in this presentation i have completely described the basic constriction and working of Surge Arresters so that you will find it easy to understand and it can be easily delivered to the listeners

2. SURGE/ LIGHTENING
ARRESTERS
DELIVERED TO
SIR WAQAS JAVAID

3. GROUP INTRODUCTION
• ATEEQ-UR-REHMAN (2013-EE-528)
• MUHAMMAD FAISAL IKRAM (2013-EE-516)
• FAISAL SATTAR (2013-EE-501)
• AYESHA KHAN (2013-EE-539)

4. CONTENTS
• Introduction of Surge Arresters
• Introduction of lightening
• Lightening protection
• Construction of Surge Arresters
• How does Surge Arresters works?
• Uses of Surge Arresters
• Types of Surge Arresters

5. INTRODUCTION OF SURGE ARRESTERS
• What is SUGRE ?
• A surge is basically a very High voltage which suddenly acts on
a transmission line just like lightening which fall on a
transmission line or any where else.
• And these surge arresters are not actually the policeman to
catch the surge or lightening.
It is basically a device

6.  When a voltage surge is created, it wants to equalize itself .
 The method of providing maximum protection for equipment is quite simple.
Create a pathway for the voltage surge (electricity) to get to and into the ground
outside your house as quickly as possible.
 The first step is simple. Create an excellent grounding system for your household
electrical system. Many homes have a single grounding rod and /or a metallic
underground water pipe which are part of the electrical grounding system.
 The second step in household surge protection is to install a lightning arrester
inside of your electric service panel. These devices can be extremely effective in
intercepting large voltage surges which travel in the electric power lines. If for
some reason you do not have a large enough grounding wire, or enough
ground rods.
 Similarly in electrical transmission line ,when surge comes to occur or
lighting phenomenon the different devices are use to diverge the surge.one
most commely used arresters.

7. OTHER DEVICES SIMILAR TO LIGHTENING
ARRESTERS
• Surge Suppressor:
This is also a surge diverter, but generally for voltages
well below 1000 volts.
• TVSS (Transient Voltage Surge Suppressor):
Again this is also a surge diverter, but generally for
voltages well below 1000 volts.

8. How do
Lightning
Arresters Protect
Power Systems?

13. LIGHTENING
 Definition of Lightening
 Significance of Lightening
 Mechanism of lightening discharge
 Keraunic Level
 Types of Lightening
 Effect of Lightening
 Protection against Lightening.

14. INTRODUCTION OF LIGHTENING
• What is Lightening?
• An electric discharge between
cloud and earth, between
clouds or between the charge
centers of the same cloud is
known as lightning.
• Lightening is a huge spark that take
place when cloud is charged to such a
high potential that dielectric strength
of air is destroyed.

15. INTRODUCTION OF LIGHTENING
132KV TRANSMISSION LINE
WITHOUT SURGE ARRESTERS
132KV TRANSMISSION LINE
WITH SURGE ARRESTERS

16. OVER TO
Faisal Sattar

17. MECHANISM OF LIGHTENING DISCHARGE
• Lightening discharge is
initiated by a streamer from
the cloud which progress
towards the earth in series of
steps called Stepped Leader.
• Streamer moves from earth
towards cloud is called Return
Streamer.
• Leader streamer and return
streamer has opposite charge.
• When Leader streamer and
return streamer meets one
another then a short circuit is
established between earth and

18. KEY POINTS ABOUT LIGHTENING
DISCHARGE
• A lightning discharge usually made up of a number of separate
strokes.
• 87% of all lightening strokes results from negatively charged
clouds.
• 13% of all lightening strokes results from positively charged
clouds.
• Through out the world nearly 100 lightening strokes occur per
second
• Lightening discharge current range from 10kA to 90kA.

19. KERAUNIC LEVEL
• It is defined as the average number of days per year when
thunder can be heard in a given area.
• The keraunic number has been used to set standards for safe
design of electrical systems in structures connected to the local
power grid.
• The annual number of lightning flashes hitting one square km
of ground, Ng, can be calculated from the following formula
• Td is the keraunic number.

