Air Break Switch – Types and Uses

Air Break Switch Disconnectors are a vital part of any overhead line network, providing crucial points of isolation.

Most overhead line networks are designed so that when a fault occurs or maintenance work needs to be carried out it is relatively simple, by means of a systematic series of switching operations, to isolate a certain section of the overhead line.

When this switching process is carried out it is absolutely imperative that the Air Break Switch Disconnector is reliable and effective.

A recloser is a lot like a circuit breaker both in function and also the choice of the dielectric. Reclosers typically have less short circuit interrupting capacity than breakers, but they are designed to automatically reclose to restore the interrupted circuit.

The reason for that is that most (typically, more than 80% of the faults on overhead distribution circuits are self-clearing (tree branches, small animals, etc) and can be restored if the circuit is allowed to remain de-energized for 10-15 seconds so that the ionized air in the vicinity of the fault can dissipate. Reclosers are much less expensive than breakers.

A sectionalizer is a device that is applied out on a distribution circuit that is intended to determine that a fault is located downstream of the recloser.

The principle of operation is that once the sectionalizer makes the determination that the problem is downstream, it can open, and then an upstream reclosing device (either a recloser or a circuit breaker) can automatically reclose to restore service to those loads that are upstream of the sectionalizer.

A sectionalizer doesn’t have any current interrupting capability but instead relies on the upstream device to interrupt fault current.