Police and PLN Uncover Initial Findings on Sumatra Blackout Cause

The Indonesian National Police (Polri) and state electricity company PLN have revealed initial findings regarding the blackout that affected much of Sumatra last weekend. Initial investigations suggest that a fault in Jambi’s transmission network was the primary trigger for the disconnection of Sumatra’s interconnected power system, leading to widespread outages reaching Aceh. Deputy Chief of the Criminal Investigation Agency (Wakabareskrim) of the Indonesian National Police, Inspector General Nunung Syaifuddin, stated that a joint investigation began on Sunday, 24 May 2026, involving the Special Crimes Directorate, General Crimes Directorate, Forensic Science Centre (Puslabfor), Jambi Provincial Police’s Special Crimes Unit, and PLN teams. Field inspections focused on transmission towers 175 and 176 of the 275-kilovolt (kV) SUTET network in Tempino Village, Mestong Subdistrict, Muaro Jambi Regency, Jambi Province. ‘Initial identification revealed that on Friday, 22 May 2026, at approximately 6:44 pm WIB, a fault occurred in the 275 kV SUTET transmission line between Muara Bungo and Sungai Rumbai in Jambi,’ Nunung said during a press conference at the Polri Criminal Investigation Agency building in Jakarta on Monday, 25 May 2026. This led to instability in frequency and voltage, triggering a cascading power plant shutdown. ‘As a result, a widespread blackout affected several regions across Sumatra, including Aceh, North Sumatra, West Sumatra, Riau, Jambi, and parts of South Sumatra,’ he added. What were the key findings by Polri and PLN regarding last week’s Sumatra blackout? During field inspections, the joint team found a broken transmission cable around the transmission tower in Tempino Village, Jambi. However, the physical structure of the towers was generally intact with no significant damage found. ‘Based on initial field reports, the transmission cable breakage is suspected to have occurred suddenly due to weather factors and requires further technical and scientific investigation,’ Nunung said. Witnesses interviewed included local RT (neighbourhood head) officials and residents. Polri has secured the broken transmission cable segment for further analysis by the agency’s Forensic Science Centre.