What is the primary function of vacuum interrupters in a circuit breaker?

The primary function of vacuum interrupters in a circuit breaker is to extinguish an arc during the interruption process in a vacuum environment. When a fault occurs in an electrical system, a surge of current can create an arc across the contacts within the circuit breaker. This arc needs to be quickly and effectively extinguished to protect the system and ensure it functions safely.

Vacuum interrupters achieve this by using the principle that, in a vacuum, there are very few gas molecules that can support or sustain an arc. When the contacts separate within the interrupter, the arc that forms quickly dissipates due to the lack of ambient air or gas to sustain it, allowing the circuit to be safely interrupted without damaging the components. This makes vacuum interrupters highly efficient and reliable for protecting electrical systems from fault conditions, which is critical for the safe operation of switchgear.