During a thunderstorm, an igniter damaged an electrical station supplying in 63 kV an industrial gas plant, and in so doing deprived it of supply from 2:10 pm to 4 pm. This event also exerted an impact on a neighbouring plant manufacturing zirconium (ARIA 38391); this company had been supplied with compressed air by the first plant, but it too had to face a supply cut-off.
Before this incident, on 31st August, 2008, a re-ignition occured on one of the measurement assemblies, leading to a micro electricity outage. Inspections were carried out, but these were unable to indicate the cause of ignition. Nonetheless, it was scheduled to change all 3 measurement assemblies. The replacement lead time however was 6 months, given that the incident occurred prior to expiration. The ignition affected one of the assemblies located downstream of both the plant’s normal and backup supply connections, making the backup supply line inoperable.
Following this incident, it was initially planned to replace the single meter by meters placed on both the plant’s electrical circuits. Afterwards, supplying both circuits would be feasible by each of the plant’s supply lines (i.e. normal and backup). Securing the neighbouring plant’s compressed air supply (or the alternative option of offering this amenity via the industrial gas plant) was worthy of study for the purpose of avoiding having to operate the plant in degraded mode. Moreover, the backup electric generating set failed to start. The maintenance contract for these generating sets stipulated 2 inspections a year. An electrical cut-off test not explicitly specified in the control procedures had never been performed. It was therefore anticipated to modify the control procedure for these generating sets. The monitoring programme for key safety-related elements was to be entirely revised, and it became necessary to quickly draw up the list of equipment that required backup by the generating sets or that received an uninterrupted supply of compressed air in the event of electricity outage.
