![]() And each doubling of voltage would allow a given cable to transmit the same amount of power four times the distance than at the lower voltage (with the same power loss). Both were supplanting gas lighting systems, with arc lighting taking over large-area and street lighting, and incandescent lighting replacing gas lights for business and residential users.ĭue to the high voltages used in arc lighting, a single generating station could supply a long string of lights, up to 7 miles (11 km) long. The first power-distribution systems installed in European and US cities were used to supply lighting: arc lighting running on very-high-voltage (around 3,000 V) alternating current (AC) or direct current (DC), and incandescent lighting running on low-voltage (100 V) direct current. Before that, electricity was usually generated where it was used. ![]() History įurther information: History of electric power transmission The late 1870s and early 1880s saw the introduction of arc-lamp lighting used outdoors or in large indoor spaces, such as this Brush Electric Company system installed in 1880 in New York City.Įlectric power distribution didn't become necessary until the 1880s when electricity started being generated at power stations. The final circuit in an urban system may be less than 15 metres (50 ft), but may be over 91 metres (300 ft) for a rural customer. ![]() The power comes to the customer via a service drop and an electricity meter. Ĭloser to the customer, a distribution transformer steps the primary distribution power down to a low-voltage secondary circuit, usually 120/240 V in the US for residential customers. Rural distribution is mostly above ground with utility poles, and suburban distribution is a mix. Urban distribution is mainly underground, sometimes in common utility ducts. The bus distributes power to distribution lines, which fan out to customers. From the transformer, power goes to the busbar that can split the distribution power off in multiple directions.These are medium voltage circuits, usually 600–35 000 V. Transformers step down transmission voltages, 35 kV or more, down to primary distribution voltages.Circuit breakers and switches enable the substation to be disconnected from the transmission grid or for distribution lines to be disconnected.The transition from transmission to distribution happens in a power substation, which has the following functions: The voltages and loadings are typical of a European network. Customers demanding a much larger amount of power may be connected directly to the primary distribution level or the subtransmission level. Commercial and residential customers are connected to the secondary distribution lines through service drops. Often several customers are supplied from one transformer through secondary distribution lines. Distribution transformers again lower the voltage to the utilization voltage used by lighting, industrial equipment and household appliances. Primary distribution lines carry this medium voltage power to distribution transformers located near the customer's premises. Distribution substations connect to the transmission system and lower the transmission voltage to medium voltage ranging between 2 kV and 33 kV with the use of transformers. Electricity is carried from the transmission system to individual consumers. Final stage of electricity delivery to individual consumers in a power grid A 50 kVA pole-mounted distribution transformerĮlectric power distribution is the final stage in the delivery of electricity.
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