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 induced over voltages can be counteracted by installing a single arrester on an overhead line support pole. For direct lightening -arrestors are connected between poles and all the phase conductors in parallel with the insulators.
As indicated before, the coordination of arrester LFA A is not depend on the grounding resistance because The pole does not get involved in the path of the lightning current until the insulator or the arrestors have flashed over. Thus the total voltage is applied to each flashover module at the same moment, and all the three flashover modules 1, 2 and laf-m are assured conditions for simultaneous initiation of creeping discharges which,with respective modules flashed over, develop a single long flashover channel.
The over voltage setup due to the stroke may be large enough to flashover this path directly to the ground.
Long Flashover Arrester (LFA) Seminar Report
Types of lightning II. To make this website work, we log user data and share it with processors. Flashover of insulator Ins A indicates lightning protection failure. 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.
Where N DLS is the number of direct lightning stroke DLS on a line; P I l is the usiing of lightning current likely to cause flashovers of the line lightjing 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.
Charge on the cloud Q is bound by cloud R. Registration Forgot your password? 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. Published by Sherman Lindsey Modified over 2 years ago. It proection designated as LFA-M. When the potential between the cloud and line exceed the breakdown value of air, the lightning discharge occurs between the cloud and the line.
LIGHTENING PROTECTION USING LFA-M – ppt video online download
The cable pieces are arranged so as to form three flashover modules 1,2,3 ,fa-m shown in figure1. Advertise on this site?? Both results put an.
It is designated as LFA-M.
LIGHTNING PROTECTION USING LFA-M
Static electricity is the accumulation of excess electric charges on an object. Then it can withstand very high over voltages. When the potential between the cloud and line exceed the breakdown value of air, the lightning discharge occurs between the cloud and the line. The voltage rate lightnin rise U l is proportional to steepness of the protedtion current. Opposite charges attract, like repel Charged objects can cause electrons to rearrange their positions on a neutral object.
Aim is to reduce the number of air terminals required by a traditional Franklin-type system. A delta arrangement of conductors maximizes direct lightning strokes on the top center phase, which acts as shielding wire for the bottom outer phases. Unit 4 Ch The shielding failure of the outer phases is reduced and it is given by the following equation. Are not stressed by operational voltage and do not require maintenance. An LFA-M arrester consists of two cables like pieces.
From the line, current path may ligtning over at the ground.
You do not have the permission to view this presentation. Lightning is a huge spark and that take place when clouds are charged to at a high potential with respect to protecttion object e.
From the short analysis presented above, it is clear that it is possible to improve the protection against lightning by increasing the length of lightning flashover path. Equation A4 of the Appendix is used to find the rate of propagation of discharge channels in modules 1 and 3 of arrester LFA A and the distance covered by these channels over time D t. Share buttons are a little bit lower. With the INS insulators the number of lightning outages is lowered by a factor of five, the outage reduction factor K DLS being practically independent of the grounding resistance.
This assures uninterrupted power supply of a LFA protected over head line.
Newer Post Older Post. Electricity Foundations of Physics.
To protect a line against induced over voltages; a single arrestor must be mounted on a pole. For example world, us etc III. The induced over voltages can be counteracted by installing a single arrester on an overhead line support pole.
If a flashover occurred on at least one of the insulators Ins A or Ins B. Extend the ligntning life of high voltage circuit breakers. The cloud will induce a charge of opposite sign on the tall object. How does LFA-M protect the overhead lines?: The average span length I span of a kV line is usually about 70m.
Where k is the outage reduction factor of lightning outages caused by direct lightning strokes. Edirisinghe T Department of EE. It offers great number of technical and economical advantages. A line with LFA arresters and INS insulators is shown to have a good lightning protection performance for direct lightning strokes. If the channel length is greater or equal to the module length, a flashover is assumed to have occurred for that particular module and the equivalent arrester resistance abruptly becomes equal to the resistance of the respective semi conductive cable section.
Vitthal Patnecha 13 January How lightning is formed.