Indonesia’s National Police (Bareskrim Polri) have identified several possible causes behind the failure of a transmission cable that triggered a widespread power blackout across Sumatra on Friday (May 23).
The outage disrupted electricity supply across multiple provinces on the island, prompting a joint investigation involving the National Police’s Criminal Investigation Agency, the Forensic Laboratory Center (Puslabfor), and state electricity company PLN.
Deputy Head of Bareskrim, Inspector General Nunung Syaifuddin, said preliminary findings suggest that extreme weather conditions may have played a key role in the incident.
“The cause of the transmission cable failure is still under investigation, with several possibilities being explored, including mechanical factors due to friction and the impact of strong winds,” Nunung said during a press conference on Monday (May 25).
He added that other potential causes being examined include overheating at cable joints due to loose connections, which may have created gaps, as well as stress from cable movement caused by severe weather conditions.
According to him, these factors may have led to instability in frequency and voltage across the power grid, triggering a cascading failure in power plants through automatic protection systems.
This chain reaction ultimately resulted in a large-scale blackout affecting Aceh, North Sumatra, West Sumatra, Riau, Jambi, and parts of South Sumatra.
Despite the widespread disruption, initial inspections at the suspected origin point showed that the transmission tower itself remained structurally intact, with no significant damage detected.
“At the initial point of disturbance, the physical condition of the transmission tower is confirmed to be in good condition,” Nunung said.
He also noted that witness accounts from residents near the site supported the hypothesis of an electrical disturbance occurring just before the blackout.
“Witnesses reported hearing a small explosion shortly before a sudden power outage occurred in the area surrounding the transmission tower,” he added.
However, authorities stressed that there is currently no evidence suggesting sabotage or intentional interference.
“As of now, we can confirm that there are no indications of sabotage or deliberate actions behind the blackout incident,” Nunung stated.
He further urged the public not to spread misinformation regarding the cause of the outage.
Examination of recovered cable fragments also indicated that the damage pattern was inconsistent with intentional cutting.
“The damage appears more frayed in nature. If it were sabotage, the cuts would typically be cleaner,” he explained.
Police and PLN continue to investigate the incident to determine the exact cause of the transmission failure and to assess the resilience of the regional power grid against extreme weather conditions and technical stress.
