13. 7. FUSES AND ISOLATING SWITCHES
They are different parts of the overhead system, the network can be isolated if necessary.
Disconnecting Switch (Isolator)
High-voltage fuse cutout applied to
alternating current system
14. 8. CONTINOUS EARTH WIRE
Tower or the poll is over the top of the line along the entire Earth trait. The unusual
circumstances created by the additional voltage Discharge line to protect the soil easily.
Protective grounding jumper installation for two-pole and three-pole structures (grounded
structures). OGW denotes overhead ground wire. OGWs must be bonded to the worksite
grounding system if within reach of linemen. OGWs may be bonded to the cluster bars or to
the grounded phase conductors with protective grounds.
15. 8. CONTINOUS EARTH WIRE
The most effective method of providing protection to transmission lines against
direct lightning strokes is by use of overhead ground wires as shown in Fig 6. For simplicity,
one ground wire and one line conductor are shown. The ground wires are placed above the
line conductors at such positions that practically all lightning strokes are intercepted by
them (i.e. ground wires). The ground wires are grounded at each tower or pole through a
low resistance as possible. Due to their proper location, the ground wires will take up all the
lightning strokes instead of allowing them to line conductors. The degree of protection
provided by the ground wires depends upon the footing resistance of the tower.
A lightning stroke hits an earth wire
16. 9. GUARD WIRE
When a power line, telephone or telegraph line crossing, and then find the
line that connects the top and bottom of the Earth Wire is used to guard.
17. 10. BIRD GUARDS
It is created on the side of the saw teeth as long
ebonite basest plate, which is a cross - is prevented in
the presence of arm insulator. The birds of hokier
cross - in the arm and conductor Flash - Over in
the out .
18. 11. VIBRATION DAMPER
vibration damper dimple shape in the presence of these
lines connect to the poll, that tremble down the line. The air
flow through the conductor is conductor vibration, the
vibration is. The pressure on the conductor in the conductor
can be read off tear. The best way to protect against
damage from vibration induced arms rod is used. Bates is
one of the Stock Bridge damper .The shaking intensity is
used to prevent damper betas.
19. 12. JUMPERS
jumpers connection is connected via the
two conductor. Nevertheless, as part of the
phase plate, Danger plate, Barbed wire,
Cradle guard. Etc.
Transmission and distribution system leak overhead line of
the by chance current can not flow, so that the line from the Earth,
the Insulator is used for the line. Insulator important role in system
Transmission line insulators are devices used to contain,
separate or support electrical conductors on high voltage electricity
supply networks. Transmission insulators come in various shapes
and types, including individual or strings of disks, line posts or long
rods. They are made of polymers, glass and porcelain--each with
different densities, tensile strengths and performing properties in
22. TYPES OF INSULATORS
There are several types of insulators but the most commonly used
are pin type, suspension type, strain insulator and shackle insulator.
23. PIN TYPE INSULATORS
As the name suggests, the pin
type insulator is secured to the cross-
arm on the pole. There is a groove on
the upper end of the insulator for
housing the conductor. The conductor
passes through this groove and is
bound by the annealed wire of the
same material as the conductor.
24. PIN TYPE INSULATORS
Pin type insulators are used for transmission and distribution of
electric power at voltages upto 33 kV. Beyond operating voltage of 33
kV, the pin type insulators become too bulky and hence
25. PIN TYPE INSULATORS
Pin type insulators are used for the transmission of lower
voltages. A single pin type insulator is used to transmit voltages up to
11 kV (kilovolts) and higher voltages require two-, three- or four-piece
pin insulators. They are not economically feasible for 33 kV and higher
Pin type insulators are secured with steel or lead bolts onto
transmission poles. These are typically used for straight-running
26. SUSPENSION TYPE INSULATORS
For high voltages (>33 kV), it is a usual practice to use suspension
type insulators shown in Figure. consist of a number of porcelain
discs connected in series by metal links in the form of a string.
27. SUSPENSION TYPE INSULATORS
The conductor is suspended at the
bottom end of this string while the other end
of the string is secured to the cross-arm of the
tower. Each unit or disc is designed for low
voltage, say 11 kV. The number of discs in
series would obviously depend upon the
working voltage. For instance, if the working
voltage is 66 kV, then six discs in series will be
provided on the string.
Suspension type transmission line insulators suspend and support
high voltage transmission lines. They are cost effective for higher
voltage transmission, typically replacing multiple pin type insulators.
Suspension type insulators have a number of interconnected porcelain
discs, with each individual unit designed to support a particular
28. Together, a system of these discs is capable of effectively supporting
high voltages. There are three types of suspension insulators:
cemented cap suspension insulators; interlinking or Hewlett
suspension insulators; and link or core suspension insulators.
SUSPENSION TYPE INSULATORS
29. ADVANTAGES OF SUSPENSION TYPE INSULATORS
1. Suspension type insulators are cheaper than pin type insulators for voltages
beyond 33 Kv.
2. Each unit or disc of suspension type insulator is designed for low voltage,
usually 11 kV. Depending upon the working voltage, the desired number of discs
can be connected in series.
3. If any one disc is damaged, the whole string does not become useless because
the damaged disc can be replaced by the sound one.
4. The suspension arrangement provides greater flexibility to the line. The
connection at the cross arm is such that insulator string is free to swing in any
direction and can take up the position where mechanical stresses are minimum.
5. In case of increased demand on the transmission line, it is found more
satisfactory to supply the greater demand by raising the line voltage than to
provide another set of conductors. The additional insulation required for the
raised voltage can be easily obtained in the suspension arrangement by adding
the desired number of discs.
6. The suspension type insulators are generally used with steel towers. As the
conductors run below the earthed cross-arm of the tower, therefore, this
arrangement provides partial protection from lightning.
30. STRAIN TYPE INSULATORS
When there is a dead
end of the line or there is
corner or sharp curve, the line is
subjected to greater tension. In
order to relieve the line of
excessive tension, strain
insulators are used. For low
voltage lines (< 11 kV), shackle
insulators are used as strain
31. STRAIN TYPE INSULATORS
However, for the high voltage
transmission lines, strain insulator consists of
an assembly of suspension insulators as
shown in Figure. The discs of strain insulators
are used in the vertical plane. When the
tension in lines is exceedingly high, at long
river spans, two or more strings are used in
32. Strain type insulators are horizontally suspended suspension
insulators. They are used to handle mechanical stresses and take the
pressure off a conductor at the end of a transmission line, at a sharp
corner or curve or over long river crossings. Strain insulators are
typically used for higher voltage transmissions
STRAIN TYPE INSULATORS
34. SHACKLE TYPE INSULATORS
However, unlike strain insulators,
shackle insulators are designed to
support lower voltages. These insulators
are single, round porcelain parts that are
mounted horizontally or vertically. In
early days, the shackle insulators were
used as strain insulators.
But now a days, they are frequently used
for low voltage distribution lines. Such
insulators can be used either in a
horizontal position or in a vertical position.
They can be directly fixed to the pole with
a bolt or to the cross arm
37. Stay insulators, also called egg insulators, are primarily used
to prevent stay wires from becoming energized from accidentally
broken live wires. They, therefore, function to provide insulation
between stay clamps and transmission poles. Stay insulators are
mounted at a height of at least 3 meters (118 inches) from ground
STAY TYPE INSULATORS