Energy distribution – Electrical energy

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Content – Energy distribution


The distribution system is the final stage in the delivery of electric power; it carries electricity from the transmission system to individual consumers. Distribution substations connect to the transmission system and lower the transmission voltage to between 2 kV and 135 kV with the use of transformers.

Primary distribution lines carry this power to distribution transformers located near the consumer premises. Distribution transformers again lower the voltage to the utilization voltage of household appliances and feed several customers through secondary distribution lines at this voltage. Commercial and residential customers are connected to the secondary distribution lines through service drops. Customers demanding large amount of power may be connected directly to the primary distribution level or the subtransmission level.

Conductors for distribution are carried on overhead pole lines or buried underground. Urban and suburban distribution is normally done with three-phase systems to serve residential, commercial and industrial loads. Distribution in rural areas sometimes is single-phase.

There are primarily two types of electrical dirtribution systems used that is radial distribution or network distribution. A radial system is arranged such that each customer has one source of supply. In a network system there are multiple sources of supply operating in paralle, mainly used in dense populated areas.

Within these networks there may be a mix of overhead line construction utilizing traditional utility poles and wires or underground construction with cables and indoor or cabinet substations.

Long feeders experience voltage drop requiring capacitors or voltage regulators to be installed.

Most public electricity supplies are single phase, two phase or three phase, 50 or 60 Hz Alternating current (AC).