Pollution
Humain
Environnement
Economique

At around 5 a.m., an explosion occurred on the HV transformer supplying a oven in an alloy factory. The oven was shut down due to overcurrent. The central insulator of the transformer on the furnace side exploded, causing the associated lightning arrester to malfunction, generating a fire on the insulator. Pieces of porcelain were thrown several meters away. The oil in the compensator heated up and the Plexiglas window for observing the oil level melted. The oil was released into the retention basin and ignited, causing a fire. The other two lightning arresters and insulators also failed due to the heat. Electrical cables and the transformer control cabinet were burnt out, and the oil circulation pumps began to heat up.

The emergency services used foam to quickly put out the fire at around 6 a.m. The oil was pumped out and removed by a specialised company. The transformer was dismantled and replaced, and the oven was able to be restarted the next day.

The damage to the connector due to the ageing of the oil-soaked paper used as insulation was considered to be the cause of the accident. The paper no longer acted as a capacitor. The connector, which then charged to a very high voltage beyond the construction limit, exploded.

The operator has planned to conduct thermography tests on all connection heads and an additional check for those equipped with oil-impregnated paper insulation. A fire drill with the assistance of the fire brigade was also planned.