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13.8.3 Overhead Versus Underground Distribution Systems
The distribution system can be installed through overhead lines or through
underground cables. Overhead lines are generally mounted on concrete or
steel poles. The distribution transformer (11 kV/400 V) is mounted on poles.
Supply is taken out from the secondary of the transformer through cables. In
an underground system cables are laid below the ground level along the street
by the side walk. The choice between overhead lines and underground cables
depends upon a number of factors like initial cost, ease of location of any
fault, safety consideration, maintenance cost, aesthetics, etc.
Figure 13.7 Distribution of power to industries and residential complexes
13.8.4 Connection Schemes of Distribution System
The distribution network consist of feeders, distributors, and service mains.
Feeder is a cable which feeds the distributor. From the distributor,
connections are taken to supply the consumers. Such connections are called
service mains. Two types of arrangements are made. These are called the
radial system and the ring main system. Fig. 13.8 shows the difference
