ESDM cites lightning strike as cause of Sumatra blackout

Jakarta, CNBC Indonesia - The Ministry of Energy and Mineral Resources (ESDM) has revealed the cause of the power blackout that occurred in Sumatra on Friday, 22 May 2026. The government confirmed that the primary reason for the outage was a natural event — a lightning strike on the interconnection network in Merangin, Jambi.

Deputy Energy Minister Yuliot Tanjung stated that a team had been deployed to verify the technical aspects. “Regarding the electricity incident in Sumatra, there was an issue with the transmission line struck by lightning in Merangin. This lightning strike affected system stability,” Yuliot said during a meeting at the DPR Building in Jakarta on Monday, 25 May 2026.

Yuliot explained that the lightning strike disrupted power delivery to North Sumatra, which heavily relies on supply from the south. He said the interruption at the Merangin transmission point triggered all automatic safety systems, causing a complete power halt.

“The incident caused the entire system to go into blackout,” Yuliot added.

Yuliot also addressed circulating claims of possible intentional involvement in the power outage. The ESDM stated it found no signs of sabotage and confirmed the incident was due to extreme weather affecting the country’s power infrastructure.

“No, there was no intentional involvement. It was purely due to natural conditions,” he stressed.

As mitigation, the Government instructed PT PLN (Persero) to immediately conduct audits and technical repairs on vulnerable lines. The focus is on strengthening lightning protection systems and balancing power plant locations to avoid concentration in one area.

“System improvements include installing earthing systems in high-risk areas, and ensuring balanced power supply across regions,” he concluded.

Bareskrim Investigation Results

The Indonesian National Police’s Bareskrim, alongside PT PLN (Persero), released preliminary findings regarding the power system disturbance or blackout that affected several Sumatran regions on Friday, 22 May 2026. The preliminary results indicate the disturbance was likely caused by technical issues and extreme weather, with no evidence of sabotage or intentional acts.

Deputy Chief of Bareskrim, Inspector General Nunung Syaifudin, explained that a joint team from the Special Crimes Directorate, General Crimes Directorate, Bareskrim Forensic Laboratory, Jambi Provincial Police Special Crimes Unit, and PT PLN conducted on-site investigations at the transmission tower site in Tempino Village, Mestong Subdistrict, Muaro Jambi Regency, Jambi Province.

Initial identification showed that on Friday, 22 May 2026, around 6:44 PM WIB, a disturbance occurred in the 275 kV transmission line between Muara Bungo and Sungai Rumbai in Jambi, likely triggered by severe weather. This caused the transmission system to disconnect from Sumatra’s power grid, leading to frequency and voltage instability.

As a result, several power plants tripped in a chain reaction, causing a widespread blackout across Aceh, North Sumatra, West Sumatra, Riau, Jambi, and parts of South Sumatra.

“Initial identification revealed that the disturbance in the 275 kV Muara Bungo-Sungai Rumbai transmission line was likely caused by severe weather, leading to the transmission system disconnecting from Sumatra’s power grid,” said Inspector General Nunung during a press conference on Monday, 25 May 2026.

The joint team also found a broken transmission cable near the transmission tower. However, the tower structure was generally intact with no significant damage.

According to Nunung, the preliminary cause of the broken cable is still under investigation, with possible factors including mechanical wear from friction and wind, heat from loose connections causing electrical arcing, or strain and movement due to extreme weather.

“We can confirm there is no indication of sabotage or intentional acts in the blackout incident. The preliminary suspicion points to technical issues and extreme weather,” he stressed.

He also explained that initial examinations showed the cable damage was frayed, not neatly cut, indicating no sabotage. The broken cable section has been secured and is undergoing forensic laboratory testing by Bareskrim’s forensics unit to determine the exact cause scientifically.

PLN Speaks Out

Edwin Nugraha Putra, Director of Transmission and System Planning at PT PLN (Persero), explained that Sumatra’s power system has two main transmission corridors carrying power from south to north: the 500 kV eastern corridor and the 275 kV western corridor.

During the disturbance, the transmission lines tripped due to severe weather, including heavy rain and strong winds. This caused power flow reversal and triggered a high-amplitude power swing, or voltage and frequency oscillation.

As a result, Sumatra’s power system split into two sections: the south with excess generation and the north with insufficient supply. The northern region’s situation caused a cascading trip of generators, leading to outages across affected areas.

PLN then initiated a gradual recovery process using black start mechanisms with diesel and gas generators, followed by the operation of PLTGU and PLTU units until