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Air Blast Circuit Breaker - Coggle Diagram
Air Blast Circuit Breaker
Principle
An Air Circuit Breaker is an automatically operated electrical switch that uses air to protect an electrical circuit from damage caused by excess current from an overload or short circuit. Its primary function is to interrupt current flow after a fault is detected.
Advantage
Cheapness and free availability of the interrupting medium, chemically stable and inertness of air
Air blast circuit breakers have advantage of high speed operation
In air blast circuit breaker fire hazard is eliminated unlike in oil circuit breakers
Short and consistent arcing time and therefore, less burning of contacts
Air blast circuit breakers require less maintenance
They are suitability for frequent operation
Facility for high speed re-closure
Disadvantage
An air compressor plant has to be installed and maintained
The air blast circuit breaker produces a high level of noise when air is discharged to the open atmosphere
In air blast circuit breaker current chopping problem exists
There is a problem of re-striking voltage
Type
The fixed and moving contacts are kept in a closed position by spring pressure under normal operating conditions. The air reservoir tank is connected to the arc chamber through an air valve, which is opened by a triple impulse.
the flow of air is longitudinal along the arc. Air blast circuit breaker may be a single blast or double blast.
When the fault occurs, the tripling impulse causes opening of the air valve connecting the reservoir to the arcing chamber. The air entering the arc chamber exerts pressure on the moving contacts which moves when the air pressure exceeds the spring force.
A moving contact arm is operated in close spaces to draw an arc which is forced by a transverse blast of air into the splitter plates, thereby lightening it to the point when it cannot restrike after zero current.
