Transformer fire at Macapá substation causes 22-day blackout in much of Amapá, Brazil

What happened

On 3 November 2020 a fire hit the most important substation in the state of Amapá, Brazil, in the North Zone of Macapá. The fire was in the TR1 transformer and also damaged the neighbouring TR2 transformer, which could not then serve part of the load. The third transformer, TR3, had been under maintenance since December 2019. Thirteen of the state's 16 cities lost electricity. The blackout affected running water, internet and telephone services, and traders could not keep food refrigerated.

The Ministry of Mines and Energy said supply was restored on 24 November, after 22 days. The federal government issued provisional measures exempting consumers in Amapá from electricity bills for 30 days and opening 80 million reais of extraordinary credit. An investigation was opened, and the cause of the fire was not known at the time of the report.

Contributing factors

The cause of the TR1 fire was not known. An energy specialist quoted by the source suggested deterioration of insulation, contamination of insulating oil and overload as possible factors, not as findings. The state is supplied by a radial transmission line with no alternative route. The TR3 transformer had been under maintenance since December 2019, and the fire also damaged TR2, leaving no spare transformer capacity.

Lessons learned

1. A substation that supplies a whole region needs real redundancy, and a transformer out for maintenance should be returned to service quickly or covered by a spare.
2. Transformers should be separated by fire walls or distance so that a fire in one does not damage its neighbour.
3. Oil condition, insulation health and loading should be monitored on critical transformers.
4. Regions fed by a single radial line need contingency plans for mobile transformers or generation.
5. Long maintenance outages on critical substations should be checked so that cover is not lost.

Source

canalsolar.com.br