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Why does an air circuit breaker have to create an arc voltage ?

Air circuit breakers create an arc voltage as a result of the interruption process during circuit breaking. When the circuit breaker opens, it creates a gap between its contacts. The current flowing through the circuit generates an electric arc across this gap.

The arc voltage is essential because it plays a crucial role in the interruption process. The voltage across the arc sustains the arc itself. As the contacts separate, the medium between them, which is air in the case of an air circuit breaker, becomes ionized due to the high current. This ionization forms a conductive path for the arc.

The arc voltage serves two primary purposes. First, it allows the current to continue flowing across the gap, ensuring a sustained arc. Second, the voltage drop across the arc contributes to reducing the current to a level where it can be safely interrupted without causing excessive damage to the contacts.

The circuit breaker is designed to control and extinguish this arc effectively. Various methods, such as using arc chutes and magnetic fields, are employed to enhance the interruption process. The arc voltage is a critical component in the overall operation of the air circuit breaker, facilitating the safe and efficient interruption of the current flow when the circuit needs to be disconnected or isolated.

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