Guide To Vacuum Circuit Breaker Construction And Working

This Article Discusses an Overview of What is a Vacuum Circuit…

This Article Discusses an Overview of What is a Vacuum Circuit Breaker, And Vacuum Circuit Breaker Construction And Working

What is a Vacuum Circuit Breaker?

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A vacuum circuit breaker is a type of circuit breaker in which the arc extinguishing is done in a vacuum environment.

The process of switching on and off of current-bearing contacts and related arc interruption takes place in a vacuum chamber located within the breaker, known as a vacuum interrupter.

A vacuum that is used as the arc quenching medium in a circuit breaker is known as a vacuum circuit breaker because vacuum gives high insulating strength due to superior arc quenching properties.

This is suitable for most standard voltage applications because, for higher voltage, vacuum technology was developed however not commercially feasible.

The operation of a current-bearing connection and the related arc interruption occur in an airless chamber inside the breaker, referred to as a vacuum interrupter. This interrupter contains a steel arc chamber situated in the middle of two symmetrically placed ceramic insulators. The preservation of vacuum pressure inside a vacuum interrupter can be kept at 10– 6 bar. The effectiveness of the vacuum circuit breaker mostly depends on the materials utilized for current-transporting contacts like Cu/Cr.

How do Electrical Vacuum Circuit Breakers Works?

A vacuum circuit breaker (VCB) is a device that uses the working principle of a vacuum for switching and interrupting electrical power circuits.

It has been in use for over five decades and is now considered to be one of the most reliable circuit breakers available on the market today.

The main component of an VCB is a metal vapor arc chamber, where the vaporization of metal vapor occurs when an arc is created between two contacts. This causes ionization, which results in increased dielectric strength.

40.5kv vacuum circuit breaker

A vacuum circuit breaker depends on this high dielectric strength and low ion density to ensure proper operation. When current flows through the arc, it creates a metallic plasma that helps extinguish the arc by cooling it down, increasing its resistance and finally breaking it apart. Vacuum circuit breakers are used in industrial settings due to their ability to withstand high voltage fluctuations without damage or interruption of electricity supply.

Principle of Vacuum Circuit Breaker

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A vacuum circuit breaker is a device which utilizes the principle of vacuum to interrupt the circuit and stop the flow of electricity.

It works on the principle of high dielectric strength to restrict the arc that forms while opening or closing an electrical circuit.

The contacts of the breaker are made up of metallic material, creating a gap between them when separated. This gap is filled with vacuum (vacuum in torr) to ensure insulation and prevent any electric arc from forming.

When current passes through, it can ionize the gas present within, therefore vaporizing some metal particles which form a metal vapor cloud around it and acts as an arc shield.

This arc shield helps in quenching or extinguishing the arc quickly and reduces damage to fixed and moving contacts of the breaker. Vacuum also helps in maintaining longer contact life by providing more insulation than air, thereby allowing fewer electrons to pass through and helping reduce wear on circuit breaker contacts.

Construction of Vacuum Circuit Breaker

The construction of a vacuum circuit breaker is based on an insulated moving contact, which is connected to a bellow, supported by metallic components and enclosed in a vacuum chamber.

The chamber is sealed to prevent vapor from entering the atmosphere and creating an arc shield. This allows for interruption of high voltage currents in a very short time. To ensure good performance of the vcb, stainless steel materials are used to provide optimal insulation and protection against corrosion.

The fixed contact point must be able to withstand high voltage levels without any damage or deformation, while the moving contact point needs to be able to move freely in order to make contact with the fixed contact point during operation.

construction of vacuum circuit breaker

When the circuit breaker is opened, an arc will form and it will be extinguished due to lack of oxygen inside the chamber. This ensures safe operation at all times and prevents any electrical fires from occurring as a result of interruption issues.

Working of Vacuum Circuit Breaker

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When two contacts part ways due to an irregular situation, a spark is created between them, caused by the electrification of metal particles and dependent on the substance of the contacts.

The arc diffusion in vacuum interrupters is distinct from other forms of circuit breakers. Isolation of the link leads to the light dissipating, thereby filling in the contact point. Positive ions are detached from the connection material. The steam concentration relies on the arc current; as the current declines, so does the speed of light vaporization.

After the current zero, if the vapor density is low the medium regains its dielectric strength. When the constrained current is very small in a vacuum, there are many parallel paths to the arc.

Total currents are divided into several parallel arcs. Which repel each other and spread to the contact surface. This is called a scattered arc that can be easily disrupted.

Concentrated in a small area of ​​the arc at a high value of current causes rapid evaporation of the contact surface. Disruption of the arc is possible if the arc is in a scattered state. If it is quickly removed from the contact surface, the arc will strike again.

Arc destruction in a vacuum breaker is greatly influenced by the material of the contact and the technique of considering the metal vapor. The path of the arc is changed so that the temperature does not rise at any stage.

After the final arc disruption, there is a rapid building of dielectric strength which is fantastic for a vacuum breaker. They are perfect for switching capacitors. Because it will perform re-strike-free. The small current is interrupted before the natural current zero, which can cause it to cut which level depends on the contact material.

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