A distribution system has an electrical substation which transfers power from a transmission system to a distribution system of a specified area or location. The electrical substation of a distribution system hereinafter referred to as a distribution substation provides power at a voltage suitable for intermediate or local distribution. The distribution substation essentially includes power switches which include components such as circuit breakers, isolators, etc., and power equipment which include instrument transformers constituting current transformer and/or voltage transformer, and distribution transformer. The power switches are generally used for switching on and isolating electrical equipment. It is required to de-energize the equipment to allow working on the equipment. It also clears the faults that may arise downstream.
The distribution substation is generally mounted outdoor and insulated by air, when such distribution substation involves medium and high voltages. The power switch components and power equipment in a distribution substation are mounted in outdoor on individual structures supporting them. This outdoor mounting tends to occupy more space, unlike a Gas Insulated Switchgear (GIS) which is characterized by indoor mounting and gas insulation, which occupies comparatively lesser space. The space that an outdoor distribution substation occupies becomes crucial when such distribution substation is to be located in a city, where availability of land is a concern or in a hilly region, where an almost flat surface for accommodating the distribution substation becomes one of the most considerate requirements. This greatly influences the cost of the land required for installing such distribution substation. A GIS, although it occupies less space, has a limitation regarding the scope for expansion of the substation and is not economical for outdoor medium voltage levels, due to higher equipment cost. In general, the distribution substation mounted outdoor is still a preferred solution with regard to the operating voltage level, scope for substation expansion and comparatively lower cost. Hence, there is a desire for an outdoor distribution substation which occupies less space and inherits all the characteristics of the outdoor mounted distribution substation.