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LIGHTNING PROTECTION USING LFA-M

Submitted By:Somi.P.Chacko Class : S7-EEE Roll no : 4344 MCET

CONTENTS• INTRODUCTION• LIGHTNING• TYPES OF LIGHTNING STROKES• LFA PRINCIPLE • DESIGN OF LFA-M• PROTECTION AGAINST DIRECT LIGHTNING STROKES• CRITICAL GRADIENT• EFFICIENCY OF LFA-M• ADVANTAGES• APPLICATIONS• FUTURE EXPANSION• CONCLUSION• REFERENCE

INTRODUCTION• Outages of overhead power lines due to lightning

strokes are one of the main causes of shortages of electric supplies and economic losses of power utilities

• To prevent arc fusion of insulated conductors,pole top arresters are used

• The main problem of using pole top arresters is their high cost

• LFA consists of a long surface flashover discharge element called Long Flashover Arrester(LFA)

• It is simple, effective, inexpensive and reliable• No power arc follow occurs

LIGHTNING• An electrical discharge:- 1)between cloud and earth

2)between cloud

3)between charge centres of the same cloud

TYPES OF LIGHTNING STROKES

• Indirect stroke• Direct stroke

STROKE-A

STROKE-B

DIRECT STROKES

LFA PRINCIPLEProbability of PAF depends on *mean gradient of operational voltage(E) *nominal voltage of he line(U) *length of the flashover path(L) *moment at which lightning stroke occured *lightning current magnitude *line parameters

- The LFA’s length may be several times greater than that of an insulator - The LFA impulse flashover voltage is lower than

that of the insulator and the LFA will flashover before the insulator

E=U ph / L

DESIGN OF LFA-M

LFA 10-M arrester for protection of 10 kV transmission overhead lines.

Block diagram

Electric Schematic

PROTECTION AGAINST DIRECT LIGHTNING

STROKES

CRITICAL GRADIENT

EFFICIENCY OF LFA-M

n0=NDLS P(l1) Parc (1-Prc)

n0‘=NDLS P(I1’,cr) Parc (1-Prc)

K=n0/ n0‘= 1/ P(I1’,cr)

ADVANTAGES

• Construction is simple• Reliable• Inexpensive• No power arc follow• Used for both induced overvoltages and direct

lightning strokes• No need for maintainence

APPLICATIONS• LFA-L Loop 1.cable loop 2.clamp 3.steel structure 4.metal tube 5.power line conductor 6.flashover channel 7.insulator 8.intermediate ring electrodes

• LFA Insulation tube1.power line conductor2.insulation tube3.metal tube clamp4.Insulator5.Structure6.Flashover channel7.Sparkover horn8.S-sparkover gap

FUTURE EXPANSION

• The number of flash over modules increases by increasing the cable pieces

• This can be used for lightning protection of very high voltage lines.

CONCLUSION

• LFA comprising three flash over modules, using the creeping discharge effect.

• The LFA-M is a simple, low weight and convenient apparatus.

• The cost of LFA’s is only about one tenth of that of metal oxide arresters.

• Installation of LFA’s at each pole and phase is more attractive than for metal oxide arresters

REFERENCES• George V. Podporkin, Vladimir E Pilshikov, Alexander D. Sivavev,”lightning

protection of Medium Voltage Overhead Lines by Modular Long-Flashover Arrester”, IEEE Transaction on Power Delivery, Volume 18, No 3, on pages 781-787, July 2003

• George V. Podporkin, Alexander D. Sivavev, ”lightning protection of Distribution lines by LFA”, IEEE Transaction on Power Delivery, Volume 13, No.3, On pages 814-823, July 1998

THANKYOU

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