Lightning arrester on broadcast television tower

Abstract

The invention relates to a lightning arrester on a broadcast television tower, which is used for smoothing lightning pulse current by using the characteristic that the current in an inductor cannot suddenly change, and further reducing the energy of the lightning pulse current by using eddy current loss generated by an iron core in an inductance coil. The lightning rod extends downwards, winds around the mast to form an inductance coil and then is connected with the mast, the mast is made of a soft iron material, and when lightning stroke pulse current passes through the inductance coil, the pulse current is smoothed, so that the pulse amplitude of the lightning current is reduced, eddy current loss is generated in the mast, the pulse amplitude of the lightning current is further reduced, and the lightning stroke is further reduced. And the damage of lightning stroke to radio and television equipment is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of lightning protection for radio and television, and particularly to a lightning protection device on a radio and television tower. Background Art

[0002] The traditional lightning protection method is to use a lightning rod to guide the electric field of the thundercloud. When the electric field breaks down the air and discharges, a lightning pulse current is formed and enters the ground through a metal conductor from the lightning rod. The peak value of the pulse current can be as high as 200 kA, generating a very large magnetic induction intensity and a high rate of change around the radio and television tower, and also generating a high voltage on the grounding resistance, which is likely to damage the radio and television transmitting equipment. Summary of the Invention

[0003] Aiming at the defects of the prior art, the present invention provides a lightning protection device on a radio and television tower, which uses the characteristic that the current in the inductor cannot change suddenly to smooth the lightning pulse current, and further reduces the energy of the lightning pulse current by the eddy current loss generated by the iron core in the inductor coil.

[0004] The technical solution adopted is that the lightning rod extends downward and is wound around the mast to form an inductor coil and then connected to the mast.

[0005] The mast is made of soft iron, and a support assembly is also installed at the top to support the lightning rod.

[0006] The inductor coil is in the shape of a cylindrical helix. An insulating sheath is also sleeved on the helix of the inductor coil. The insulating sheath extends upward to the lightning rod. Another rain-proof string is sleeved outside the upper part of the insulating sheath to prevent rain. The insulating sheath and the rain-proof string are used together to prevent the inductor coil, which generates self-induced voltage due to the lightning strike current, from discharging to the metal structure on the tower.

[0007] Further, the support assembly is used to fix the relative positions of the lightning rod and the mast, and includes: a cross arm, a clamp, and a grip sleeve; wherein, the cross arm is fixed at the top of the mast, the clamp cooperates with the cross arm to clamp the grip sleeve, and the grip sleeve is sleeved on the insulating sheath.

[0008] Furthermore, the rain-proof string is formed by stacking multiple umbrella-shaped rain-proof sections, which are sleeved on the insulating sheath and stacked on the grip sleeve. The umbrella-shaped rain-proof section is formed by an insulating hollow cylinder with an umbrella-shaped eaves. The through-hole diameter has an interference fit with the outer diameter of the insulating sheath to make it waterproof, and the umbrella-shaped eaves ensure that the column below it is not drenched. When it rains, no water flow forms on the surface of the insulating sheath with the rain-proof string sleeved on it, but instead drips from the outer edge of the umbrella-shaped rain-proof section. When a lightning current passes through the inductance coil to generate a self-induced voltage, it is used to prevent the upper exposed metal of the lightning rod from discharging to the metal structure on the tower through the water flow.

[0009] There is also a magnetic isolation section, made of non-magnetic steel material, with a flange, installed under the mast and then docked with the tower components below.

[0010] When lightning strikes, a pulsed current passes through the inductance coil. Since the current in the inductor cannot change suddenly, this pulsed current is smoothed, reducing the pulsed amplitude of the lightning current. At the same time, eddy current losses are generated in the mast, further reducing the pulsed amplitude of the lightning current.

[0011] When the mast is magnetized by the lightning current, the magnetic isolation section reduces the magnetic induction intensity of the tower components below to reduce the impact on the suspended antenna below.

[0012] This device has a small windward area and a simple structure, and can reduce the pulsed peak value of the lightning current, which is very beneficial for protecting radio and television equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The features of the present invention are described in detail in conjunction with the accompanying drawings. In the drawings, components with the same features and the same functions are only marked once, and bolts and nuts that are matched together are collectively called fasteners.

