Lightning arrester and lightning protection deviceTechnical Field
The invention belongs to the technical field of lightning prevention and control, and particularly discloses a lightning arrester and a lightning protection device using the same.
Background
Lightning is a rapid discharge process between one part of charged cloud layer and another part of cloud layer with heterogeneous charges or between the charged cloud layer and the ground. The discharge between the cloud layers is harmful to the aircrafts, and the discharge of the cloud layers to the ground is harmful to the buildings, the electronic and electrical equipment, people and livestock.
Modern meteorology gradually improves the recognition of thunder and lightning, and people recognize that when the field electricity between thundercloud and the ground is enhanced to a certain degree, and the gap distance is long, when the current flows are insufficient to penetrate through two poles, a plurality of current flows are gathered together, so that the ionization of an original discharge channel is enhanced, the ionization channel is prolonged, and a form of gas discharge channel development gradually develops towards a discharge electrode is realized. The lightning rod is called as pilot discharge, based on the pilot discharge technology, technicians develop the lightning rod, so that charges accumulated in a cloud layer are led into the ground preferentially due to lightning rod tip lightning, and therefore the lightning stroke of a building, electronic and electric equipment or people and livestock is avoided.
In the last twenty years, people find new knowledge of lightning ascending leader, the survival, development, maintenance and existence time of the leader are only in millisecond level, the whole process is difficult to observe visually, and the leader process is easy to submerge in subsequent discharge. With the progress of technology, the coexistence of a plurality of downstream pilot discharges and a plurality of upstream pilot discharges is found out in the actual site and the laboratory by using a high-speed imaging technology
Lightning discharges are accomplished in the atmosphere. Modern physics suggests that there must be recombination of two polarity charges in the presence of light from an electrical discharge in a gas.
Positively charged molecules absorb electrons (or rob electrons in negatively charged molecules) and the energy level of the molecules will drop and the release of this energy will occur in the form of photons of a certain wavelength. If only charges of a single polarity are moved in air, no light will be seen. So that there must be a charge of both polarities in motion that recombines in air as long as light is seen. Intense luminescence must exist in a number of charge transient recombination processes.
The gas-penetrating discharge emits light, and the striking discharge emitted from the opposite electrode is indispensable in addition to the discharge electrode. As small as fluorescent lamps and neon lamps, as large as laboratory discharge and lightning discharge in the atmosphere. The cathode-ray tube is a tube in which electron beams of a single polarity move in vacuum, so that no light is emitted from the inside, and only after the electron beams reach the anode fluorescent layer, the electron beams are captured by fluorescent materials, so that fluorescence on the fluorescent screen is generated. Each of the thundercloud down lead and the ground up lead has one charge, but can see its luminescence, which illustrates that there is still some amount of recombination process. The other polarity charge required in the recombination process is mainly derived from the ionization process of air by the high field strength at the end of the discharge leader.
The high field strength can ionize the main air molecules. After the molecules are ionized, the molecules with the same polarity are left in place and used as the extension of the guide, and the opposite polarity charge molecules (particles) move to the guide discharge generation point along the guide channel under the action of the electric field in the channel, and continuously generate a recombination process to generate luminescence. The brightness of the pilot is not too high due to the limited number of ionisations and the recombination process continues until the point where the pilot discharge occurs.
Luminescence is an energy output process. In the previous development process, the energy stored in the thundercloud electric field is converted into light energy to be output. The energy required for the entire pilot end ionization process comes from the change in the structure of the storage capacitor between the thundercloud and the ground.
A structural capacitor C is formed between the charged cloud layer and the ground, and the ground and the cloud layer are two electrode plates of the capacitor. The total energy storage W of the structural capacitor C is as follows:
wherein w is the total energy storage of the structural capacitor, q is the total charge quantity, and C is the structural capacitor between the thundercloud and the ground.
The pilot end is simplified into a sphere with a radius of ro, and the capacitance between the upper pilot and the lower pilot is as follows:
where, ro is the equivalent radius of the pilot end.
