Guidelines for Rural and Urban distribution

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Guidelines for Urban Electrification
  1. Survey the area to be supplied with electricity for existing layout of streets etc. Plot the map
  2. Predict the load using load forecasting techniques including their magnitude, time of occurrence, maximum demand and location.
  3. Sort out the types of load into residential, commercial, and industrial. Also separate the areas into corresponding types.
  4. Figure out the type of distribution to be used by determining the load densities.
  5. Check the source of power supply available in the vicinity, and the voltage of transmission grid system nearby.
  6. Locate the transmission substation and choose the voltage of sub-transmission.
  7. Locate main distribution substations, to step down sub-transmission voltage to primary distribution voltage (11, 6.6 or 3.3 Kv).
  8. Find total load of each type in the separate areas. Using demand and diversity factor find out expected maximum demand in the areas.
  9. Choose the capacity and location of transformers in the main distribution substation.
  10. Choose the size of conductor and show the layout on the map. Check if the voltage drop is within the permissible limit.
  11. Show the loads in each area on the map and sub-divide the area indicating approximately the center of gravity of the loads in sub areas. Locate the transformer near the load centers as far as possible to step down 11 Kv to 400/220 v. Choose appropriate transformer size. Find out the substation layout.
  12. Choose the size of secondary distribution conductor, type of system (radial, loop, network)
  13. Keep provision for future expansion.
  14. Choose location and size of compensating capacitors if required.
  15. Check the economic aspect the system.

Guidelines for Rural Electrification
  1. The objective of rural electrification is to supply consumers with long lines with low load density. So construction should be least expensive, durable and reliable.
  2. Predict the loads in the area. Also study the sparsity of load.
  3. Choose the type of electric supply. A single phase supply for mains supplemented by three phase supply available nearby is sometimes used for rural electrification. This makes the distribution system economical and at the same time reliable.
  4. The maximum voltage regulation at any service entrance should of not exceed 10%.
  5. Quite often,rural electrification projects have to be initially subsidized by the government to reduce the cost of energy to rural consumers.
  6. Choose voltage level of the line and conductor size. Normally 11 Kv HT lines are used for primary distribution using ACSR conductor while 400/230 v 3-phase 4 wire LT supply is given to consumers. LT lines use all-aluminum conductors.
  7. Choose the location of transformer sub-station, its size and length of feeders.

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