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Fundamentals of Distribution Systems
Published in T. A. Short, Electric Power Distribution Handbook, 2018
Electric power distribution is the portion of the power delivery infrastructure that takes the electricity from the highly meshed, high-voltage transmission circuits and delivers it to customers. Primary distribution lines are “medium-voltage” circuits, normally thought of as 600 V to 35 kV. At a distribution substation, a substation transformer takes the incoming transmission-level voltage (35 to 230 kV) and steps it down to several distribution primary circuits, which fan out from the substation. Close to each end user, a distribution transformer takes the primary distribution voltage and steps it down to a low-voltage secondary circuit (commonly 120/240 V; other utilization voltages are used as well). From the distribution transformer, the secondary distribution circuits connect to the end user where the connection is made at the service entrance. Figure 1.2 shows an overview of the power generation and delivery infrastructure and where distribution fits in. Functionally, distribution circuits are those that feed customers (this is how the term is used in this book, regardless of voltage or configuration). Some also think of distribution as anything that is radial or anything that is below 35 kV.
Electric Machines and Power Systems
Published in Mohd Hasan Ali, Wind Energy Systems, 2017
The electric power distribution system represents the final stage in the transfer of power to the individual customers. It comprises those parts of an electric power system between the subtransmission system and the consumers’ service switches. It includes distribution substations; primary distribution feeders; distribution transformers; secondary circuits, including the services to the consumer; and appropriate protective and control devices. Sometimes, the subtransmission system is also included in the definition. The elementary diagram of a distribution system is shown in Figure 3.13.
Quantifying the seismic risk for electric power distribution systems
Published in Structure and Infrastructure Engineering, 2021
Yang Liu, Liam Wotherspoon, Nirmal-Kumar C. Nair, Daniel Blake
Electric power distribution systems deliver electricity from the transmission system to individual consumers. Transmission systems, as the backbone of national grids, are built to be strongly meshed for reliability purposes. In contrast, distribution systems are typically built as weakly meshed, radial networks, mainly due to economic constraints. Therefore, distribution systems are intrinsically more vulnerable to earthquakes than transmission systems due to lower redundancy in both network topologies and substation circuits. The performance of distribution substations are crucial to the entire distribution network performance, and a single component failure could lead to complete disconnection of the down-stream system, which is not always the case in transmission systems.