PUTRAJAYA: A circulating current has been identified as the main cause of the blackout at the KLIA Terminal 2 on Aug 28.
The Transport Ministry stated that the finding was derived from a technical investigation carried out by Malaysia Airports Holdings Bhd (MAHB), which was acknowledged in a report by the Cabinet on Wednesday.
“MAHB’s technical investigation found that the main cause of the incident was the presence of a circulating current along the cable route between the 33kV substation supplying power to Terminal 2 and the 11kV substations at the terminal.
“This condition caused localised heating at the cable termination, which led to a flashover incident,” it said in a statement yesterday.
The ministry said high soil resistivity was also identified as an indirect contributing factor, as it prevented effective dissipation of current into the ground, thereby increasing thermal stress on sheath wires.
Following the incident, MAHB’s technical team carried out immediate measures, including repairing all cable terminations, installing sheath voltage limiters at cross-bonding locations to reduce the effect of circulating current, and reassessing and reconfiguring the earthing installation.
“Another step was enhancing the maintenance regime by incorporating partial discharge tests and thermographic inspections into the planned preventive maintenance programme for power cables,” the statement said.
MAHB has also identified long-term improvement measures, including studying the feasibility of installing an Automatic Transfer Switch system to speed up backup power supply and optimising generator use to protect more critical services.
Other measures include reducing the preventive maintenance interval for genset load testing at Gateway@klia2 from once every three months to once every two months, which aims to improve reliability and facilitate early detection of flashover incidents.
“Also, a comprehensive study of soil resistivity along the cable routes will be conducted, including seasonal analysis and the effectiveness of earthing and cross-bonding systems, to better control circulating current risks and improve earthing efficiency in the future,” the ministry said.
According to the ministry, MAHB has confirmed that no critical airport operations were affected by the incident.
“The Transport Ministry will continue to monitor the implementation of MAHB’s follow-up measures to ensure the highest level of safety, efficiency and reliability of systems at KLIA,” it said.
