recloser

If the fault is still present, the recloser opens again.

Since the network is rural, most of these faults will be cleared by the recloser.

The control system for a recloser allows a selected number of attempts to restore service after adjustable time delays.

Meanwhile, downstream sectionalizers automatically count current interruptions by the recloser.

A sectionalizer is generally not rated to interrupt fault current and is therefore cheaper than a recloser.

Since many short-circuits on overhead lines clear themselves, a recloser improves service continuity by automatically restoring power to the line after a momentary fault.

Each sectionalizer detects and counts fault current interruptions by the recloser (or circuit breaker).

Smaller distribution stations may use recloser circuit breakers or fuses for protection of distribution circuits.

This means that a single event on the grid will cut off only the section handled by the single recloser, long before the feeder station would notice a problem.

After a pre-determined number of interruptions, the sectionalizer will open, thereby isolating the faulty section of the circuit, allowing the recloser to restore supply to the other non-fault sections.

In electric power distribution, a recloser, or autorecloser, is a circuit breaker equipped with a mechanism that can automatically close the breaker after it has been opened due to a fault.

This method can be guaranteed to work, but requires the grid to be equipped with automated recloser systems, and external communications systems that guarantee the signal will make it through to the reclosers.

Common types of IEDs include protective relaying devices, On Load Tap Changer controllers, circuit breaker controllers, capacitor bank switches, recloser controllers, voltage regulators, etc.

When a sectionalizer detects a preset number of interruptions of fault current (typically 3 or 4) the sectionalizer opens (while unenergized) and remains open, and the recloser restores supply to the other non-fault sections.

As the utility can be reasonably assured that they will always have a method for discovering a fault, whether that be automated or simply looking at the recloser, it is possible for the utility to use this information and transmit it down the line.

This can be used to force the tripping of properly-equipped DG systems by deliberately opening a series of recloser in the grid to force the DG system to be isolated in a way that forces it out of the NDZ.

For example a recloser may have 2 or 3 "fast" reclose operations with a few seconds delay, then a longer delay and one reclose; if the last attempt is not successful, the recloser will lock out and require human intervention to reset.