Arc flash at Astoria transmission substation in Queens disrupts supply and airport

On the night of 27 December 2018, an electrical fault occurred on 138,000 volt equipment at the Astoria transmission substation in Astoria, Queens, New York City, operated and owned by Consolidated Edison. The fault developed into a sustained arc flash, accompanied by a brief electrical fire involving transformers and a transmission dip across the surrounding area. Smoke was seen coming from transformer equipment and an intense blue light from the arc was visible across a wide area of the metropolitan region, with many members of the public photographing and filming it. Supply to a nearby major airport was affected; power was largely restored by about 23:00 the same evening and the airport resumed normal operations, with travellers advised to confirm flight information with their carriers. Consolidated Edison reported that the affected equipment was confined to a single section within the substation and that all major transmission lines associated with the event had been restored. An investigation into the failure was opened.

Consolidated Edison stated publicly that an electrical fault on the 138 kV equipment at the Astoria substation caused a sustained arc flash, and that the affected equipment was isolated to a single section within the substation. Specific causation was the subject of a formal investigation and no root cause had been published at the time of the source report. No further contributing factors were stated by the sources.

1. Identify which nearby critical facilities, such as airports, hospitals and transport hubs, depend on a given substation, and agree contingency and notification arrangements with those facility operators in advance.
2. Review physical and electrical segregation between substation sections so that a fault in one section is less likely to propagate, as reported in this event.
3. Prepare public communication in advance for faults at urban high voltage substations, since such events are visible over long distances and generate rapid public and media attention before technical facts are confirmed.
4. After any arc fault, review protection records to confirm whether main protection operated within its design time, whether backup protection was called upon, and whether revised settings would reduce arc energy.
5. Include infrared thermography and partial discharge testing in routine substation inspection programmes to identify pre-failure indicators in switchgear and transformers.
6. Plan for two timescales after a major substation fault: network reconfiguration and supply restoration within hours, and equipment repair, replacement and investigation that may run for months.

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