17 Dec Explore Lightning Protection Using LFA-M with Free Download of Seminar Report and PPT in PDF and DOC Format. Also Explore the Seminar. Presentation on theme: “LIGHTENING PROTECTION USING LFA-M”— System ”-A system of lightning protection conductors lightning rods -installed on the. 13 Jan The important feature of this modular long flashover arrester (LFA-M) is that it can be applied for lightning protection of overhead distribution.
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Lightning is an electrical discharge between cloud and earth, between clouds or between the charge centers of same cloud. This negative charge however will be jsing on that portion on the line right under the cloud and the portion of the line away from it will be positively charged.
It keeps increasing at a still slower rate until time t 3. Both results put an end to the calculation, and printout is produced.
Therefore, in order to protect the line against the direct lightning stroke. 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.
WordPress Embed Customize Embed. Efficiency can only be increased by number of flash over modules. Auth with social network: 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.
The cloud will induce a charge of opposite sign on the tall object.
LIGHTNING PROTECTION USING LFA-M
The induced positive charge leaks slowly to earth. Thus, the number of outages caused by direct prptection strokes can be lowered with the use of LFA arresters by an order of magnitude or more even for high values of grounding resistance.
It is designated as LFA-M. 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.
Therefore, this arrester should be relatively short.
The pole does not get involved in the path of the lightning current until the insulator or the arrestors have flashed over. In direct stroke, the lightning ligghtning is directly from the cloud to the an overhead line.
A line with LFA arresters and INS insulators is shown to have a good lightning protection performance for direct lightning strokes. As seen in fig 3. Unit 4 Ch A delta arrangement of conductors maximizes direct lightning strokes on the top center phase, which acts as shielding wire for the bottom outer phases.
The induced over voltages can be counteracted by installing a single arrester on an overhead line support pole. After the LFA A fully flashed over, the lightning current travels through the pole and its footing.
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. This has 3 main parts.
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. Posted by Sagar at 4: 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.
This assures uninterrupted power supply of a LFA protected over head line.
Seminar for you: Lighting protection using LFA-M
Fig 4 As illustration, let us consider the operation of phase A arrester. Can be applied for protection of distribution lines. Automatically changes to Flash or non-Flash embed.
A new long flashover arrester model has been developed. Charge on the cloud Q is bound by cloud R. It can be applied for lightning protection of overhead distribution line against both induced over voltages and direct lightning strokes.
The important feature of this lrotection long flashover arrester LFA-M is that oightning can be applied for lightning protection of overhead distribution line against both induced overvoltages and direct lightning strokes. An LFA-M arrester consists of two cables like pieces.
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. Each cable piece has a semi conductive core of resistance R The cable pieces are arranged so as to form three flashover modules 1,2,3. The arresters are connected between the pole and all of the phase conductors in parallel with the insulators.