Q is unchanged for a system region where the charge quantity is relatively stable before the breakdown discharge occurs. When the pilot moves forward, the distance L between the discharge electrodes becomes smaller, C increases, and the energy storage w of the whole system decreases. The reduced energy is used in the ionization process of air and is released in the form of luminescence.
Imaging and physics have demonstrated that the presence of an upward pilot on the ground is necessary to produce a penetrating discharge. In the atmosphere, a penetrating discharge is unlikely to form without an oncoming pilot. In a thunderstorm, we can see that some of the downstream pilot discharge that is developed to the ground is terminated without landing, because no effective upstream pilot is present in the local environment.
If a lightning receptor can generate longer ascending guide, the attraction effect is enhanced, and the longer the guide is, the larger the enhancing effect is. The supporter of the early discharge lightning receptor considers that it can emit the upward leader connected with the downward stepped leader in advance than the conventional lightning protection device, and as a result, can provide a larger protection range than the conventional lightning protection device of the same height.
However, if reliable upstream pilot discharge is to be implemented, the capacitance in the lightning receptor needs to be adjusted according to the lightning attribute in the range of the required protection area, but the lightning receptor is generally placed at a high position, the adjustment is inconvenient, the designed adjusting piece may cause charge accumulation, the upstream pilot discharge capacity of the lightning receptor is counteracted, and the problems of mutual interference of multiple lightning devices and how to accumulate enough energy to generate longer upstream pilot are also faced.
Disclosure of Invention
In order to solve the problems in the background technology, the invention provides a lightning receptor, which has the following specific technical scheme:
A lightning receptor comprises a shielding cover, a collector wheel, a mounting base, an upper needle bar arranged in the vertical direction, an upper polar plate and a lower polar plate which are in a disc-shaped structure and are in the same size, wherein a set gap is reserved face to face;
The top end of the upper needle bar is arranged on the top, the bottom end of the upper needle bar is fixed with the top of the upper polar plate, and the bottom of the lower polar plate is connected on the mounting base in a threaded manner and is communicated with the grounding wire;
the collector wheel is fixedly connected with the middle part of the upper needle bar through spokes and is fixedly connected with the mounting base through an insulating support rod, and the collector wheel is in unidirectional conduction with the upper needle bar in a direction that charges can only flow upwards from the collector to the polar plates in turn;
The shielding cover is fixed on the upper needle bar below the collector wheel, covers the upper polar plate and the lower polar plate in a non-contact manner, and is provided with a rainproof shielding part above the fixed part.
The design makes the lightning receptor utilize the insulation gap between the upper polar plate and the lower polar plate, and uses the upper metal discharge needle to absorb external charges and induce charge electric fields in cloud, so as to raise the electric potential of the discharge needle to higher electric potential, greatly reduce the field intensity of the tip of the top needle, eliminate continuous corona and accumulation of a large amount of space charges, and meet the basic requirements of the effective lightning receptor. Because the lower polar plate is in threaded connection on the mounting base, the height position of the lower polar plate can be changed through rotation, the adjustment of the distance between the upper polar plate and the lower polar plate is realized, and the external thread edge is internally arranged in the shielding case although the tooth point exists, so that interference caused by butt flashover can be avoided.
Preferably, the conductor is made of a metal material, wherein the upper polar plate and the lower polar plate are both made of tungsten-copper alloy with silver plated outer surfaces.
Preferably, the distance between the upper polar plate and the lower polar plate is 3-10mm.
Preferably, the spokes are semiconductor.
Therefore, the spoke can be used as a supporting piece and conduct current unidirectionally, components are reduced, and the overall reliability is improved.
Preferably, the electric power generator further comprises an inner bushing, wherein the bottom of the inner bushing is in butt joint with the top of the mounting base, the inner bushing is made of insulating materials and supports the inner surface of the shielding cover, one end of each insulating supporting rod is fixed with the collector wheel, and the other end of each insulating supporting rod is fixed with the mounting base through the shielding cover and the inner bushing.
