The functioning of nuclear power stations requires a power supply that guarantees the site’s operation and security. The system of power distribution is designed to meet the needs of the standard use of a nuclear unit when it produces power or when on standby (working auxiliaries and permanent auxiliaries) but also to ensure the power supply to the equipment providing the safety functions required during an on-site incident (assistance auxiliaries). Emergency diesel generators enable support to the safety systems of a reactor in the event of a power supply breakdown by the national network. Each nuclear reactor is equipped of two emergency diesel generators. Over and above this, an additional generator is available for all the reactors on a site. This set up is sufficient to maintain operational continuity and the supply of the system is necessary to ensure the safety of a standby reactor.
The reliability of these diesel generators is crucial. An inspection of the health of the generators is therefore performed regularly. For this reason, nuclear power station management rely on manufacturers able to design load banks capable of ensuring several megawatts, at the same time as its associated control system (measurement system, automatic cycles). These load banks are often in medium voltage.