ESS Fire Secondary Investigation Team: "4 out of 5 Cases Caused by Battery"

Fire ignited from batteries in 'Yesan, Pyeongchang, Gunwi, Gimhae'... Battery protection device in Pyeongchang did not operate properly

Hadong fire caused by contact with external foreign substances

Investigation team: "Operating method with charge rate above 95% is problematic... Lowering charge rate contributes to fire prevention"

Battery module at the ignition point (left) and system operation records of the ESS in Yesan, Chungnam, where a fire occurred on August 30 last year.

[Sejong=Asia Economy Reporter Joo Sang-don] An investigation revealed that 4 out of 5 energy storage system (ESS) fires that occurred since August last year were caused by battery abnormalities.

The ESS secondary fire accident investigation team announced the cause investigation results containing this information on the 6th.

The investigation team was formed on October 17 last year, consisting of 20 members including academics, research institutes, National Assembly, and Fire Agency officials. The investigation targets were five cases in total, including the ESS fire in Yesan, Chungnam on August 30 and the ESS fire in Gimhae, Gyeongnam on October 27 of the same year. The team analyzed previous investigation committee results and operational records of the accident sites, conducted on-site investigations, battery disassembly and analysis, inspections of similar ESS sites, 3D X-ray CT scans, and verification tests.

The investigation team estimated that the causes of ESS fires installed in Yesan, Chungnam (battery manufacturer: LG Chem), Pyeongchang, Gangwon (Samsung SDI), Gunwi, Gyeongbuk (LG Chem), and Gimhae, Gyeongnam (Samsung SDI) were due to battery abnormalities. The remaining site in Hadong, Gyeongnam (LG Chem) was concluded to have caught fire due to contact with external foreign substances on the exposed pressurized charging part.

According to the investigation results, the ESS installed in Migok-ri, Gwangsi-myeon, Yesan-gun, Chungnam, where the fire occurred at 7:18 PM last August, was analyzed through system operation records (EMS) to have ignited at the battery. The battery collected from the ignition point during the on-site investigation showed melting traces typical of ignition.

The possibility of fire caused by external environmental factors was considered low. Although electrical resistance, which appears when voltage is applied to an insulator that prevents electricity or heat conduction, continuously decreased, it remained above the standard value. Also, there was no damage or burning phenomenon in the power conversion system (PCS), and investigation results of common mode voltage (CMV) and leakage current at similar sites indicated a low possibility of fire caused by electrical factors.

The ESS fire installed on Cheongoksan-gil, Mitan-myeon, Pyeongchang-gun, Gangwon was also considered to have originated from the battery. Past operation records showed charging and discharging beyond the upper voltage limit during charging and lower voltage limit during discharging, and it was confirmed that the battery protection function did not operate in these cases.

The ignition point of the ESS in Seongok-ri, Ubo-myeon, Gunwi-gun, Gyeongbuk was also the battery. CCTV footage confirmed that smoke first appeared from the battery, and analysis of system and battery operation records (EMS, BMS) indicated the battery as the ignition point. The ESS in Jangbang-ri, Hallim-myeon, Gimhae-si, Gyeongnam also showed low voltage and abnormal high-temperature fault signals through EMS, and CCTV footage confirmed initial smoke from the battery, identifying the battery as the ignition point.

In the case of the ESS in Gwankok-ri, Jingyo-myeon, Hadong-si, Gyeongnam, the fire was presumed to be caused by contact with external foreign substances rather than the battery. It was judged that the fire started due to foreign substances contacting the electrically exposed part between the battery and the circuit breaker.

An investigation team official stated, "No fire occurred when the charge rate was limited and kept low, but fires were confirmed after increasing the charge rate," adding, "Strengthening battery maintenance by operating at a lower charge rate will contribute to fire prevention."

This content was produced with the assistance of AI translation services.