[0014] Figure 1 is a three-dimensional schematic diagram of a lightning protection device on a radio and television tower according to the present invention;

[0015] Figure 2 is a sectional view, exploded view, enlarged view, and rotated three-dimensional schematic diagram of the partial structure of a lightning protection device on a radio and television tower according to the present invention;

[0016] Reference numerals: 1 - mast, 11 - docking platform, 2 - lightning rod, 3 - inductance coil, 31 - docking plate, 32 - docking bolt, 4 - insulating sheath, 5 - rain-proof string, 51 - umbrella-shaped rain-proof section, 6 - grip sleeve, 7 - cross arm, 71 - cross arm fastener, 8 - clamp, 81 - clamp fastener, 9 - magnetic isolation section, 91 - flange fastener. DETAILED DESCRIPTION OF THE INVENTION

[0017] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The specific embodiments described are only illustrative of the present invention and do not limit the scope of the present invention.

[0018] A lightning protection device on a radio and television tower, the technical solution adopted is as Figure 1 and Figure 2 shown. The lightning rod 2 extends downward and winds around the mast 1 to form an inductance coil 3 and then is connected to the mast 1.

[0019] The mast 1 is made of soft iron, with a flange at the bottom and a support assembly at the top to support the lightning rod 2; in order to connect the inductance coil 3, a docking platform 11 is welded to the lower part of the mast 1. The surface of the docking platform 11 is formed with an excellent conductive plane by copper surfacing and has internal threaded holes.

[0020] The inductance coil 3 is in the shape of a cylindrical helix. The connection method of its lower end to the mast 1 is that a docking plate 31 is welded to the lower end of the inductance coil 3. The docking surface of the docking plate 31 is formed with an excellent conductive plane by copper surfacing and has bolt holes corresponding to the internal threaded holes of the docking platform 11. With the cooperation of docking bolts 32, the inductance coil 3 is fixedly docked on the mast 1; an insulating sheath 4 is also sleeved on the helix of the inductance coil 3, and the insulating sheath 4 extends upward to the lightning rod 2. A rainproof string 5 is further sleeved on the outer surface of the upper part of the insulating sheath 4 to prevent rain. The insulating sheath 4 and the rainproof string 5 together are used to prevent the inductance coil 3, which generates self-induced voltage due to lightning strike current, from discharging to the metal structure on the tower.

[0021] Furthermore, the support assembly, which is used to fix the relative positions of the lightning rod 2 and the mast 1, includes: a cross arm 7, a clamp 8, and a grip sleeve 6; among them, the cross arm 7 is fixed at the top of the mast 1 and is assembled with its supporting cross arm fastener 71; the clamp 8 cooperates with the cross arm 7 to clamp the grip sleeve 6 and is assembled with its supporting clamp fastener 81. The grip sleeve 6 is an insulating hollow cylinder with an annular groove in the middle. The through-hole diameter and the outer diameter of the insulating sheath 4 have an interference fit and are sleeved on the insulating sheath 4; the cross arm 7 and the clamp 8 also each have a notch that matches the annular groove of the grip sleeve 6 and are installed in cooperation with each other.

[0022] Furthermore, the rain-proof string 5 is formed by stacking multiple umbrella-shaped rain-proof joints 51. It is sleeved on the insulating sheath 4 and stacked on the grip sleeve 6. The umbrella-shaped rain-proof joint 51 is formed by an insulating hollow cylinder with an umbrella-shaped eaves. The through-hole diameter and the outer diameter of the insulating sheath 4 have an interference fit to make it waterproof. The umbrella-shaped eaves ensure that the column below it is not drenched. When it rains, no water flow forms on the surface of the insulating sheath 4 sleeved with the rain-proof string 5, but drips at the outer edge of the umbrella-shaped rain-proof joint 51. When a lightning current passes through the inductance coil 3 to generate a self-induced voltage, it is used to prevent the upper exposed metal of the lightning rod 2 from discharging to the metal structure on the tower through water flow.

[0023] There is also a magnetic isolation joint 9, made of non-magnetic steel material, with a flange, installed under the mast 1, assembled with its matching flange fastener 91, and then docked with the lower tower components.

