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An air break switch is a type of switch that makes use of air as a dielectric and arc quenching medium. The contacts of an air break switch open in the air. Here, the arcing problem produced while opening the switch is resolved with the help of compressed air. These types of switches are generally operated at low voltage levels, i.e., voltage ranging from 450V up to 35kV. The current range of air break switches lies between 800 A and 10KA. The air pressure used by the air break switches ranges from 4 to 60 atmospheres. It can also be said that an air break switch is a switchgear device that makes use of air as an interruption medium.

Working of an Air Break Switch

An air break switch is typically used to open the circuit under the load. The arc that gets produced during the process of opening the switch is quenched in many ways. It can be extinguished by moving the contacts away from each other or by supply interruption. Usually, the arc is put out with the help of lengthening of the arcing horns present in the structure of the switch. These arcing horns are nothing but the pieces of metals between which the arc is formed. As the switch gets opened, the arcs tend to move far from each other, eventually breaking out. The main components of an air break switch include an arc extinguisher, a reservoir provided with a supply of compressed air, and an electro-pneumatic actuator. The arc extinguisher is connected to the compressed air reservoir with the help of an insulated line. It is used to quench the arc produced between the movable and the fixed contacts. The de-energized electromagnet tends to open the air blast valve through a system of various pneumatic devices. This helps supply the compressed air from the reservoir to the arc blowout chamber through the airline. This compressed air tends to act on the piston of the movable contact and separates the movable contact from the fixed contact. The arc that gets formed due to the opening of the contacts of the switch is required to be extinguished. The compressed air from the chamber is used for the purpose of arc quenching. The compressed air is directed through the outlets of the contacts to the gas escape channels. After some time, the air enters the cylinder of a pneumatic actuator and quenches the arc. After the arc extinguishes, the compressed air actuates the piston and breaks the isolating switch contacts. The contacts are closed and the incoming of the compressed air is then cut off. When the electromagnet gets energized, the valve opens and the compressed air is allowed to pass through the insulated airline. The air enters the cylinder, acts on the piston, and closes isolating switch contacts. Some of the air break switches are manufactured with air-filled isolating switches. Such switches consist of contacts that are packed in an insulated casing. The switch gets filled up with compressed air after being disconnected.

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Types of an Air Break Switch

The air break switches can be broadly classified into two categories, namely single-pole air-break switch and the gang operated air-break switch.

Single-Pole Air Break Switch

A single-pole air break switch provides an opening for only one conductor. The working of a single-pole air break switch is similar to that of a normal air break switch.

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Gang Operated Air Break Switch

A gang operated air break switch is used when the opening of more than one conductor at a time is required. Here, all the switches tend to open and close together.

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Post time: Mar-26-2022