Recloser

[3] Reclosers are designed to handle a brief open-close duty cycle, where electrical engineers can optionally configure the number and timing of attempted close operations prior to transitioning to a lockout stage.

Automatically closing the breaker after it has tripped and stayed open for a brief amount of time, usually after 1 to 5 seconds, is a standard procedure.

Interrogation and remote operation capabilities allow utilities to aggregate data about their network performance, and develop automation schemes for power restoration.

Controls for the reclosers range from the original electromechanical systems to digital electronics with metering and SCADA functions.

The advent of semiconductor based electronic protective relays in the 1980s resulted in increased recloser sophistication, allowing for differing responses to the various cases of abnormal operation or fault on an electric power distribution network.

These protection solutions present a major problem when restoring power immediately following transient events, because repair crews need to manually reset the circuit breakers or replace fuses cutouts.

Alternatively, reclosers are programmed to automate the reset process remotely after a short circuit and allow a more granular approach to service restoration, resulting in increased availability of supply.

Reclosers with sensitive earth fault protection capable of detecting 500 mA and below are used as a fire mitigation technique, as they provide an 80% risk reduction in fire starts,[13] however they are never to be used as reclosers in this application, only as single shot distributed circuit breakers which allow for sensitivity to verify the existence of these faults.

[14] Traditional reclosers were designed simply to automate the action of a line crew visiting a remote distribution site to close a tripped circuit breaker and attempt to restore power.

With the advanced protection functionality of modern reclosers, these devices are used in a multitude of additional applications Residential customers in areas fed by affected overhead power lines can occasionally see the effects of an autorecloser in action.

Reclosers may cooperate with down-stream protective devices called sectionalizers, usually a disconnector or cutouts equipped with a tripping mechanism triggered by a counter or a timer.

Regardless of the choice of distribution protection switchgear, the fire risk is always higher with overhead conductors than with underground transmission.

Research into the Australian 2009 Black Saturday Bushfires indicated that reclosers operating as single shot circuit breakers with Sensitive Ground Fault protection configured at 500mA would reduce fire start risk by 80%.

[13] Victorian utilities responded to the Royal Commission by converting some of their overhead network in high risk areas to underground cable, replacing exposed overhead conductors with insulated cables, and replacing old reclosers with modern ACRs with remote communications to ensure that settings can be adjusted on high bushfire risk days.