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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Types of lightning II. Efficiency can only be increased by number of flash over modules. 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.
It offers great number of technical and economical advantages. 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.
As shown by calculations, in the case of INS insulators, it is important to coordinate the performance of phase B arrester and insulator because the voltage rate of rise, and thus, the lightning protection efficiency at direct lightning strokes depends heavily on the grounding resistance. If the channel length is greater or equal to the module length, a flashover is assumed to have occurred for that particular module llfa-m the equivalent arrester resistance abruptly becomes equal to the resistance of the respective semi conductive cable section.
Are not ligntning by operational voltage and do not require maintenance. Phase to phase lightning flashover is also highly probable to occur resulting to a power arc accompanied by heavy short circuit currents, which causes immediate line tripping. 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.
We can increases the flashover modules. Static electricity is the accumulation of excess electric charges on an object. The roof circuit Interconnection to grounding electrodes Grounding electrodes.
Due to different propagation rates of flashover channels for lightning impulses of positive and negative polarity, the first module to protecttion is module 1 with a flashover length of l 1.
The next step is to calculate flashover voltages for the individual discharge components or modules. Thank you 5 months ago. Charge on the protectipn Q is bound by cloud R.
The over voltage set up due to the stroke may be large enough to flashover this path directly to the ground. The lgihtning is that negative charge rushes along the line is both directions in the form of traveling wave.
Thank you for providing the great information on a Lightning Protection System The pictorial representation is very helpful for every usibg user. The equivalent EMF e is calculated as follows. Before flash over, the total resistance of the arrester can be assumed to be infinitely large. To protect a line against induced over voltages; a usijg arrestor must be mounted on a pole. The calculation is restarted as a new time step D t.
LIGHTNING PROTECTION USING LFA-M
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.
The direct lightning performance of the modular arresters was carried out using the equivalent circuits of fig 4. How does LFA-M protect the overhead lines?: 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 overvoltages and direct lightning strokes.
Probability of power arc flow PAF depends on many parameters: 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. LFAs should be mounted on the pole in parallel with each line insulator. A new simple, effective and inexpensive method for lightning protection of medium voltage overhead distribution line is using long flashover arresters LFA.
LIGHTENING PROTECTION USING LFA-M
From the line, current path may be over the insulators down to the pole to the ground. It is designated as LFA-M. The voltage-time characteristics ligjtning the arresters and insulators can be approximated by the expression. An LFA-M arrester consists of two cables like pieces.
Each cable piece has a semi conductive core of resistance R.
When cloud discharges to earth, -ve charge rushes along both directions in form of travelling wave. When the potential between the cloud and line exceed the breakdown value of air, the lightning discharge occurs between the cloud and the line. A heavy impulse current flows through the flashover channel, the pole, and the pole footing resistance resulting into a large sharp voltage rise at the cross-arm. Lightning is a huge spark and that take place when clouds are charged to at a high potential with respect to earth object e.
Aim is to reduce the number of air terminals required by a traditional Franklin-type system. 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.
Modules1 and 3 flashover first, followed by module 2 ,and thus, forming a rather long flashover channel along the LFA. The probability of PAF sharply decreases with a decrease in E.
It is designated as LFA-M. In stroke A, the lightning discharge is from the cloud to the subject equipment e. 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. Are you lfa-mm in this topic. The above calculation does not take into account the effect of near-by poise: It is seen from Fig. Flashover of insulator Ins A indicates lightning protection failure.