Police and PLN Confirm Broken Cable Caused Sumatra Power Outage

Jakarta, CNBC Indonesia - The Indonesian National Police’s Criminal Investigation Agency (Bareskrim) and PT PLN (Persero) have displayed a broken cable as the cause of the Sumatra power outage, confirming the electrical system disturbance was not due to sabotage or intentional acts. Bareskrim stated that preliminary investigation results indicate the disruption was likely caused by technical issues and extreme weather. Deputy Chief of Bareskrim, Inspector General of Police Nunung Syaifudin, explained that a joint team from the Special Crime Directorate, General Crime Directorate, Bareskrim Forensic Lab, Jambi Provincial Police Criminal Investigation Unit, and PT PLN conducted field investigations at a transmission tower site in Tempino Village, Mestong District, Muaro Jambi Regency, Jambi Province. Initial identifications revealed that on Friday, 22 May 2026, at approximately 18:44 WIB, a disruption occurred in the 275 kV transmission line between Muara Bungo and Sungai Rumbai in Jambi, likely triggered by severe weather. The disturbance caused the transmission system to disconnect from Sumatra’s power grid, leading to frequency and voltage instability. This resulted in a cascading failure of power plants, causing a widespread blackout across several Sumatran regions, including Aceh, North Sumatra, West Sumatra, Riau, Jambi, and parts of South Sumatra. ‘Initial identifications confirmed that the disruption in the 275 kV transmission line between Muara Bungo and Sungai Rumbai was likely caused by severe weather, leading to the transmission system disconnecting from Sumatra’s power grid,’ said Inspector General Nunung Syaifudin during a press conference on Monday, 25 May 2026. The joint field team also found a broken transmission cable around the transmission tower. However, the tower structure remained intact with no significant damage. According to Nunung, the preliminary cause of the cable break 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. ‘To date, we can confirm there are no indications 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 exhibited a frayed pattern rather than a clean cut, which would suggest sabotage. The damaged section has been secured and is undergoing forensic laboratory analysis by Bareskrim’s Forensic Lab to determine the precise cause scientifically. At the same time, PT PLN’s Transmission and System Planning Director, Edwin Nugraha Putra, 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 disruption, the transmission lines tripped due to heavy rain and strong winds. This caused a power flow reversal, triggering a significant power swing — a high oscillation in voltage and frequency. As a result, Sumatra’s power system split into two sections: the southern region with excess generation capacity and the northern region with insufficient power. The northern area experienced cascading generator trips, or a domino effect, leading to blackouts in affected areas. PLN then carried out a staged recovery using a black start mechanism with diesel and gas generators, followed by restarting gas-fired and coal-fired power plants until the entire system returned to normal. ‘All of Sumatra’s power systems have been fully restored to 100 percent and are now operating safely and stably,’ Edwin said. PLN confirmed that on Monday, 25 May 2026, several major power plants were reintegrated into the system, ensuring stable and secure electricity supply across Sumatra.