A vacuum circuit breaker is a type of circuit breaker that uses a vacuum as the arc extinguishing medium. When the contacts of the breaker open, an arc is generated between them due to the current flow. The vacuum inside the breaker extinguishes this arc by quickly cooling and de-ionizing the arc plasma. This type of circuit breaker is often used in medium to high voltage applications where high reliability and fast operation are required. Vacuum circuit breakers are known for their high breaking capacity, low maintenance requirements, and long service life.