Arc quenching medium in air circuit breaker
In an air circuit breaker (ACB), the arc quenching medium is a critical component that helps to extinguish the arc that forms when the breaker is operated. The arc quenching medium is typically a gas or a mixture of gases that is used to interrupt the electrical arc that occurs when the breaker is opened.
In an ACB, the arc quenching medium is usually a gas such as:
- Air: Air is the most common arc quenching medium used in ACBs. It is a simple and inexpensive option that is effective for interrupting low-voltage arcs.
- SF6 (Sulfur Hexafluoride): SF6 is a widely used arc quenching medium in ACBs. It is a highly effective gas that can interrupt high-voltage arcs and is commonly used in medium-voltage ACBs.
- N2 (Nitrogen): N2 is another gas that is used as an arc quenching medium in ACBs. It is a non-toxic and non-flammable gas that is effective for interrupting low-voltage arcs.
The arc quenching medium is typically contained within the breaker's interrupting chamber, which is designed to withstand the high temperatures and pressures generated by the arc. The interrupting chamber is typically made of a heat-resistant material such as ceramic or metal.
When the breaker is operated, the arc quenching medium is released into the interrupting chamber, where it helps to extinguish the arc. The arc quenching medium works by:
- Cooling the arc: The arc quenching medium helps to cool the arc, reducing its temperature and energy.
- Disrupting the arc: The arc quenching medium disrupts the arc, breaking the electrical path and extinguishing the arc.
- Reducing the arc voltage: The arc quenching medium reduces the arc voltage, making it more difficult for the arc to reignite.
The choice of arc quenching medium depends on the specific application and the requirements of the breaker. In general, SF6 is used in high-voltage ACBs, while air and N2 are used in lower-voltage applications.