Surge arresters are devices used to protect electrical equipment from lightning and switching surges. There are several types including rod arresters, horn gap arresters, multigap arresters, and modern metal oxide arresters. Surge arresters work by limiting high voltages from lightning strikes or other surges to safe levels before they reach equipment like transformers. They do this using a metal oxide varistor that acts as an insulator under normal voltages but conducts at higher surge voltages, diverting excess energy to ground. This protects equipment downstream from potential damage.

1. Presented By:-
Shubham Kumar
Electrical Department

2. Surge Arresters

3. CONTENT
Introduction
Types of surge arrester
 Lightning
Surge arresters in transformer
How do surge arrester protect transformer
What exactly does a surge arrester do?
Advantage of surge arrester
Disadvantage of surge arrester

4. INTRODUCTION
SURGE ARRESTER:
 A device used on power system in high voltage line, to
protect electrical equipments from lightning and
switching surge .
 It is also called SPD or TVSS.
 It is a surge diverter.
the surge arrester should have a low impulse
ratio.

5. Types of arresters
Rod arrester.
Horn gap arrester.
Multigap arrester.
Expulsion type arrester.
 Metal oxide arrester.

6. ROD ARRESTER
Simple type of arrester.
Consists of two 1.5 cm length rod bend at right
angle.
One rod connected to line circuit and other
connected to the earth.

7. Horn gap arrester
Consists of horn shape two metal rod ,separated
by small air gap.
Distance gradually increases towards the top.
One rod connected to line through resistance and
choke coil and other to ground.

8. Multigap arrester
Consists of series of metallic cylinder.
Insulated from each other and seperated by a
small intervals of air gap.
First cylinder is connected to lines and other is to
ground through series resister.
System voltage doesn't exceed 33kV.

9. Expulsion type arrester
Consists of air gape series with 2nd air gap
enclosed within fire tube.
The gap is formed with the help of two electrodes.
Upper electrode is connected to rod gap and lower
electrode to earth.

10. Metal oxide arrester
Mostly used arrester in present time.
Without gaps.
Gapless design eliminate the high heat
association with the arcing discharge.
Utilizing ZnO blocks to provides the best
performance.

11. Lightning
When lightning strike transmission line
then a very high voltage is generated within
it.

12. How do surge arresters protect transformer or
power system
11000 Volts
230 Volts

13. Typically
11000 Volts
230 Volts

14. Typically
11000 Volts
230 Volts
Surge arrester

15. Typically
11000 Volts
230 Volts
Surge arrester

16. What exactly does a surge
arrester do?
It does not absorb the lightning.
It does not stop the lightning.
It divert the lightning to ground.
It limit the voltage produced by
lightning.
It only protects equipment electrically
in parallel with it.

19. At the Heart of all Arresters is the Metal
Oxide Varistor (MOV)
MOV disk is semiconductor disk
which is very sensitive to voltage.
At normal voltage the MOV Disk is an
insulator and will not conduct current.
But at higher voltage caused by
lightning it becomes a conductor.

20. The Metal Oxide Varistor (MOV) is a very fast acting
electronic switch.
It is an open switch to standard system AC voltage
and a closed switch to Lightning voltages.

24. Advantage of surge arrester in transformer
The surge arrester protects the transformer
and other electrical equipment from lighting
and switching surge..

25. Disadvantage of surge arrester
Conducting surge arrester blow fuses.
Surge arrester has no live line capabilities.
The earth connection should be checked
periodically.