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Power Generation and
Distribution
Thomas K P
Assistant professor EEE
RSET
Distribution System
Distribution system is that part of power system
which distributes power to the consumers for
utilization. The transmission and distribution
systems are similar to human circulatory
system. The transmission system may be
compared with arteries in human body and
distribution system with capillaries.
In general part of power system which
distributes electrical power for local use is
known as distribution system. Distribution
system is the electrical system between the
substation and the consumer meters ;consists
feeders ,distributors and service mains.
Distribution System
Feeder: A feeder is a conductor which connects
the substation to the area where power to be
distributed. Generally ,no tappings are taken
from the feeder. So that the current in it remain
the same throughout. The main consideration
in the design of a feeder is the current carrying
capacity.
Distributor: A distributor is a conductor from
which tappings are taken for supply to the
consumers.
Service mains: A service mains is generally a
small cable which connects the distributor to
the consumers terminals.
Classification of Distribution
System
A distribution system may be classified
according to
Nature of current : DC and AC distribution
system
Types of construction: Overhead and
underground system
Scheme of connection: Radial ,ring main and
inter-connected system
A C Distribution System
AC distribution is divided in to
Primary distribution system
Secondary distribution system
DC distribution is divided in to
2 wire DC system
3 wire DC system
Methods of obtaining 3 wire DC
system
Two generator method
3-wire DC generator
Balancer set
Overhead versus Underground
system
Public safety
Initial cost
Flexibility
Faults
Appearance
Fault location and repair
Current carrying capacity and voltage drop
Useful life
Maintenance cost
Interference with communication circuits
Connection schemes of
distribution system
Radial System: In this ,separate feeders radiate
from a single substation and feed the
distributors at one end only. The radial system
is employed only when power is generated at
low voltage and the substation is located at the
centre of the load.
Advantages: Simplest and lowest initial cost.
Disadvantages: The end of the distributor nearest
to the feeding point will be heavily loaded, Less
reliable and the consumers at the distant end
of the distribution would be subjected to
serious voltage fluctuation
Connection schemes of
distribution system
Ring main system: The primaries of
distribution transformers from a loop. The
loop circuit starts from the substation busbars, makes a loop through the area to be
served, and return to the substation.
Advantages: There are voltage fluctuation at
consumers terminals and the system is very
reliable.
Connection schemes of
distribution system
Interconnected system: When the feeder ring
is energised by two or more than two
generating stations or substations, it is
called inter-connected system.
Advantages : it increase the service reliability
and efficiency.
Requirement of a Distribution
system
Proper voltage
Availability of power on demand
Reliability
Design consideration in
Distribution system
Good voltage regulation of a distribution network
is probably the most important factor
responsible for delivering good service to the
consumers.
Feeders: A feeder design from the point of view
of its current carrying capacity while the
voltage drop consideration is relatively
unimportant.
Distributors : A distributor is designed from the
point of view of the voltage drop in it.
Types of DC Distributors
The DC distributors are classified based on
the way they are fed by the feeders.
Distributor fed at one end
Distributor fed at both ends
Distributor fed at the centre
Ring Distributor