Gas Circuit Breaker(working , Construction, Advantages & Disadvantages) - Electronicsinfos

What is a Gas Circuit Breaker?

    Gas Circuit Breaker(Operating Mechanism , Construction, Advantages & Disadvantages) - Electronicsinfos

    A gas Circuit breaker is a type of circuit breaker in which Sulphur Hexafluoride (SF6) gas is used as an insulating Medium to distinguish the arc. 

    Over the generations, circuit breakers have evolved from Bulk oil circuit breakers, transitioning to air circuit breakers, Gas Circuit Breakers, and finally vacuum circuit breakers in response to the need for improved system performance. 

    The different parts of the gas circuit breaker including

    Parts of the Gas Circuit breaker

    1. Line connection
    2. One-piece epoxy resin enclosure
    3. Moving contact rod
    4. Main Moving contacts
    5. Tungsten alloy arching contacts
    6. linkage system
    7. adsorption catalyst
    8. safety bursting membrane

    Working of Gas circuit breaker

    When there's a fault, a surge of high current flows. This causes an arc to form when the contacts of the circuit breaker separate. To deal with this, SF6 gas or another insulating gas is injected into the arc chamber using a controlled system for handling gases.

    The injected gas quickly absorbs energy from the arc, creating a dense plasma that puts out the arc. Once the fault is fixed and the arc is put out, the circuit breaker's contacts can be closed again. The gas handling system makes sure that the SF6 gas stays at the right pressure levels.

    The operating mechanism involves the following steps
    • Arc Initiation
    • Gas Injection
    • Arc Extinction

    Construction of Interrupter

    There are two types of interrupter W.r.t construction including

    1. Single Pressure puffer Type C.B
    2. Double Pressure puffer type C.B

    Single Pressure puffer Type C.B  

    Single-pressure puffer CB consists of a moving cylinder system that is used to compress the gas. when we need to distinguish the arc the grass is released through the single nozzle. 

    The pressure depends on the Diameter of the nozzle and the speed of the puffer cylinder. The Ratio of P1/p2 becomes 5 times higher in the opening condition.

    Gas Circuit Breaker(working , Construction, Advantages & Disadvantages) - Electronicsinfos

    Double Pressure puffer type C.B

    Double pressure puffer C.B. is a type of gas circuit breaker in which gas is entered from high pressure to low pressure. In this puffer system, we improved the pattern of flow. Double Pressure provides a 1.5 times higher braking capacity as compared to a single flow. 

    In a double flow, the gas flows in a closed circuit. we use an auxiliary tank in which the gas pressure is filled up to 14 kg/cm². 

    Gas Circuit Breaker(working , Construction, Advantages & Disadvantages) - Electronicsinfos

    There are different parts of the Double-pressure puffer system is

    Double puffer system parts

    1. Enclosure
    2. Fixed contact holder
    3. Puffer cylinder
    4. Insulating nozzle
    5. Insulating cap
    6. path for normal

    Advantages of Gas circuit breaker

    1. Puffer type Circuit breaker is used in the Extra high voltages.
    2. The physical properties of the gas are good to distinguish the arc.
    3. The gas is chemically stable to avoid fire.
    4. The lifetime of SF6 is long.
    5. The SF6 circuit breaker is noiseless as compared to the air circuit breaker.
    6. SF6 circuit breaker needs less maintenance.
    7. There is no current chopping to interrupt the low-value current.
    8. There are no problem of overvoltages in the C.B.
    9. SF6 Circuit Breaker is Reliable.
    10. The installation is easy.
    11. There is no pollution in the SF6 circuit breaker.

    Disadvantages of Gas circuit breaker

    1. There is no proper sealing in the SF6 Circuit breaker so the chance is available for leakage.
    2. To transfer, control and maintain the quality we need a special arrangement.
    3. An insulating gas of gas Circuit breaker is Expensive.
    4. The double-pressure circuit breaker is expensive and complex in construction.
    5. We need internal maintenance on the circuit breaker to work well.


    Gas circuit breakers provide an efficient arc interruption and high interruption capacity, for circuit protection in high-voltage applications. However, their environmental impact, maintenance requirements, and initial costs should be carefully considered when selecting them for specific electrical systems.

    Frequently Asked Questions – FAQs

    What is a gas circuit breaker (GCB)?

    A gas circuit breaker is an electrical device that uses gas, such as sulfur hexafluoride (SF6), as the arc extinguishing medium to interrupt electrical currents during faults.

    What are the advantages of using a gas circuit breaker?

    Advantages of gas circuit breakers include high interruption capacity, fast arc extinction and suitability for high-voltage applications.

    What gases are commonly used in gas circuit breakers?

    SF6 gas is the most commonly used gas in gas circuit breakers due to its excellent arc extinguishing properties and high dielectric strength.

    What are the applications of gas circuit breakers?

    Gas circuit breakers are commonly used in high-voltage applications such as substations, industrial plants, power generation facilities, and electrical grids for reliable arc interruption.

    What is the basic function of a gas circuit breaker?

    The basic function of a gas circuit breaker is to interrupt electrical currents and extinguish arcs during faults.

    Why do we use SF6 gas in the circuit breaker?

    SF6 gas is used in circuit breakers due to its high dielectric strength, arc extinguishing properties, insulation performance and chemical stability.

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