fuses, we do not need to replace them and can simply be reset once the fault has been recognized. When an overload occurs, a circuit breaker will open the circuit to prevent any type of harm . They contain a switch to return to the closed position once they have been flipped. Circuit breakers are often employed in household,  industrial, and commercial electrical setups so as to protect items from harm.

How to Choose a Circuit Breaker:

To choose a circuit breaker, you need to understand its specifications. The major factors you should consider are:

Voltage rating: The voltage rating is the highest possible voltage that can be applied across the circuit breaker. It’s important to understand how much voltage your intended application requires and choose a circuit breaker with a voltage capacity that can handle it.

Continuous current rating: To know the continuous current rating, identify the amperes. The ampere rating tells you how much continuous current a circuit breaker can take without overheating.

Frequency: To determine the frequency your circuit breaker can handle, consider the amps. For example, circuit breakers of 600 amps are capable of handling frequencies of 50 to 120 Hertz. Choosing the wrong one can result in lost energy and increased heat, reducing efficiency and potentially damaging components.

Max interrupting capacity: A circuit breaker’s max interrupting capacity must always be higher or equal to the fault current that triggers the breaker to open. Otherwise, the circuit breaker could be damaged.

Circuit Breaker Design:

Now, to understand how a circuit breaker works, let’s first take a look at a cross-section of the device that shows the basic parts and design of a circuit breaker. The basic circuit breaker consists of:

1) A terminal

2) A stationary contact

3) A catch

4) A simple switch

5) An electromagnet (copper coil)

6) A bimetallic strip

7) Another terminal

Types of Circuit Breakers:

There are mainly four types of Circuit breakers:

• Air Circuit Breaker
• Vacuum Circuit Breaker
• Oil Circuit Breaker
• SF6 Circuit Breaker

Working Principle of Circuit Breaker:

A circuit breaker has mainly 2 contacts :

1. A moving contact

2. A fixed contact

Normally, the contacts are closed, thus allowing current to pass throughout the circuit. A mechanism that releases accumulated potential energy separates the contacts in case of any  overload or short circuit. That mechanism may be magnetic, pneumatic, hydraulic, or spring-operated.

An arc, which is  strongly ionized and conducts plasma, is formed when contacts are  separated. The arc can damage the contacts and the surrounding equipment if not extinguished quickly. Therefore, various methods like cooling, compressing, or replacing the ionized medium with fresh gas are used to quench the arc in circuit breakers. The voltage level and current rating of the circuit breaker determine the appropriate arc quenching medium to utilize.

In a broader sense a circuit breaker mainly interrupts the flow of electricity by rapidly opening the circuit to identify a defect and monitoring the current in a circuit. Combining thermal and magnetic principles enables a dependable reaction to different kinds of failures, guarding against short circuits and over currents.

Circuit Breaker Tripping Principles:

This circuit breaker contains two different tripping principles to protect the circuit:

• A thermal protection design that will lead to circuit interruption in case of overheating
• A protection design via an electromagnet principle, due to a short circuit.

1) Thermal protection

On this thermal-magnetic circuit breaker, both thermal and electromagnetic protection happens in parallel on a similar principle to move the switching linkage. If the circuit’s current rises over a certain level, the strip will bend, moving the switch linkage, and consequently the moving contact, breaking its connection to the stationary contact, causing the circuit to break.

2) Short circuit protection

In parallel, electromagnetic protection comes from the copper coil. The electromagnet is magnetized when electricity flows through the terminals. The larger the current, the larger the electromagnetic force. When a current reaches unsafe levels while traveling through this coil, the electromagnet becomes strong enough to move a small spool inside it, which will also move the switch linkage, the moving contact, therefore breaking the circuit.

Miniature Circuit Breakers (MCBs):

These are the most common types found in homes. They protect your electrical circuits from overloads and short circuits. MCBs are equipped with two tripping mechanisms: the delayed thermal tripping mechanism for overload protection and the magnetic tripping mechanism for short circuit protection.

Advantages and Disadvantages of a Circuit Breaker:

Some of the Advantages and Disadvantages of a Circuit Breaker are given Below:

Conclusion:

Circuit breakers act as the essential safety devices that interrupt/stop the flow of current in case of overload or faults. Their innovation has revolutionized the electrical systems, offering protection against damage, fire hazards, and even enhancing efficiency. As the technology evolves, circuit breakers continue to adapt, remaining indispensable in safeguarding our modern-day electrical infrastructure.