Switchgear: retrofit, refurb or replace?-the asset manager's dilemma. An Rec's point of view

Midlands Electricity plc (UK) has over 46,000 units of 11 kV switchgear of which some 70% is situated in outdoor substations. The policy for asset replacement of distribution-type switchgear is based initially on an attributed life of switchgear. Location of switchgear is taken into consideration with a different attributed life given to indoor and outdoor located switchgear. Additional parameters are added to this initial base which alter the attributed life of certain types of switchgear. These parameters are based on the "in-service" experience of the switchgear.