20. TYPES OF LIGHTENING STROKES
A lightning stroke is defined as a
direct stroke if it hits either the
tower or the shield wire or the
phase conductor.
Cloud will induce a charge of
opposite polarity on lines when
potential b/w cloud and line
exceeds the breakdown value of
air discharge occurs.
Direct stroke

21. TYPES OF LIGHTENING STROKES
• Indirect stroke results from the
electrostatically induced charge
on the conductor due to presence
of charged clouds
• Induced charge leaks slowly to
earth via insulators.
• Induced charge moves in both
direction in the form of travelling
waves.
• Most of the surge in
transmission line is caused by
indirect stroke.
• Indirect stroke

22. EFFECTS OF LIGHTENING
• Traveling waves
• Insulator damage
• Transformer damage
• Lightening discharge constitute the main cause of non-
programmed outages of electrical system.
• 65% line outages originate from Lightening strokes
• Surges produced by Lightening are not felt by most of the
industrial equipment e.g. computers, Aluminum and steel mills
.

23. EFFECTS OF LIGHTENING

24. PROTECTION AGAINST LIGHTENING
• Earthing screen.
• Overhead ground wires
• Lightening Arresters

25. EARTHING SCREEN
• Earthing screen provides protection to power stations and sub-
stations against direct stroke.
• It consist of a network of copper conductor mounted all over
the electrical equipment in the substation and power station.
• Shield is properly ground through low resistance path.
• Limitation:
• It does not provide protection against travelling
waves.

26. OVER HEAD GROUND WIRES
• Protect transmission line against direct stroke.
• Ground wires are placed above line conductors in such a way
that all lightening strokes are intercepted by them.
• Tower rises potential is given by
Vt= I.R
• Vt less than insulator flashover then no trouble occur
• Tower footing resistance must be very low.

27. OVER HEAD GROUND WIRES

28. OVER HEAD GROUND WIRES
• An effective shielding
requires a strategic
positioning of earth wires so
that lightning stroke reach to
earth wires or ground.
• Most favorable position is
obtained when circle around
earth wire and conductor
meat at same point on
horizontal line.

29. OVER HEAD GROUND WIRES

30. LIGHTNING ARRESTERS
• Provide protection against direct as well as indirect stroke
• Protect power station and Transmission line

31. EARTHING IN VIEW OF LIGHTENING
PROTECTION
• Tower Earthing resistance and surge impedance is an important
parameter in determination of lightening flashover.
• Earthing resistance is a variable quantity.
• Depend upon soil and non linear conduction of earth
• Even if constant stroke current pass it changes
with time.

32. EARTHING IN VIEW OF LIGHTENING
PROTECTION

33. OVER TO
Muhammad Faisal Ikram

34. CONTENTS
• Lightening Rod
• Classes of Surge Arresters
• Working of lightening Arresters
• Surge arrester in Transformer
• Surge arrester in Transmission line.
• Short circuit test
• What is MOV?
• How does dose current flows in Arresters

35. LIGHTENING ROD
• A lightning rod or lightning
conductor is a metal rod or
metallic object mounted on top
of an elevated structure, such
as a building, a ship, or even
a tree, electrically bonded using
a wire or electrical conductor to
interface with ground or
"earth" through an electrode,
engineered to protect the
structure in the event
of lightning strike

36. LIGHTENING ROD
• Surge arresters is not a
lightening Rod although it
does the same operation that
the lightening do.
• But its construction and
working principle is very
different from the lightening
Rod.

37. CLASSES OF SURGE ARRESTERS
• Station Class
• Intermediate Class
• Distribution Class
• Secondary Class

38. WORKING OF SURGE ARRESTERS
• Normal Operation
• Occurrence of High
Voltage
• Function as a non linear
resistor

39. SURGE ARRESTERS IN TRANSFORMER
• Surge Arresters are used in
transformer both at
transmission level and at
distribution level.
• The rating of arresters used
at these are different because
of voltage levels.

40. SURGE ARRESTERS IN TRANSFORMER

41. SURGE ARRESTERS IN TRANSMISSION LINE
• Surge Arrester is also
used in Transmission
system just for the same
and basic purpose which
is the safety of our
equipment's and also the
transmission line

42. SHORT CIRCUIT TEST OF ARESSTER
• Before the installation of
surge arrester many test are
applied on this to mark it as
verified.
• One of them is short circuit
test
• In this surge arrester is
introduced to very high
voltage surge and check
weather It can bear it or not.

