in this article we will know about the primary distribution system, we will also studied about the main primary distribuiton system . we will also know about the secondary distribution system.
Primary distribution system
Primary distribution system is of four types-
1. Radial feeder
2. Parallel feeder
3. Loop feeder
4. Primary network
1. Radial feeder
Radial feeder system is main types of primary distribution system
This feeder is used to supply small and medium residential,
commercial loads. It radiates from the secondary substation and branches into
sub feeder and laterals which extended into all parts of service area. The
feeder and sub feeder are three phase three wire circuit. The distribution transformer
is connected to primary feeder, sub
feeder and laterals through fused cutouts.
2. Parallel feeder
It consists of duplicate feed system having two radial feeders
running in parallel. Each feeder supplies about half of total load of the area
but has a capability to supply the entire load in the event of an outage on the
other feeder. Failure of any feeder will result interruption of service until
the load normally supplied by the faulted feeder is transferred to the other
feeder by automatic control switch.
3. Loop feeder
A system of two or more radial feeders originating from the
same or secondary different substation and separately routed through load area
is known as loop feeder.it is also main types of primary distribution system.
If ends of two feeders are tied together through normally
open switching device the resulting arrangement is known as open loop system
and if ends are tied together by means of normally closed switching device the
result is a ring loop feeder.
4. Primary Network
This system consists of a number of interconnected feeders.
Two or more secondary transmission circuit supply two or more secondary
substations from which the feeder takes off. Because the feeder is
interconnected power is supplied to all the distribution transformers even
though a part of network may be out of service. Each secondary substation
consists of a transformer and the necessary switch gear to isolate the faulty
feeder and to control feeder.
Secondary distribution system
The secondary distribution system consist of three phase
four wire 400V distributors laid along road sides. The service connection are
tapped off the off the distributors at convenient points. These connection may
be 1 phase two wire circuit or 3 phase 4 wire circuit.These are basic types of primary distribution system.
Secondary distribution system
The secondary system used are-
1. Radial
2. Open loop
3. Network distribution
1. Radial system
It takes off from the distribution transformer and runs
through the area to be served by it.
2. Open loop system
This system consist of two distributors taking off from the
same distribution transformer and running in different directions and supplying
different areas at time of fault one of distributors, power can supplied through
partially, from the other distributor.
3. Network distribution
A network grid system consist of a number of inter connected
distributors. Two or more distribution transformers feed the distribution
network and operate continuously in parallel. This system is suitable for
serving high load density metropolitan areas. Which are shows in secondary
distribution system.