The assessment and management of aged oil-filled switchgear

When considering the future of aged (pre-1960) oil-filled switchgear, a number of factors need to be considered. This paper examines these factors together with the modes/consequences of failure and the methods/techniques of failure prevention. The alternative options for dealing with aged industrial switchgear are explored with particular emphasis on the condition assessment approach. The available diagnostic techniques are described and their advantages/limitations identified. Also covered are the importance of including condition monitoring techniques in an effective maintenance strategy and the importance of high voltage insulation assessment in determining whether to replace or refurbish inadequate switchgear. The paper is essentially aimed at industrial/commercial organisations with oil circuit breaker (OCB) switchgear operating at 11 kV and 33 kV but the content is equally applicable to OCBs operating at other voltages such as 3.3 kV, 6.6 kV and 25 kV. In addition, many of the points discussed will apply to other oil-filled switchgear such as 11 kV oil switches, 11 kV oil switch fuses (or fuse switches) and low voltage oil switchgear