South Korean government investigation blames poor protection and installation for 23 ESS fires

A public-private joint investigation committee in South Korea released the findings of a five-month probe into 23 energy storage system (ESS) fires reported nationwide from August 2017 onwards, announced by the Ministry of Trade, Industry and Energy on 11 June 2019. The illustrative case pictured by the source was a fire at the Korea Electric Power Corporation (KEPCO) Test Center in Sangha-myeon, Gochang-gun, North Jeolla Province. The committee of 19 experts carried out on-site investigations at 23 accident sites, analysed data and ran 76 verification tests. It found that 14 of the fires occurred while systems were on standby after being fully charged, 6 during charging or discharging, and 3 during installation and construction. Four causes were identified: inadequate battery protection systems against electrical shocks, poor management of the operating environment, careless installation, and the absence of integrated control and protection for the ESS as a single system. Testing showed that a simulated external electrical shock could cause the DC contactor inside a battery rack protection device to explode and damage the busbar, with a secondary short circuit to the device housing igniting simultaneous fires. Tests simulating moisture, dust and salt water also produced a fire in batteries from one unnamed manufacturer through loss of insulation performance within the module. Manufacturing defects such as plate folding, cutting defects and poor active material coating were found in some cells, but did not cause fires in simulation, though the committee said such cells could become a risk factor over long service under harsh conditions. The government had already recommended in January 2019 that private ESS sites suspend operations, and about 35 per cent of 1,490 ESS sites are reported to have stopped operating. This entry records an aggregate official investigation, not a single site event.

Inadequate battery protection devices against electrical shocks; poor management of the operating environment including moisture, dust and salt exposure; careless or faulty installation and wiring; absence of an integrated control and protection system covering the ESS as one unit; insulation degradation within battery modules from one unnamed manufacturer in test conditions.

1. Battery storage systems should be fitted with robust electrical protection devices and emergency stop systems, designed so that a fault in a rack protection device cannot propagate through a secondary short circuit.
2. Operating environment conditions such as temperature, humidity, dust and salt exposure should be controlled and monitored throughout the operating life, not only at commissioning.
3. Installation quality, including wiring and battery handling and storage, should be inspected and signed off, since installation defects contributed to several of the fires reviewed.
4. An ESS should be designed, protected and assessed as a single integrated system rather than as separately certified components.
5. Cells with manufacturing defects may pass initial testing yet become a risk under long service in harsh conditions, so incoming quality control and long-term condition monitoring both matter.

News report via Google News