3.6. Distribution Systems

Oftenly it is impossible to draw a line between the distribution and transmission systems of a large power network. In general, distribution systems comprise that part of the network of a power system which distributes power for local use.

Distribution systems may be classified as follows:

1. Nature of current:

1. Direct current
   1.                                                               i.      Two wire
   2.                                                            ii.      Three wire
2. Alternating current.

2. Method of connections:

1. a.    Series
   1.                                                               i.      Open loop
   2.                                                            ii.      Parallel loop
   3.                                                          iii.      Combination of open and parallel loops
2. b.   Multiple
   1.                                                               i.      Three system
   2.                                                            ii.      Feeder and main
   3.                                                          iii.      Network
   4.                                                          iv.      Loop system
   5.                                                             v.      Ring system.
3. c.    Number of phases:
   1.                                                               i.      Single
      1. Two wire
      2. Three wire
   2.                                                            ii.      Two
      1. Three wire
      2. Four wire
      3. Five wire
   3.                                                               i.      Three
      1. Three wire
      2. Four wire
4. d.   Mounting:
   1.                                                               i.      Overhead
   2.                                                            ii.      Underground

Voltage: 115/230,550, 1100,2200,6600, 11000, 12000,13200,32000 V.