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Electricity substation
a facility that converts and distributes electricity. A substation consists of transformers or other conversion equipment, distribution equipment, control mechanisms and auxiliary equipment. An electrical installation or set of electrical devices that convert voltage or type of electrical current, and that distribute electricity to consumers. Substations are the intermediate link in the electricity transmission system between power stations and consumers.
Equipment employed at substations includes: high-voltage (>1,000 V) switchgear (switches, disconnectors, separators, shorting) and surge-protectors; the main converting equipment, such as electrical transformers, rectifiers, inverters and frequency converters; low-voltage (<1000 V) switchgear (circuit breakers, circuit breakers, contactors) to enable and disable consumer networks; and control panels housing manual or automatic control units and switchgear, as well as measuring instruments and hardware protecting against overloads, short-circuits and large under-voltages. In addition, substations house auxiliary equipment (batteries to power control systems, maintenance facilities, premises for inspecting the main units, dryers and facilities for regenerating transformer oil). Substations may also include equipment for increasing the power rating (static condensers or synchronous compensators). Substations attached to long-distance high-voltage transmission lines are connected via high-frequency communications equipment to control rooms, which can run them remotely over the transmission lines.
Substation equipment may be in the open air or housed inside some premises or a separate building. Small substations may house their equipment on supports made of wood, reinforced concrete or metal. Particularly promising for the future is the use of enclosed substations handling voltages of up to or more than 500 kV using compressed sulphur hexafluouride (SF6) to insulate, for example, cables and braces as well as high-voltage circuit-breakers. This type of substation is particularly convenient in large towns where space is limited and conventional exposed high-voltage facilities are not permissible.
As a rule, substations are manufactured in their entirety and installed either pre-assembled or in prefabricated sections.
