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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For example world, us etc III. Before flash over, the total resistance of the arrester can be assumed to be infinitely large. From the line, current path may be over the insulators down to the pole to the ground.
Time is usinv in equal steps D t. It offers great number of technical and economical advantages. The induced positive charge leaks slowly to earth.
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 usinh 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. The equivalent EMF e is calculated as follows. 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.
Posted by Sagar at 4: A delta arrangement of conductors maximizes direct lightning strokes on the top center phase, which acts as shielding wire for jsing bottom outer phases.
Majority of the surges in a transmission lines are caused by indirect lightning stroke. In this design, the total arrester stressing voltage is applied simultaneously to all of the three modules so that the voltage-time protction of protectiob arresters are improved. The arresters are connected between the pole and all of the phase conductors in parallel with the insulators.
If the number of flashover modules increases by increasing the cable pieces this LFA-M can be used for lightning protection of very high voltage lines. It was assumed to be equal to zero. It is stressed by fairly steep over voltage impulses associated proyection direct lightning strokes on a conductor.
Therefore, in order to protect the line against the direct lightning stroke. Next, the insulators and arresters voltage-time characteristics VTCs are entered in an analytical form.
Share buttons are a little bit lower. For a lightning stoke on a phase conductor, the lighting current propagates both ways from the stroke point overcoming the surge impedance Z s of the line. Electricity The movement of charge from one place to another Requires energy to move the charge Also requires conductors. 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. Early streamer emission Radioactive rod systems Laser induced systems Charge transfer systems.
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.
Before flash over, the total resistance of the arrester can be assumed to.
LIGHTNING PROTECTION USING LFA-M
The result is that charge on cloud R suddenly become free and it then discharges rapidly to earth, ignoring tall object. A line with LFA arresters and INS insulators is shown to have a good lightning protection performance for direct lightning strokes.
Labels Seminar Topics 3 Welcome 1. Edirisinghe T Department of EE. In stroke B the lightning discharge occurs on the overhead line as ligthning result of stroke A between the clouds. Provides a low-impedance path for the lightning current to lessen the heating effect.
The voltage-time characteristics of the arresters and insulators can be approximated by the expression. Fig 4 As illustration, let us consider the operation of phase A arrester.
The cloud will induce a charge of opposite sign on the tall object.
Flashover of insulator Ins A indicates lightning protection failure. It offers great number of technical and economical advantages.
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 can be clearly seen that as the grounding resistance increases, the critical lightning current steepness I l l ,cr decreases. Thank you 5 months ago. Therefore, this arrester should be relatively short.
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. Efficiency can only be increased by number of flash over modules. Thus, t tr is larger than t cr. Automatically changes to Fla-m or non-Flash embed.
The average span length I span of a kV line is usually about 70m. The over voltage set up due to the stroke may be large enough to flashover this path directly to the ground. If only a partial flashover of the arrester lighhtning.
LIGHTENING PROTECTION USING LFA-M – ppt video online download
Types of Lightening Strokes 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. To protect a line against induced over voltages; a single arrestor must be mounted on a 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.
Lighting is formed by: