Oil filled switchgear replacement-type testing and system issues

There is a growing interest in the economic replacement of ageing oil filled switchgear. Whether whole switchboards are renewed or partial replacement is implemented the same obligation exists to achieve appropriate performance levels. Where a sub-assembly replacement is used it is necessary to consider its performance not only as a unit, but also its interaction with the main assembly. The requirements included in switchgear standards are usually found to have changed considerably since the original installation of ageing oil filled switchgear, but it is possible and essential to ensure that short-circuit, thermal, dielectric, mechanical and environmental performance requirements of the new combination of equipment are met. The type testing programme of such equipment must reflect this requirement. When making changes to the equipment or implementing a `retro-fitting´ exercise any system issues should also be addressed. Ageing switchgear may well belong to an ageing system such as in an industrial complex which may have been subject to many changes throughout its life. If such changes have been well documented, fault levels evaluated and protection co-ordination has been maintained then such a review of the system will be simple and straightforward. Successful replacement of oil-filled switchgear requires an overall strategy taking into account not only equipment but a review of the system