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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LIGHTNING PROTECTION USING LFA-M
Pole-top arresters were used to protect distribution line from induced voltage flashovers. It offers a great protectiom of technical and economic advantages.
Protection against Lightning Overvoltages Overvoltages due to lightning strokes can be avoided or minimized in practice lfa-j d shielding the overhead lines. A new long flashover arrester model has been developed. Newer Post Older Post Home. Tests have been shown that, as the line conductor is stressed by lightning over voltage impulse, flash over channel develop at different rates.
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It was assumed to be equal to zero. From the short analysis presented above, it is clear that it is possible to improve the protection lightnijg lightning by increasing the length of lightning flashover path. The over voltage set up due to the stroke may be large enough to flashover this path directly to the ground. This assures uninterrupted power supply of a LFA protected over head line.
LIGHTNING PROTECTION USING LFA-M
Lightning is an electrical discharge between cloud and earth, between clouds or between the charge centers of same cloud. Some results of published lighting studies on the critical gradient are shown in fig3.
The ilghtning of the power frequency voltage of a kV line on discharge process on the arrester surface is negligible. Are you interested in this topic. The suggested LFA accomplishes this principle. Thus, the insulators of the healthy phases are stressed and flashed over by a voltage equal to the potential difference between the cross arm and the phase conductor.
Seminar Report on Plastic Roads. The cable pieces are arranged so as to form three usung modules 1,2,3 as shown in figure1. Therefore the total voltage U is applied to each flashover module at the same moment, and all three modules are assured conditions for simultaneous ysing of creeping discharges developing in to a single long flashover channel. The rate of decrease of the critical gradient slows down for larger fault currents.
As tests have shown, module 3 of phase a arrester will usually flash over after module 1.
Long Flashover Arrester (LFA) Seminar Report
Advertise on this site?? The over voltage set up due to the stroke may be large enough to flashover this path directly to the ground. In stroke A, the lightning discharge is from the cloud to the subject equipment e. Don’t enter email or mobile no.
LIGHTENING PROTECTION USING LFA-M – ppt video online download
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 uing long flashover channel PowerPoint Presentation: When the potential between the cloud and line exceed the breakdown value of air, the lightning discharge occurs between the cloud and the line.
It follows from the previously described sequence of events that direct lightning stroke causes flashover of all the insulators on the affected pole. Finally, the calculation is checked for completion.
The induced over voltages can be counteracted by installing a single arrester on an overhead line support pole. The voltage-time characteristics of this modular arrestor assure reliable protection of medium voltage overhead lines against both induced over voltages and direct lightning strokes.
It should also be remembered that even large lightning currents do not present any hazards to these arrestors because the discharge develops in the air and not inside the device. The induced overvoltages can be counteracted by installing a single arrester on an overhead line support pole.
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 direct stroke can be of two types 1. The shielding failure of the outer phases is reduced and it is given by the following equation.