![]() When the main contacts opened the arcing contacts are still in touch with each other.Īs the current gets a parallel low resistive path through the arcing contact. When the circuit breaker is being opened, the main contacts open first. The second pair is the arcing contact (2) and is made of carbon. The main pair of contacts (1) carries the current at normal load and these contacts are made of copper metal. The below-shown figure illustrates the principle of air breaker circuit operation.Īir Circuit breakers generally have two pairs of contacts. They are always used for the low-voltage interruption and now tends to replace high-voltage oil breakers. Their method of arc quenching control is entirely different from that of oil circuit-breakers. The circuit breaker is outdated for average voltage.Īir circuit breakers operate with their contacts in free air. Whenever arc contacts are divided then arcing gets started. While opening the major contact, the arc contact stays connected.Once the circuit breaker is opened, the first major contact unlocks. Another pair of contact can be made with carbon. It includes two sets of contact where the major pair uses the current as well as the contact made with copper. The range of operating voltage is upto 1KV. ![]() As soon arc path length is enhanced then the path of resistance will also increase the arc voltage which is used across the arc path thus arc voltage can be increased. Once the arc path is increased then Arc voltage can also be increased.The arc voltage can be increased by splitting the arc into several series Once the temperature of arc plasma and particle motion is reduced, then additional voltage gradient will be necessary to keep the arc.The arc voltage can be enhanced through cooling arc plasma.The voltage supply can be increased in three different ways by a circuit breaker. This voltage can be defined as the least voltage which is necessary to maintain the arc. While interrupting an arc, it makes an arc voltage in place of the voltage supply. The air circuit breaker also works the same but in a different way.We know that the basic function of CB is to stop the restoration of arcing wherever the gap between contacts will resist the recovery voltage of the system. The air circuit breaker working principle is different as compared with other kinds of CBs.The internal parts of ACB mainly include supporting structure with steel sheet, the current transformer used to protect the trip unit, pole group insulating box, horizontal terminals, arcing chamber, trip unit for protection, terminal box, closing springs, CB opening & closing control, plates to move arcing and main contacts, plates for fixed main & arcing contacts. The external parts of ACB mainly include the ON & OFF button, an indicator for the position of the main contact, an indicator for the mechanism of energy storage, LED indicators, RST button, controller, rated nameplate, handle for energy storage, displays, shake, fault trip rest button, rocker repository, etc.
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