[0024] When lightning strikes, a pulsed current passes through the inductance coil 3. Since the current in the inductor cannot change suddenly, this pulsed current is smoothed, reducing the pulsed amplitude of the lightning current. At the same time, eddy current losses are generated in the mast 1, further reducing the pulsed amplitude of the lightning current.

[0025] When the mast 1 is magnetized by the lightning current, the magnetic isolation joint 9 reduces the magnetic induction intensity of the lower tower components to reduce the impact on the suspended antenna below.

[0026] In specific implementation, the inductance of the inductance coil 3 of the present invention, the insulation strength of the insulating sheath 4 and the rain-proof string 5, and the length extending into the lightning rod 2 are all limited by the rate of change of the lightning current and the insulation strength of the air during lightning strikes.

[0027] The larger the inductance of the inductance coil 3, the better the effect of smoothing the pulsed lightning current, the higher the generated self-induced voltage, and the higher the required insulation strength of the insulating sheath 4 and the rain-proof string 5.

[0028] According to the national standard GB 50057-2010 Code for Design of Lightning Protection of Buildings, the air breakdown strength value under lightning strike environment is 500 kV / m, and the steepness value of the lightning current is 200 kA / μs.

[0029] Furthermore, a preferred solution is the design of the key part: the insulating sheath 4 extends onto the lightning rod 2, and the extended length is more than 2 m upward beyond the grip sleeve 6. The length of the rain-proof string 5 above the grip sleeve 6 is also 2 m. The rest of the upper part of the lightning rod 2 is exposed. The insulating sheath 4 and the rain-proof string 5 are made of polytetrafluoroethylene material with an insulation strength above 50 kV / mm. The wall thickness of the insulating sheath 4 is 20 mm, and the wall thickness of the hollow cylinder of the umbrella-shaped rain-proof section 51 in the rain-proof string 5 is 10 mm. In this configuration, the self-induced voltage generated when the lightning current flows through the inductor coil 3 needs to exceed 1000 kV to cause the lightning rod 2 and the inductor coil 3 to discharge to the metal structure on the tower.

[0030] Furthermore, a preferred solution is the design of the key part: the inductance of the inductor coil 3 is 4 μH. In this configuration, when there is a lightning current, since the current in the inductor cannot change suddenly, the lightning current flowing through the inductor coil 3 will be smoothed, and its steepness will also be lower than 200 kA / μs. The self-induced voltage generated on the inductor coil 3 will also be lower than 800 kV, and even lower than the above 1000 kV voltage.

[0031] According to the above design, the self-induced voltage generated on the inductor coil 3 during lightning will not cause discharge, and the lightning current will smoothly pass through the inductor coil 3, completing the function of reducing the peak value of the lightning current pulse of this device.

[0032] The specific implementation manners and the technical contents and features of the examples of the present invention have been disclosed above. Under the creative concept of the present invention, those skilled in the art can modify the technical solutions recorded in the above embodiments, or perform equivalent replacements for some of the technical features. All such modifications and replacements shall fall within the protection scope of the appended claims of the present invention.

[0033] The descriptions of the above embodiments and examples are exemplary rather than restrictive.

Claims

1. A lightning protection device on a radio and television tower, characterized in that: The lightning rod extends downward and is wound around the mast to form an inductance coil and then connected to the mast. The mast is made of soft iron and is provided with a support assembly at the top to support the lightning rod. The inductance coil is in the shape of a cylindrical spiral line. The spiral line of the inductance coil is also covered with an insulating sheath, which extends upward to the lightning rod. The upper part of the insulating sheath is also covered with a rainproof string.

2. The lightning protection device on a radio and television tower according to claim 1, characterized in that: The support assembly includes: a cross arm, a clamp, and a gripping sleeve; wherein the cross arm is fixed to the top of the mast, and the clamp cooperates with the cross arm to clamp the gripping sleeve, and the gripping sleeve is sleeved on the insulating sheath.

3. The lightning protection device on a radio and television tower according to claim 1, characterized in that: The rainproof string is composed of multiple umbrella-shaped rainproof nodes stacked together, which are put on the insulating sheath and stacked on the grip sleeve. The umbrella-shaped rainproof node is formed by an insulating hollow cylinder with an umbrella-shaped eaves, and the through-hole diameter thereof is interference fit with the outer diameter of the insulating sheath.

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