Characteristics of the high voltage delivery station (20 kV):
- rubble walls
- concrete slab ceiling
- surface area: 20 m²
A fire broke out in the capacitor banks in the electrical supply station of a medical equipment factory. A fire alarm went off at 9:16 p.m. The emergency plan was initiated and the electricity was switched off (a request was made for firefighter intervention). The employees were evacuated. The rescue services were able to extinguish the fire at around 10:50 p.m. using powder fire extinguishers, then with tanks full of powder.
Impact of the power outage
The disconnection of the site’s electrical power led to the securing of the ethylene oxide destruction equipment of the sterilisation unit. This shutdown resulted in the release of 352 g of ethylene oxide into the atmosphere. The release was quantified using a chromatograph that had been recently installed at the site.
Recurrence of capacitor bank fires
The site had already experienced a similar fire in 2012. In addition, other similar cases over the last three years (2016-2015-2014) on the premises of other operators had been identified in the ARIA database. The operator asked its supplier to perform a technical assessment of the banks involved.
The manufacturers provided no information regarding the service life of the capacitor banks. The weekly inspection had been performed that very morning by an external service provider, and no anomalies were found (visual examination and thermographic inspection).
Measures taken
As the verification measures do not guarantee fire prevention, the company’s insurer requested that the following actions be taken:
- separate the capacitor banks from the main low-voltage switchboards and to put them aside;
- separate the banks from the high-voltage transformers;
- install smoke detectors in the high- and low-voltage substations.
The manufacturer continued the annual maintenance of the capacitor banks. In order to avoid the spread of fire throughout the company, the possibility of moving the capacitor banks into a dedicated room was studied. For those which cannot be moved, plans have been made to install an automatic extinguishing system.
