Design and construction of 11 kV prefabricated substations for the Millennium Dome

The electricity supply to the Millennium Dome required eight 11 kV substations, to be placed in the cylinders outside the Dome, and an additional 11 kV switchboard to supply the Greenwich Peninsula development. The main requirements for the installation were: minimum site work; high security of supply; high level of safety for operators and the general public; and minimum maintenance. This paper gives an overview of the equipment design concepts, including 11 kV switchgear, enclosure and ancillary devices. Details are given of the type test carried out in a substation to ensure a high level of safety in the unlikely event of an internal arc. The benefits of applying the concept of factory built modular substations to more complex applications, such as 33 kV/11 kV primary substations, are also briefly discussed.