Monitoring insulating oil for fouling in load step switches involves determining cumulative spark energy, comparing with limit value, generating message if limit or percentage thereof exceeded

摘要

The method involves entering switch parameters and a permissible spark energy limit to non-volatile memory, incrementing an index (n) for every changeover, i.e. switch operation, measuring the transformer load current (IL) during switching, determining the switch currents (ISK,IWK) of the switch contact and at least one resistance contact being turned off, summing to give a total switch current, determining the spark energy (E n) and the cumulative spark energy (GE n), comparing with the limit value and generating a message if the limit or a percentage thereof is exceeded.