Substation transformer fire causes island-wide blackout in Puerto Rico

What happened

A fire, described by the island's governor as an explosion, broke out in a transformer at the Monacillos substation in Río Piedras, San Juan, Puerto Rico. The incident caused major blackouts across the island, with utility operator LUMA Energy reporting that about 400,000 customers remained without power late on the day of the incident, after a peak of 800,000 customers affected. Police, fire department and medical emergency personnel responded to the scene.

No injuries were reported. Both state and federal law enforcement authorities, including the FBI, opened investigations into the cause. The incident occurred just over a week after LUMA Energy took over operation of Puerto Rico's power grid from the previous public utility, PREPA, on 1 June 2021. LUMA also reported that its website had been hit by a separate distributed denial of service cyberattack earlier the same day, though no connection to the substation fire was confirmed.

Contributing factors

The specific technical cause of the transformer fire had not been determined at the time of reporting and was under investigation by state and federal authorities. The incident occurred shortly after a change of grid operator, though no causal link to the transition was reported.

Lessons learned

1. A single transformer failure at a key substation can cause island-wide blackouts when grid redundancy is limited.
2. Operator transition requires early review of legacy equipment condition to limit risk of sudden failures.

More lessons on maintenance, inspection and ageing assets, from every incident on the register.

Not yet known

• Technical cause of the transformer fire
• Transformer model and age
• Duration of the outage
• Cost of the damage

This entry is updated when these are reported. Get an alert for the next one like it.

Source

CNN (cnn.com)