The C and D ranges of equipment were introduced in the early 1950’s and instantly became a recognised product all over the world. There are tens of thousands of units installed on networks of 13.8kV and below, with short circuit levels of up to 43kA.
Continuous current ratings of up to 2400A were available and units could be in single busbar or double busbar configuration.
There were two distinct types of unit – the narrower “high type” non-integrally earthed unit and the wider “low type” integrally earthed unit
Whilst the 1950’s switchgear utilised porcelain bushings and SRBP bushings, the 1960’s saw a rapid conversion to cast resin insulation on the switchgear fixed portion and after a proven fifty year history, has shown no degradation in these materials at all.
Employing the C & D series of ocb’s, there were considerable variants on each rating – for example,C4X, C4X1, D4X, D4E, D4XD and many other variants for the 400A ocb alone. It is imperative that the rating of each variant is understood if network configurations or fault levels change. There are a variety of ocb internal assemblies and mechanisms utilised – dependant on user specification, vintage, operational duty and fault level requirements.
Switchgear Support Ltd are one of the leading authorities on the C and D ranges of equipment, with a complete and concise understanding of all variants, and can provide total support for these products and improvements/upgrades where necessary, including :