# LIGHTNING PROTECTION USING LFA-M PDF

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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Modules1 and 3 flashover first, followed by module 2 ,and thus, forming a rather long flashover channel along the LFA. The induced positive charge leaks slowly to earth.

The lightning protection failed. For the protection of lines against direct lightning strokes, the arresters are connected between the poles and all of the phase conductors in parallel with the insulators.

In this design, the total arrester stressing voltage is applied simultaneously to all of the three modules so that the voltage-time characteristics of the arresters are improved. The number of lightning outages n o caused by direct lightning strokes DLS on conductors of an unprotected line can be estimated by the following equation.

This voltage, however, is not as high as that for the lightning struck-conductor. The important feature of this modular long flashover arrester LFA-M is that it can be applied for lightning protection of overhead distribution line against both induced overvoltages and direct lightning strokes.

### Lightning Protection Using LFA-M | Seminar Report, PPT, PDF for ECE Students

For the protection of lines against direct lightning strokes, the arresters are connected between the poles and all of the phase conductors in parallel with the insulators. Therefore, this arrester should be relatively short. It is shown in lightnung figure 5. An LFA-M arrester consists of two cables like pieces. On the other hand, the potential of the adjacent phases also increases due to electromagnetic coupling between conductors but at much slower rate than that applied to the top phase insulator consequently, an outer phase arrester operates under much easier coordination conditions than a protectino phase arrester.

### LIGHTNING PROTECTION USING LFA-M

Registration Forgot your password? Where n 0 is 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 usijg n 0 for unprotected line to n 0 for lines protected by LFA arresters.

Therefore, in order to protect the line against the direct lightning stroke. This assures uninterrupted power supply of a LFA protected over head line. When the potential between the cloud and line exceed the breakdown value of air, the lightning discharge occurs between the cloud and the line.

If you wish to download it, please recommend it to your friends in any social system. When cloud discharges to earth, -ve charge rushes along both directions in form of travelling wave. A new simple, effective and inexpensive method for lightning protection of medium ligytning overhead distribution line is using long flashover arresters LFA.

In the case, it is essential to coordinate the arrestors and the insulators on the lightning struck phase A. The important feature of this modular long flashover arrester LFA-M is that it can be applied for lightning protection of overhead distribution line against both induced over voltage and direct lightning strokes.

Seminar Report on Plastic Roads. Lightnijg is a huge spark and that take place when clouds are charged to at a high potential with respect to earth object e.

## LIGHTENING PROTECTION USING LFA-M

Flashover of insulator Ins A indicates lightning protection failure. Charge on the cloud Q is bound by cloud R. Due to long flashover path, a flashover does not give rise to a power arc as the arc extinguishes when the power frequency current crosses zero. It can be applied for lightning protection of overhead distribution kightning against both induced over voltages and direct lightning strokes.

Feedback Privacy Policy Feedback. As a result probability of PAF for wooden structures is sufficiently lower than for steel or concrete supports. It is seen from Fig. Where N DLS is the number of direct lightning stroke DLS on a line; P I l is the probability of lightning current likely to cause flashovers of the line insulation; P arc is the probability of a power are caused by an impulse flashover an insulator; and P rc is the probability of successful line breakers enclosures.

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 rate of channel propagation on arrester modules is determined, and the. Static electricity is the accumulation of excess electric charges on an object.

The probability of PAF sharply decreases with a decrease in E. A new long flashover arrester model has been developed.

This is the reason why the calculation takes into account the critical values of the lightning current steepness I l l ,cr at which the insulator flashes over for a given set of parameters. It can be calculated from the formula.

The flashover performance of modular long-flashover arresters LFA-M arresters of two different flashover lengths and the voltage-time characteristics of LFA loop arresters, as well as those of the most common Russian insulators ShF G and ShF G with lengths 17 and 23 cm,respectively,were studied.

Topics For Seminar Back to the top. The induced over voltages can be counteracted by installing a single arrester on an overhead line support pole. Where n 0 is 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. You do not have the permission to view this presentation.

Posted by Sagar at 4: For the protection of lines against direct lightning strokes, the arresters are connected between the poles and all of the phase conductors in parallel with the insulators.

The rate of decrease of the critical gradient slows down for larger fault currents. Before flash over, the total resistance of the arrester can be assumed to be infinitely large. The induced over voltages can profection counteracted by installing a single arrester on an overhead protectio support pole. The calculation is carried out for a linear increase of the lightning current, that is.

A line with LFA arresters and INS insulators is shown to have a good lightning lighttning performance for direct lightning strokes. There are three clouds P,Q and R having positive, negative and positive charge respectively.

In order ksing view it, please contact the author of the presentation. Indirect stroke result from eletrostatically induced charges on the conductors due to the presence of charged cloud. The LFA’s length may be several times greater than that of an insulator string, etc.

Opposite charges attract, like repel Charged objects can cause electrons to rearrange their positions on a neutral object.