PLN says bad weather caused Sumatra blackout

PT PLN (Persero) said that a blackout or widespread electricity outage in Sumatra on Friday, 22 May 2026, from 18:44 WIB, was caused by bad weather which then affected part of Sumatra’s power system.

‘An outage on the transmission line extended to part of Sumatra’s transmission system, causing a frequency drop due to heavy load on the generators and triggering a domino effect of disturbances in several regions,’ said PLN President Director Darmawan Prasodjo in a press release on Saturday, 23 May 2026, as quoted by Antara.

Darmawan said that from the outset of the disturbance, PLN immediately moved to inspect and restore the electricity system. He explained that within around two hours the affected transmission network was restored.

After restoring the transmission network, he said, PLN’s main focus was to operate the generators that were affected to re-synchronise them with the transmission system that had been prepared.

He explained that the generator start-up process was conducted systematically and gradually, with safety of the system prioritised. Hydro and gas-fired plants can immediately help supply the system as a rapid response to speed up initial recovery.

‘Meanwhile thermal plants such as PLTU will require a longer time, between 15 and 20 hours from start-up, synchronisation and full operation,’ he said.

Recovery was carried out simultaneously from the transmission network, main substations, to the power plants in Sumatra’s electricity system. To support the process, PLN deployed hundreds of personnel working 24 hours across affected areas from Jambi, West Sumatra, Riau, North Sumatra and Aceh.