single-phase 230 supply usually
provided for individual domestic consumers.
Power
station
25kV
Transformer
132kV to
33kV
Transformer
400kV or
275kV
to 132kV
Light industry
11kV
400V
Local garage
230V
Shops
230V
Houses
Underground distribution 400/230 volt
Underground distribution
230V
Small
offices
Overhead
transmission lines
400kV, 275kV or
132kV
Heavy industry
33kV
Transformer
33kV to
11kV
Local
sub-station
11kV to
400V
FIGURE 11.Basic Electrical Installation Work
224
Distribution the consumer
The electricity leaves the local sub-station and arrives the consumer’s
main’s intake position.4
Simplified diagram the distribution electricity from power station consumer. The star point earthed earth electrode sunk into the ground
below the sub-station and from this point taken the fourth conductor,
and the neutral.
11. The final connections are usually simple under-
ground radial feeders 400 V/230 Underground cable distribution is
preferred within city, town village because people find the overhead
distribution, which see rural and remote areas, unsightly. Loads connected between phases are fed 400 and
those fed between one phase and neutral 230 three-phase 400 V
supply used for supplying small industrial and commercial loads such as
garages, schools and blocks flats. Also, at
these lower distribution voltages, the cost underground cables not
prohibitive. The 400 V/230 derived from the kV/400 sub-station
transformer connecting the secondary winding star shown Fig.
.5