43. SURGE ARRESTERS (BASIC CONSTRUCTION)
• Surge arresters is consist of MOV
discs.
• What is MOV?
• MOV is Metal Oxide Varistor.
• The most common type
of Varistor is the Metal-Oxide
Varistor (MOV). This type
contains a ceramic mass of
zinc oxide grains, in a matrix of
other metal oxides (such as
small amounts of bismuth,
cobalt, manganese) sandwiched

44. SURGE ARRESTERS (BASIC CONSTRUCTION)
• The basic structure of surge
arresters is consist of MOV
discs which basically acts as a
semiconductor for normal
voltages but when a surge
appears or comes it becomes
a conductor and provides a
short path to the ground to a
very high voltage surge.
Metal
Oxide
Discs

45. THE MOV DISK
• The MOV disk is a very fast
acting electronic switch
• It is an open switch to standard
system AC voltage and a close
switch to lightening voltages.
• By magnifying the MOV material
5000 times, Metal Oxide Grains
and Dopants in the material can
be discerned
• Each MOV Disk with a 35mm
diameter and a 35mm height
contains about 28 Billion MOV

46. The MOV Grains and their Junctions are the Electronic
Switches that turn on and off in unison to divert the
lightning around the equipment.

47. A lightning arrester is essentially a collection of billions of
microscopic junctions of Metal Oxide Grains that turn on and
off in microseconds to form a current path from the top
terminal to the ground terminal of the arrester.

48. So there you have it.
A Lightning Arrester
is a device, used on
power systems, that
contains billions of
electronic switches
that divert lightning
around sensitive
equipment and saves

49. OVER TO
Ayesha Khan

50. TYPES OF SURGE ARRESTERS
• Rod Gap Arrester
• Horn Gap Arrester
• Multigap Arresters
• Expulsion Type Arrester
• Valve Type Arresters

51. ROD GAP ARRESTER
• Simple type of diverter.
• Consists of two 1·5 cm rods.
• The distance between gap
and insulator must not be less
than one-third of the gap
length.
• Due to its limitations, Rod-gap
arresters are used only as ‘Back
up’ protection.

52. ADVANTAGES DISADVANTAGES
• Under normal operating
conditions gap remains non-
conducting.
• On the occurrence of a high
voltage surge on the line, the
gap sparks over and the
surge current is conducted to
earth.
• Rods may melt or get
damaged.
• The climatic conditions affect
the performance of rod gap
arrester.
• The polarity of the surge also
affects the performance of
this arrester.

53. HORN GAP ARRESTERS
• Consists of two horn shaped
metal.
• Horn is connected to the line
through a resistance R and
choke coil L.
• Choke does not allow the
transients to enter the
apparatus to be protected.

54. ADVANTAGES DISADVANTAGES
• The arc is self-clearing.
• Series resistance helps in
limiting
the follow current to a small
value.
• The bridging of gap can
render the device useless.
• The setting of horn gap is
likely to change due to
corrosion or pitting.
• Time of operation is
comparatively long.

55. MULTIGAP ARRESTER
• It consists of a series of
metallic (generally alloy of
zinc) cylinders.
• Cylinders are separated by air
gap and are connected with
series and shunt resistances.
• Such arresters are applied
where voltage does not
exceed 33kV.

56. ADVANTAGES DISADVANTAGES
• They have the lowest let-
through voltage and the best
controlled clamping behavior
of the various arrestor types.
• It provides safety and
prevents damage to
expensive equipment.
• Their current handling
capabilities are the smallest
of all.
• Such arresters can be
employed only where system
voltage may not exceed
33kV.

57. EXPULSION TYPE ARRESTERS
• This type of arrester is also
called ‘Protector tube’.
• Commonly used on system
operating at voltages up to 33
kV.
• It essentially consists of Rod
Gap, Upper Electrode and Lower
Electrode.
• One expulsion arrester is placed
under each line conductor.

58. ADVANTAGES DISADVANTAGES
• They are not very expensive.
• They are improved form of
rod gap arresters.
• They can be easily installed.
• They can perform only limited
number of operations.
• it is not suitable for the
protection of expensive
equipment.
• This type of arresters cannot
be mounted in an enclosed
equipment.

59. VALVE TYPE ARRESTERS
• They are extensively used on
systems operating at high
voltages.
• They incorporate non-linear
resistors
• It consists of two assemblies
• Series spark gaps
• Non-linear resistor discs.
• The non linear elements are
connected in series with the
spark gap.

60. ADVANTAGES DISADVANTAGES
• They provide very effective
protection (especially for
transformers and cables)
against surges.
• They operate very rapidly
• They fail to check the surges
of every steep Wave.
• Their performance is
adversely affected by the
entry of moisture into the
enclosure.

61. APPLICATIONS OF VALVE TYPE ARRESTERS
• According to there applications valve type arresters are
classified as Two types
• Station type: Generally used for protection of equipment in
power stations operating on voltages upto 220kV or higher.
• Line type: Are used for station handling voltages upto 66kV.