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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The voltage rate of rise U l is proportional to steepness of the lightning current. Opposite charges attract, like repel Charged objects can cause electrons to rearrange their positions on a neutral object. Vitthal Patnecha 13 January 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 initiation of creeping discharges which,with respective modules flashed over, develop a single long flashover channel PowerPoint Presentation: A new long flashover arrester model has been usng.
Since phases B and C and their arresters operate under identical conditions, it is practical to combine them in an overvoltage analysis. The LFA principle, its main applications and some laboratory test results are presented. 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 lihgtningcr.
Long Flashover Arrester (LFA) Seminar Report
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.
Phase-to-phase faults on a pole can give rise to fault current in order of a few kiloampers. The induced overvoltages can be counteracted by installing a single arrester on an overhead line support pole.
Thank you 5 months ago. Thus, the voltage on the cross arm increases at a much slower rate than it does on the lightning struck conductor before the flashover of usnig top usihg LFA.
Protection against Lightning Overvoltages Overvoltages due to lightning strokes can be avoided or minimized in practice by d shielding the overhead lines.
Auth with social network: In stroke A, the lightning discharge is from the cloud to the uisng equipment e. The roof circuit Interconnection to grounding electrodes Grounding electrodes.
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. Systems that provide an increased zone of protection Systems that eliminate lightning strikes altogether. Types of lightning II. The cable pieces are arranged so as to form three flashover modules 1,2,3 as shown in figure1. Posted by Sagar at 4: From the line, current path may be over the insulators down to the pole to the ground.
At this point, the calculation is stopped and the output is printed, including the steepness of the lightning current I 1 1 at which the insulator flashed over. The equivalent EMF e is calculated as follows. If the number liyhtning flashover modules increases by increasing the cable pieces this LFA-M can be used for lightning protection of very high voltage lines.
Due protectoon different propagation rates of flashover channels for lightning impulses of positive and negative polarity, the first module to flashover is module 1 with a flashover. Its resistors assure application of the total arrestor-stressing voltage simultaneously to all the modules. 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 Pfotection and ShF G with lengths 17 and 23 cm,respectively,were studied.
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. It is stressed by fairly steep over voltage impulses associated with direct lightning strokes on a conductor.
Similarly, the semiconducting core of the lower piece of the same resistance applies the low potential 0 to the surface of the upper piece, also at its center.
An LFA mounted on the top phase must flash over before the top phase insulator. From the line, current path may be over the insulators down to the pole to the ground. A delta arrangement of conductors maximizes direct lightning strokes on the top center phase, which acts as shielding wire for the bottom outer phases.
Therefore the total voltage U is applied to each flashover module at the same moment, and all three modules are assured conditions for simultaneous initiation of creeping liyhtning developing in to a single long flashover channel.
It offers great number of technical and economical advantages. When the cloud discharges to earth or to another cloud, negative charge on the wire is isolated as it can not flow quickly to earth over the insulator. The over voltage set up due to the stroke may be large enough to flashover this path directly to the ground. Both results put an end hsing the calculation, and printout is produced. It is designated as LFA-M.
There are three clouds P,Q and R having positive, negative and positive charge respectively. Electricity The movement of charge from one place to another Requires energy to move the charge Also requires conductors. The rate of channel propagation on arrester modules is determined, and the modules are checked for flashovers. In direct stroke, the lightning discharge is directly from the cloud to the an overhead line.
LIGHTENING PROTECTION USING LFA-M
With one or both outer phase arresters activated, a two or three phase lightning flashover is initiated. Lightning is an electrical discharge between cloud and earth, between clouds or between the charge centers of same cloud.
The important ysing of this modular long usig arrester LFA-M is that it can be applied for lightning protection of overhead distribution line against both induced overvoltages and direct lightning strokes. The flashover length, L is greater for lines with wooden structures rather than steel or concrete structures, because wooden Cross-arm increases the flashover path.
It was recommended to install an arrester at every insulator. Blockchain Technology Seminar Report. Probability of power arc flow PAF lightnung on many parameters: Some results of published experimental studies on the critical gradient are shown in fig3. Lightning is an electrical discharge between cloud and the earth, between clouds or between the charge centers of the same cloud.