Ministry of Industry Announces Final Results of Cause Investigation for Okdong Substation Failure
The final investigation results revealed that the failure of the 'Okdong Substation,' which caused a blackout in Ulsan on December 6 last year, was due to non-compliance with work procedures and other factors.
The Ministry of Trade, Industry and Energy announced on the 18th that the investigation team into the cause of the Okdong Substation failure had released these final findings.
Following the blackout affecting approximately 155,000 households in the Ulsan area at the end of last year, the ministry activated the investigation team to fundamentally review improvements needed due to the increasingly complex power grid conditions and aging equipment.
The ministry formed an investigation team on December 8, 2023, to identify the cause of internal damage to the gas-insulated switchgear (GIS) at the Ulsan Okdong Substation and conducted the investigation over 133 days.
The team concluded that the cause of the Okdong Substation failure was due to the construction company and supervisor’s non-compliance with work procedures and inadequate work management. Specifically, after replacing the GIS, the gas leak repair work should have been performed with valves outside the work section closed; however, some valves were left open unnoticed, and the procedure to release the insulating gas (SF6) was carried out, resulting in the destruction of the GIS.
To analyze this, the investigation team classified possible causes of failure into three categories: material defects, construction defects, and repair work. They conducted investigations including examination of failure debris and pressure data, as well as demonstration experiments. Based on the results, they recommended strengthening construction and supervision systems to prevent work errors, enhancing work procedure management, and ensuring compliance with safety regulations.
Korea Electric Power Corporation (KEPCO) announced at the on-site reinspection meeting at Okdong Substation that it will completely improve the management system of transmission and distribution facilities to minimize public damage caused by the blackout. To this end, KEPCO plans to actively invest approximately 4 trillion won in transmission, substation, and distribution sectors by 2034. Additionally, KEPCO will compensate for reported damages after damage assessments, with payments scheduled for May.
Lee Ho-hyun, Director of the Energy Policy Office at the Ministry of Trade, Industry and Energy, stated, "Based on the rigorously investigated cause of the Okdong Substation failure, please maintain the world's highest level of stable power supply by fully improving the power facility management system through the use of artificial intelligence (AI) and enhancement of manuals." He also urged, "Please thoroughly prepare to ensure that KEPCO’s blackout prevention investment projects proceed without any setbacks."
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