Risk management of ageing assets; Minimum oil breakers

A significant number of minimum-oil breakers has been installed in HV substations and distribution cabinets of regional network operator Stedin. E.g. 35% of all bays in HV stations. Eaton, the successor to the original manufacturers Coq and Hazemeyer intended to end the support of these breakers in 2014. The paper describes the ensuing risk evaluation, options and two-track approach chosen by Stedin to manage the risk: 1. Replacement of switchgear within a period of 20 years, 2. Conservation of the 10 - 25kV switchgear that have not been replaced, during 20 years, in cooperation with the successor to the original supplier. For conservation, a long term cooperation has been agreed upon with Eaton. For the other track, replacement, a replacement sequence is elaborated.