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Protection againstovervoltage due to

lightning

PRES

AN

EEE

R

S%A&I 'I'E(ANANDA INSTIT)TE !* TEC

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IndeIntroduction

 Lightning & Adverse Effect

 Protective Devices-

a. Earth screenb. Overhead Ground wire

c. Lightning Arresterd. Recloser

• Rod ga/ A• Horn ga/ • Pellet t0/•  E/ulArrester• 'alve T0/

Conclusion

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Introduction

There are several /ossi2ilities o3 overvoltage o3 e4uthat can 2e caused 20 internal and eternal !vervoltage due to lightning is 5ore a//rec5agnitude that 5a0 get the e4ui/5ents Thence3orth the ter5 8/rotection9 co5es an/rotective devices 5ust 2e installed to contideli2eration s0ste5.

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"ightning + Adverse E7ect

"ightning is nothing 2ut an electric discharge 2et

charge centers o3 sa5e cloud6 :hich contains an charges and creates a huge voltage that har53e4ui/5ents.

In the gra/hical re/resentation6

The :ave is characteri;ed 20-

 Crest or /ea< value *ront ti5e Ti5e duration

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This stee/-3ronted :ave3or5 carries so5e adverse e7

• Travelling :ave :ill shatter the insulation

• Accu5ulation o3 charges + insulation 2rea< do:n

• !scillation o3 line

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Protective Devices

*ro5 the /revious e/lanation it is seen that the e7ect 5a0 2e 5ore ha;ardous6 disru/ts thedeli2eration /rocedure. So6 to /rotect these 3ro5 dso5e /rotective devices 5ust 2e installed. These are

 Earth Screen?

  Earth screen is 2asic and e/ensive e4ui/5/rotectors6 5ade 20 constructing a net:or< oconductors 5ounted all over the electrical e4ui/5en

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!verhead ,round %ire?

  !verhead ground :ire is installed 3or /roviding/rotection on trans5issional ele5ents and set u/a2ove the line :ires at an eact /osition :here astro

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Recloser?

That is used to detect a 3aulton line and disconnect thesection and auto5aticall0 tr0to reconnect a3ter an interval.

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"ightning Arrester?

In /revious e/lanation6 earthscreen and ground :ire can:ell /rotect the overvoltage 2utnot travelling :ave that is

o2structed 20 using lightningarresters.

In addition it is a2le to divert thehigh voltage surge to:ardsground.

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i. Rod ga/ Arrester?

ii.  Horn t0/e Arrester?

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iii. Pellet t0/e Arrester ?

This t0/e o3 arrester5ade 20 lead /eroidecoated 20 lead oide.

"ead oide is not strongconductive 6lead/eroide is.

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Co5/ound sheath non-

clearance arrester

Earl0 strea5er e5

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Conclusion

*ro5 the earlier discussion6 :e can conclud/rotection 5ust 2e needed 3or :el3are o3 /o:er s0sto /rovide endless deli2eration s0ste5. So6 these /devices should 2e /er3ect and 5ore ecient. Th5odern technolog0 is 2eing used to cut do:n vo5ai5u5 as /ossi2le.

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THAN( Y!)