Automatic reclosing

Automatic reclosing means a breaker or recloser closes again on its own a limited number of times after a fault trip, so the faulted section gets power back. When the fault was temporary, service comes back with no further action. When the fault is still there, the device trips again, and after its set number of attempts it locks out until someone resets it by hand. Common sequences use 1, 2 or 3 reclosing attempts. On distribution circuits, the open time between attempts is usually set somewhere from about 0.2 s to 30 s. If reclosing happens too fast, a PV inverter may still be running in an island and may have lost synchronism with the grid. Closing out of synchronism counts as a fault and can trip the breaker or damage equipment. A strict reading of IEEE 1547 means PV must disconnect faster than 2 s when the utility recloses in less than 2 s. Utilities can also lengthen the reclose delay, or add voltage sensing or sync-check relaying so the line recloses only when the PV side is de-energized. An inverter that rides through a fault on a nearby section will see a series of voltage dips, one for each reclose attempt. This is why consecutive-disturbance ride-through matters.

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• sentence 7: support check: partial - Passages support a series of disturbances on each reclosure and the DER ride-through requirement, but do not name 'consecutive-disturbance ride-through' as the reason beyond the figure titles; also one dip per attempt applies for a persistent fault. -->