REDUCER OF LENS EFFECT AND SURFACE ELECTRIC GRADIENT IN

LIGHTNING RODS

The present invention refers to a large size device capable of intercepting and conducting direct atmospheric discharges of electricity, also called lightning, to ground. The device has great importance in safety issues when used to replace the conventional down conductor in lightning rods. The device is capable of reducing the Lens effect and surface electric gradient produced by a lightning discharge and can be applied with the conventional lightning attractor invented by Benjamin Franklin or others. In 1752, Benjamin Franklin, after his Hypothesis, innovative at that time, that clouds could be loaded with electricity, considered lightening and thunders as electric phenomena. Starting from this principle, Benjamin Franklin developed the lightning rod, after concluding that lightning is in fact an electric flow and this form of energy could not be of great use for the humanity in the future.

The first devices were built with a rod inserted into the ground that intercepted and conducted the charge to the ground, such as a tree, in which the top intercepted the atmospheric discharges and the trunk conducted them to the roots that dissipated them to ground. With the appearance of electronics at the beginning of the last century, the needed improvements were made to adapt new electronic devices to these pieces of equipment, which are placed on metal towers and large concrete edifices or in other proximities.

An example of these improvements is the receptor, isolated and with several points, and also the down conductor, which goes down isolated from the tower or brick wall and is connected to the ground system following the Kirchhoff s circuit laws. That is, it is a circuit with sources, resistors (wires) and other circuit elements that form a mesh where the algebraic sum of the electrical potencial differences around any closed circuit must be zero. These technologies with no significant changes since their invention are still universally used in most constructions. However, when dealing with large meteorological electric loads of short duration, the conventional down conductor

has always the inconveniences caused by the Lens effect and its consequent electromagnetic induction in electric and electronic circuits applied to telecommunication towers, such as buildings and other constructions, when lightnings are intercepted by conventional elements. These disturbances occur because a current induced in a certain direction or sense due to a change in the magnetic field exerted on the mobile wire tends to oppose the flux, or to exert a mechanical force to oppose the motion. This current produces effects that tend to oppose to the variation in the system status because of the difference in potential and work done per unit charge.

This physical characteristic is one of the greatest problems of lightning rods, because of the work done per unit charge, since these inductions are functions of the inverse square of the distance between the conventional down conductor and the parallel electric conductors in the vertical sense. No technology containing the specificities of the invention here described was found in searches carried out in patent databases.

The present invention was researched and developed to reduce the Lens effect (electromagnetic induction) and the surface electric gradient, from the moment that an atmospheric discharge reaches the lightning rod. It consists of an armored passageway capable of conducting safely a direct lightning within a large-size cylindrical capacitor, without the electromagnetic inductions, which are blocked by the armored passageway, cause severe damages to several pieces of equipment. As examples, we can mention analog and digital electric meters; contactors during switching-off operation, where pulses melt the contact elements forming bubbles that hinder the closing operation and cause heating and destruction and the consequent stopping of a productive sector that uses large potencies; electrical equipment of large capacitances such as engines and other grounded equipment; as well as heavily grounded electronic equipment like PABX, parabolic antennas, telecommunication systems, data processing, among others.

The cylindrical capacitor, part of the present invention, is termed coaxial cable and its operation follows the mathematical principals of Pointing, Maxwell

and Kelvin; an electric flow formed by the pellicular effect of a lightning, as described previously, is trapped inside the tube, according to Lorens' concepts, and consists of a coaxially-shaped central conductor where the magnetic field formed by the progress of the electric charge keeps the flow close to this central conductor, without reaching the external metal coating. This way, the short- duration flow can be conducted to the ground with maximum safety and minimum electromagnetic induction, reducing therefore the Lens effect, which is the self-induction of an electric flow in opposition to the applied pulse and that could be intercepted by the electric system, causing damages in electric and electronic equipment as well as interfering with computer systems.

This Lens effect and surface electric gradient reducer means consists of, as Figure 1 shows and clarifies, a large-size coaxial cable (A), having in its center a large gauge conductor (B), which has the external mesh of the coaxial cable (A) properly dimensioned and made for this purpose, i.e., the cable should be chosen to support bad weather and its consequences.

The coaxial cable can be formed in a round shape, if necessary depending on the place to be installed, with the curvature not exceeding 10 degrees. One should not ignore that water or humidity entering into the cable or coaxial cable will compromise the operation efficiency of the present invention, which has to be exposed to bad weather and prepared to cope with it. The preferable material for its production is porcelain for insulating pieces, and stainless material for metal parts. Alternatively, other materials with similar physical characteristics to the above mentioned may be used, such as ceramic.

The external mesh of this coaxial cable is connected to the metal box (E) through the connection (C) and has a conductor at the bottom (B) and at the same time a connector (G) for direct connection to the main ground element that should be unitary, long and encased. This connector (G) is isolated from the metal box (E) and through a bushing well that is part of the supporting body (D) manufactured in porcelain or other materials. The central conductor (B) of the present invention consists of a large- gauge cable or wire, rigid or flexible, or other conductive materials, formed by a single or several wires, but not twisted or braided as the traditional down cables

and should have sufficient gauge to handle electric discharges and properly isolated using porcelain rings or other insulating materials, non-restricted and durable (M) ₁ which should be separated from bottom to top, where there is a metal anti-corona ring (J) designed to prevent the Corona effect. Thus, the metal ring is covered by an insulating piece (K) of porcelain or other insulating materials resistant to bad weather and having as main function to avoid that partial atmospheric discharges reach the external part of the coaxial mesh (A).

