Substation layout diagrams provide scale drawings of the location of each piece of
equipment in a substation, in both plan and elevation. While individual utilities may
have their own format, there is a high degree of standardisation of these types of
drawings worldwide, for contractual and tendering purposes. Figure 12.12a and b
shows the plan and elevation drawings for a typical layout of two 115-kV bays, one for
a transmission line and the other for the HV side of a local transformer, connected to a
single 115-kV busbar. The equivalent single-line diagram is depicted in Figure 12.12c.