This document describes a reduced-scale model that was created to study surge characteristics on a transmission line system. The model includes two tower models and a gantry model to represent the portion of transmission line coming into a substation. Experiments were conducted by injecting a steep current wave into the top of the first tower model. Voltages were measured at various points with and without a back-flashover occurring. The results provide insight into how lightning-induced surges propagate and the voltage waveforms that appear at the tower and gantry sections.

1. BY
B.BALA CHANDRA
134G1D0701
Under The Esteemed Guidance of
Ms.S.HEMALATHA, M.Tech.,
Assistant Professor
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
SRINIVASA RAMANUJAN INSTITUTE OF TECHNOLOGY
(Affiliated to Jawaharlal Nehru Technological University,
Ananthapuramu)
Ananthapuramu

2. Objectives.
Introduction.
Reduced-scale model.
Measurement positions.
Surge charactertics.
conclusion.
2

3.  Reduced-scale model to clarify the surge characteristics of conductor
system.
 This will be done with and without the presence of a back-flashover, and
the voltage generated at the tower and gantry sections at the substation
3

4.  The lightning protection design of a power station and
substation is based on standard lightning stroke conditions,
where a lightning stroke to the top of the first tower occurs to
generate a back-flashover at the upper phase and a surge
intrudes into a power station or substation.
4

5. An electric
discharge between cloud and earth,
between clouds or between the charge
centres of the cloud is known as
“lightning”.
5

6.  Lightning surge:
A transient disturbance in an electric circuit due to lighting.
Voltage Surge:
A sudden rise in voltage for a very short duration on the power
system is known as a “voltage surge”.
 Surges are temporary in nature and exist very short duration of time.
4

7. fig: a fig: b
6

8.  This model is used at the portion of the transmission line coming into the substation.
 There are two models
 1)Two tower models and
 2)gantry model ..
Tower model:
7
•In this model L-shaped section columns used for
the tower arms and feet and rectangular section
columns for the others.
•First tower arms and power lines were insulated
by Acrylic members and power lines were
grounded to the tower arms at the second tower.

9.  In this model power lines are
anchored via insulating material
and the terminals were open.
 Two lines of overhead ground
wires which are connected to the
top of the tower and gantries.
8

10. 9

11.  The steep current wave was injected to the top of the tower from the
remote pulse generator via coaxial cable.
 The coaxial cable was connected to the top of the tower.
 The phenomenon of lightning return stroke current flowing vertically from
the top of the tower .
 zero potential line is used to measure the voltage of the tower section was
arranged vertically to both tower model and line directions.
10

12. 11

13.  Inflowing current to the top of the first tower
 Potential of the first-tower arm
 Potential of power line at the first tower
 Voltage of the first-tower insulator strings
 Potential of the overhead ground wire and power line at the gantry
12

14. In the case of no flash over:
Fig:1 Injected current waveform at the Top of the tower
Fig:2
Fig:3 Upper phase power line potential at the gantry
13

15.  Injected current flows into the upper phase of the power line , a voltage of
positive polarity is generated in the upper phase of the power line in both
tower and the gantry.
Fig: surge voltage waveforms on the power line where
flashover occurs
14

16. A reduced-scale model of transmission line
imitating the range from the gantry to the second tower was set up to
investigate surge propagation characteristics on incoming lines.
It will be conducted with and without a back-flashover
to show the characteristics of the voltage waveform appearing at the tower
and gantry.
15

17. 16