This central conductor (B) has the top part connected by threads or bayonet-type, connection, to a conventional element of lightning interception or others. The bottom end of the central conductor (B) is connected to the top part of a large-size arrester (I) also inserted in a large-size porcelain body (D) or other materials resistant to fatigue by time, with an opening (H) and a large-size inductor (F) welded to the elements of the arrester (I). This inductor has the function of conducting the static electricity from the soil to the lightning- intercepting element, not interfering with the passage of the atmospheric electric current flow.

Connection to ground has special details that should be considered, because of the pellicular effect (Kelvin) caused by a lightning. Therefore, the connector element (G) is isolated from the metal box (E) through an insulated bushing well. This insulated bushing well is integral part of the supporting body (D) and is directly linked to the element of unified ground, and the connectors (G.1 and G.2) are unilaterally welded or connected to the right and left side of the metal box (E). These connectors have independent cables to connect with the superficial ground or with the unitary element of encased ground with pattern connection in a Kirchoffs mesh. The closing knot, where cables join the unitary ground element, is quite long and has one fourth of its length encased with pvc or other material that in a critical situation will be able to collect water to keep some moisture in this referred ground.

Figure (1 ) indicates how the present device replaces the traditional down cable of lightning rods, as well as its installation.

Figure (2) illustrates this ground model whose main characteristic is to have a very short time of response, bellow or equal to one microsecond, since

the coaxial mesh and the soil work together as a coaxial cable, dissipating, therefore, the high-intensity electric current flow in the underground with consequent reduction in surface electric gradient.

The apparatus, object of the present invention, a large size industrial product, is to equip lightning rods and protect electronic equipment and living beings against the dangerous Lens effect and soil electric potential, also known as step voltage, with deadly action on quadruped animals.

The apparatus, here described, is capable of conducting safely a lightning from the reception element to the ground, where it will meet a special ground system capable of dissipating large electric loads of high energetic magnitudes and short duration.

Figure (2) shows the unified and encased ground system formed by a galvanized (or other material) long pipe (A) where three fourths of its length is grounded (B) and one fourth of the same is encased (C) and skirts the ground (B). The Lens effect reducer means is directly connected to the pipe (A), through the main ground connector (G) as in Figure (1).

As the present invention cannot be directly connected to the conventional surface ground, it uses the secondary ground connectors G.1 and G.2 to do this function, which should have low ohmic value. Figure 3 shows the applications of the apparatus, and Figures (4) and (5) demonstrate an application in a metal structure, as a tower, for example.

When the intercepted electric load is conducted to the coaxial cable (A) indicated in Figure (1) it starts settling down on the surface of the internal conductor (B) and as the time elapses, it is gradually distributed from the conductor's surface (B) to its center, until this distribution becomes uniform within the central conductor (B) and then it flows regularly towards the arrester (I) and the main ground through the connector (G) which is linked to the pipe (A) as in Figure 2.

The present invention, follows the principles of optimal impedance, characteristic of the most perfect line possible, as when the pulse arrives at the starting point of the conductor (B) ₁ it meets resistance, but as soon as the pulse spreads over the line, the resistance becomes insignificant until it gets to the

arrester (I), then the pulse passes freely to the main ground connector (G) completely ignoring the inductor (F) and moves on to the ground conductor that has an exit passage through which the pellicular electric flow will dissipate into the ground, producing a minimum of surface electric gradient (step voltage). This is a high interest technology to intensive cattle raising, in which large herds are concentrated on small areas during storms and making the step voltage the largest cause of death in these areas.

Considering that the difference in potential between animals' paws and soil surface can cause a heart attack and consequent death, bringing losses for farmers and other technical and economic situations, the present invention presents a solution for the state of the technique.

Another very important application of the present invention is to prevent fires caused by lightnings in large-size forests, because of the characteristic of conducting internally a discharge and dissipating it into the ground, the likelihood of a lightning to cross the apparatus and cause a forest fire is almost null.

In this situation, or in a similar one, the apparatus object of the present invention is central part of the metal structure of a support tower, where the central support pipe of the tower is at the same time the large-size coaxial cable (A). In this way, it is possible to integrate the apparatus to the metal support tower in an economical way, forming only one product composed by apparatus and metal tower with wide use in the city and in the field.

This metal tower holds a series of cables forming a professional system of electric cabling, to be used and standardized, if possible, for application to drawing electricity from the concessionary company, in the case concession, to the electricity meter and/or electric protection, with the main object of standardizing and optimizing the characteristic impedance of the electric entrance cable.

This professional system of electric cabling allows means to facilitate atmospheric electromagnetic pulse to pass through the protection device against overload (disjunctor) and soon after, the protection device against electrometeorological disturbances, and also it lets RF signs pass and prevent

the possibility of tampering or anyone from stealing electricity before reaching the electricity meter. This is possible because rupture is almost impossible when the cable is energized and connected to the commercial electric grid of the electricity concessionary company through a sealed connector and installed by the concessionary.

This series of power cables or universal service operates inversely to the one used at the exit of the electricity meter and/or electric protection. The objective is to transport electrical energy with a minimum ohmic loss and RF signs for data transmission, break of the perfect characteristic impedance by the application of the twisted double cable, hindering the passage of induced electromagnetic pulses, from character or atmospheric causes, with some transient characteristics.

Field research with real-world phenomena has demonstrated that this type of cable does not allow them to move easily, hindering their arriving at the tripolar power plug, which has, optionally, a disjunctor or external fuse.