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Important Role of a Circuit Breaker

4/28/2015 1:52:47 PM | by Yumi

Circuit Breakers

A circuit breaker is a significant switch needed in any electrically related works. It is an automatically operated electrical switch that serves as a major defense of an electrical circuit from unexpected destruction caused by overload or short circuit by detecting such current flow interruption.

A circuit breaker fulfills the following functions such as the motor protection, protection of installations and protection of connecting leads. It also perform the signalization of the switching state, tripping indication, remote switching, and switching under normal service conditions. The circuit breaker has the ability to energize and de-energize a circuit. It can be reset manually or automatically to resume its normal operation.

Circuit Breakers can be commercial circuit breakers or residential circuit breakers which vary in sizes in protecting individual appliances or equipment inside your home, offices, and other industrial facilities. It is constructed with five major components; frame (molded case), contacts, arc chute assembly, operating mechanism, and the trip unit. The frame is the insulated housing where breaker components are being mounted. It is usually made of thermal set plastic which determine the interruption rating of the circuit breaker. The circuit breaker usually uses a straight through contact which is being separated and interrupts the current when a fault current is detected. A new contact type called the blow-apart contact design is also used for higher interrupting ratings. Contacts are usually made of copper alloys, silver alloys, and other highly conductive materials. Its service life depends on the erosion of contact material due to arcing. The arc chute assembly is use to quench an arc which can damage the contacts. The arc ionizes gases inside the frame which cause the molded case to rupture. The operating mechanism has a quick-make and quick break design used to connect the operating handle and the moveable contact arm. The trip unit indicates when the contacts will open automatically. It includes elements that can sense heat and high current that may lead to a short circuit or an overload condition. It also includes the trip mechanism which remains locked as long as the tripper bar holds it. When the trip is activated, the trip mechanism releases the operating mechanism which opens the contacts and finally interrupts the circuit. The contacts will be closed again to restore power once the fault condition has been cleared.

Types of Electrical Circuit Breaker

According to arc quenching media
• Oil Circuit Breaker
It is a high voltage circuit breaker wherein the arc is drawn in oil to dissipate heat. The heat of the arc decomposes the oil which generates a gas with high pressure to produce a flow of fresh fluid through the arc which supplies the necessary insulation.

• Air Circuit Breaker
The Air Circuit Breaker interrupts arcing by creating an arc voltage in excess of the supply voltage. It increases the arc voltage in ways such as cooling the arc plasma, lengthening the arc path, and splitting up the arc into a number of series arcs.

• SF6 Circuit Breaker
It is a circuit breaker where the current carrying contacts operate in SF6 gas also known as Sulphur Hexafluoride.

• Vacuum Circuit Breaker
This is a kind of circuit breaker where the arc quenching takes place in a vacuum. It is suitable for medium voltage application.

According to services
• Outdoor Circuit Breaker
• Indoor Breaker

According to the operating mechanism
• Spring Operated Circuit Breaker
• Pneumatic Circuit Breaker
• Hydraulic Circuit Breaker

According to voltage level of installation
• Low Voltage Circuit Breaker
• Medium Voltage Circuit Breaker
• High Voltage Circuit Breaker

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