Mitigating the effects of arcs in M.V. switchgear

An internal arc in MV switchgear results from an insulation failure between conductor phases or between conductor phases and earth. The effects of these arcs hold significant risks to the safety of operators and members of the public who may have access to equipment installations, and to the electrical plant health and electrical plant availability. To prevent these insulation failures newer generation MV switchgear standards include more onerous type test requirements to ensure the adequate dielectric design and performance of the switchgear. However, as the risk cannot be completely eliminated, internal arc classification (IAC) could be assigned to state the behaviour in case of failure, and the tested parameters. Specific functions may also be added, designated to mitigate the effects…