WELCOME LIGHTNING PROTECTION USING LFA-M Submitted By:Somi.P. Chacko Class: S7-EEE Roll no: MCET CONTENTS. Presentation on theme: “LIGHTENING PROTECTION USING LFA-M”— System ”-A system of lightning protection conductors lightning rods -installed on the. effective and inexpensive method for lightning protection of medium voltage overhead distribution line is using long flashover arresters (LFA).

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Topics For Seminar Back to the top. The cable pieces are arranged so as to form three flashover modules 1,2,3 as shown in figure1. At instants t 4t 5and t 6 the first, third, and second modules of arrester LFA B flash over, respectively, changing the resistance of the arrester. Its resistors assure application of the total arrestor-stressing voltage simultaneously to all the modules. Charge on the cloud Q is bound by cloud R. When the central part of the arrester flashes over at instant t 3the arrester sparks over through a single spark channel of very low resistance.

In stroke B the lightning discharge occurs on the overhead line as the result of stroke A between the clouds.

It keeps increasing at a still slower rate until time t 3. The induced positive charge leaks slowly to earth.


Thus the total voltage is applied to each flashover module at the same moment, and all the three flashover modules 1, 2 and 3 are assured conditions for simultaneous lfaa-m of creeping discharges which,with respective modules flashed over, develop a single long flashover channel.


If the cloud P shift too nearer to cloud Q,Then lightning discharge will occur between them and charges on both these cloud disappear quickly.

The above calculation does not take into account the effect of near-by poise: First, the line parameters are entered, including the arrangement and radius of the conductors, the pole height, the grounding resistance, etc.

The equivalent EMF e is calculated as follows. Therefore, this new lightning protection system is thought to feature simple design, low cost, and high reliability. The average span length I span of a kV line is usually about 70m.

If only a partial flashover of the arrester occurred. In direct stroke, the lightning discharge is directly from the cloud to the an overhead line. There are two main ways in which the lightning may strike the power system. Since phases B and C and their arresters operate under identical conditions, it is practical to combine them in an overvoltage analysis.

Where n 0 suing the number of lightning outages on an LFA protected line caused by direct lightning strokes on the phase conductors and P I lcr is probability of a lightning current with steepness greater or equal to I lcr The efficiency of LFA lightning protection against direct lightning strokes can be expressed as the ratio of the number of lightning outages n 0 for unprotected line to n 0 for lines protected by LFA arresters.


The rate of decrease lfam- the critical gradient slows down for larger fault currents. A new long flashover arrester model has been developed. Both results put an end to the calculation, and printout is produced. About project SlidePlayer Terms of Lightninng.

It offers great number of technical and economical advantages. The cable pieces are arranged so as to form three flashover modules 1,2,3 as shown in figure1. A long flashover arrester LFAwhich comprises of three flashover modules using protecyion creeping discharge effect, is described in this paper. For the protection of lines against direct lightning strokes, the arresters are connected between the poles and laf-m of the phase conductors in parallel with the insulators.

LIGHTENING PROTECTION USING LFA-M – ppt video online download

The rate of channel propagation on libhtning modules is determined, and the. The physical phenomena associated with a direct lighting stroke on an unprotected power line causing line tripping.

Nice seminar on Lightning Protection. Can be applied for protection of distribution lines. It is designated as LFA-M. It is stressed by fairly steep over voltage impulses associated with direct lightning strokes on a conductor. Early streamer emission Radioactive rod systems Laser induced systems Charge transfer systems.