Types of Substations

Types of Substations Points : types of substations, step-up sub-stations, primary grid sub-stations, secondary sub-station, distribution sub-station, bulk supply and industrial sub-stations, mining sub-stations, mobile sub-stations, cinematograph sub-stations Introduction: In between the power house and ultimate consumer a number of transformation and switching stations have to be created. These are generally known as sub-stations. Types of Substations Depending on the purpose the sub-stations may be classified as: 1. Step-Up Sub-Stations The step-up sub-stations are associated with the generating stations. The generation voltage is limited to a low value and needs to be stepped up to the primary transmission voltage so that huge blocks of power can be carried over long distances to the load centers economically. 2. Primary Grid Sub-Stations The primary grid sub-stations are created at suitable load centers along the primary transmission lines. The primary transmission voltage is stepped down to a number of suitable secondary voltages. 3. Secondary Sub-Station From here, secondary transmission lines are carried over to the load points. Along these secondary stepped down to sub-transmission and primary distribution voltage. 4. Distribution Sub-Station The distribution sub-stations are created where the sub-transmission voltage/primary distribution voltage is stepped down to supply voltage; these sub stations feed the actual consumers through a network of distributors and service lines. 5. Bulk Supply and Industrial Sub-Stations The bulk supply and industrial sub-stations are generally distribution sub stations with the difference that sub- station is created separately for a consumer and subsequent distribution of the electric power is left to the particular consumer of large or medium supply group as may be designated by the standards laid down by the electric supply undertaking. 6. Mining Sub-Stations The mining sub-stations; as their name indicates, are sub-stations required for very special purposes; they need special design considerations because of the extra precautions for safety needed in the operation of the electric supply. 7. Mobile Sub-Stations The mobile sub-stations are also of special purpose and designs; they are needed primarily for temporary requirements such as for construction purposes. 8. Cinematograph Sub-Stations This cinematograph sub-stations are also specific purpose sub-stations and are required to meet special requirements. Civil and Electrical Works Is a Sub-Station A modem sub-station is a complex structure as it requires numerous items of equipment and allied services. The work on a sub-station starts from the civil and electrical, survey of the area to choose the site. The ideal site for a sub-station is naturally the centre of gravity of the electrical load but in practice the cost and availability of land, access for heavy vehicles, considerations of plant installation and handling future expansion of the sub-stations etc are equally, if not more, important. After the site has been selected and land acquired the work is divided primarily into two groups’ viz., civil works and electrical works. The civil works comprise of:
(1) Buildings
(i) Residential
(ii) Non-residential (e.g., office, stores, repair, control room etc.)
(2) Railway siding and railway track and overhead cranes
(3) Design and construction of foundation and transformer plinth
(4) Cable trenches
(5) Fencing around switch yard
(6) Water supply
(7) Drainage and. sewage
(8) Roads and paths
(9) Arboriculture