High-voltage flash and fire at Patuli substation in Kolkata

On 27 March 2020, a high-voltage flash and fire occurred at the Patuli substation, an 11 kV distribution substation operated by Calcutta Electric Supply in south Kolkata. The substation shut down at around 6 p.m. with an arc flash and a loud bang. Thick black smoke prompted residents to alert the fire brigade. Seven fire tenders attended and the fire was doused by 7:10 p.m. Several thousand households in the affected area lost supply, with power switched off in some areas as a safety measure while supply was rerouted from other feeders. Calcutta Electric Supply said power to the affected zone would be restored before midnight. Parts of the substation were left waterlogged from firefighting, and the utility said the equipment would need to dry before the cause could be investigated and rectified. Injuries are not reported in the available source. The event was described as the first major emergency in Kolkata after a lockdown was imposed on 23 March 2020.

A Calcutta Electric Supply official said a fault had occurred in the substation switch, leading to a high-voltage flash and the supply breakdown. The full cause was not established at the time of reporting because the equipment was waterlogged and had to dry before inspection.

1. Distribution substations benefit from robust switch maintenance and inspection regimes to reduce the risk of high-voltage flash faults.
2. Alternative feeder routing capability allows supply to be restored to affected zones quickly after a substation is taken out of service.
3. Water used to fight electrical fires can leave equipment unusable for inspection, so operators should plan for drying, isolation and post-incident examination to limit downtime and preserve evidence.

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