Switchgear assemblies construction requirements

In the cubicle construction of a switchgear assembly the busbar chamber is normally located at the top of the assembly and runs through the length of it. It is usually suitable for extension, through fish joints at either end, if required at a later date. For installations having top cable entry, the busbar chamber may also be located at the bottom of the assembly or the depth of the panel increased, with an additional shroud between the top busbar chamber and cable chamber. From these main busbars are tapped the vertical buses for each vertical panel. Manufacturers may adopt different practices for horizontal and vertical busbar arrangements to economize on their cost of production. We illustrate the most common types of busbar arrangements. 

Below we discuss briefly the constructional requirements and general manufacturing practices for cubicle-type switchgear and controlgear assemblies, and the electrical and the mechanical design considerations to comply with the above design parameters and service conditions. 

Low voltage switchgear and controlgear assemblies. Particular requirements for assemblies for construction sites BSEN 60439-4/1991 ... 

The above are the more obvious constructional, design and safety features for a switchgear or a controlgear assembly. For more details and additional requirements refer to lEC 60439-1 for LT, lEC 60298 and lEC 60694 for FIT and ANSI-C-37/20C, common for LT and FIT switchgear and controlgear assemblies. 

Cubicle type switchgear can be constructed in many different arrangements depending upon a variety of requirements. For example the following aspects may be important for a particular plant, environmental protection, ease of access to internal parts, ease of terminating cables, fixed or withdrawable switching devices, maintainability and level of personnel skill, cost and economics, expected life duration of the product, fitness for its purpose. The switchgear industry is very competitive and so it is essential to clearly specify what is required in the form of assembly and its construction. Otherwise a false or unsatisfactory decision may be made mainly based on a cost comparison. 

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