The invention also provides a lightning protection device which comprises the lightning receptor.
Compared with the prior art, the invention has the following beneficial effects:
The lightning current amplitude is reduced, the rising steepness of the lightning current is reduced, and the electromagnetic shock impact is reduced.
The protection range is enlarged, the protection angle is larger than that of other traditional downlink lightning conductors, the protection angle of the traditional lightning conductors is between 30 and 40 ℃ and reaches 78 DEG, the protection area is enlarged, and the protection range exceeds that of the common lightning conductors by more than 10 times.
The protection performance is further improved, the shielding failure rate is greatly reduced, and the shielding failure rate is reduced to one thousandth of that of the traditional lightning arrester when the protection angle is 55 degrees.
The requirement on grounding resistance is reduced, the conventional lightning rod is required to be lower than the grounding resistance of 4Ω, the grounding resistance can be relaxed to 30Ω -100deg.Ω, and a large amount of metal materials, manpower and material resources are saved.
Multiple upward active discharges often cause the downward discharge process of the thundercloud to no longer occur or the discharge to be invisible (avoiding "ground flash"). After the lightning rod is installed, residents who are struck by lightning originally reflect the lightning, so that local thunder is reduced, far and less struck by lightning.
Drawings
FIG. 1 is a schematic cross-sectional view of a lightning receptor according to an embodiment of the invention;
FIG. 2 is a schematic diagram of a simulated test of a lightning receptor according to an embodiment of the invention;
In the figure, the upper needle bar is 1, the fastening nut is 2, the collecting wheel is 3, the insulating support rod is 4, the shielding cover is 5, the inner bushing is 6, the upper polar plate is 7, the lower polar plate is 8, the spokes are 9, the installation base is 10, the rain cover is 11, and the gap is 12.
Detailed Description
The present invention will be described with reference to the drawings and the embodiments thereof, in order to make the objects, technical solutions and advantages of the present invention more apparent. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. Based on this embodiment, all other embodiments that a person of ordinary skill in the art would obtain without making any inventive effort are within the scope of the invention.
As shown in fig. 1, the lightning arrester of the embodiment comprises a shielding cover 5, a collector wheel 3, a mounting base 10, an upper needle bar 1 arranged in the vertical direction, an upper polar plate 7 and a lower polar plate 8 which are in a disc-shaped structure with the same size and keep a set gap face to face, and a gap 12 between the upper polar plate 7 and the lower polar plate 8 is 3-10mm.
The upper needle bar 1, the shielding cover 5, the collector wheel 3, the upper polar plate 7 and the lower polar plate 8 are made of metal on the same axial lead, wherein the upper polar plate and the lower polar plate are made of tungsten-copper alloy with silver plated outer surfaces.
The top end of the upper needle bar 1 is arranged at the top, the bottom end of the upper needle bar is fixed with the top of the upper polar plate 7, and the bottom of the lower polar plate 8 is connected on the mounting base 10 in a threaded manner and is communicated with a grounding wire;
An inner lining 6 made of insulating materials is arranged in the shielding cover 5, the bottom of the inner lining 6 is abutted with the top of the mounting base, the inner surface of the shielding cover 5 is supported by the inner lining 6, and the upper polar plate 7 and the lower polar plate 8 are covered in a non-contact manner;
the collector wheel 3 is fixed with the middle part of the upper needle bar 1 through spokes 9 made of a semiconductor, the upper breadth of the collector wheel 3 is limited by the fastening nut 2, and the lower breadth presses the rain cover 11 to be abutted against the upper through hole of the shielding cover 5.
One end of the insulating support rod 4 is fixed with the collector wheel, and the other end is fixed with the mounting base 10 through the shielding cover 5 and the inner bushing 6.
The collector wheel 3 is in one-way conduction with the upper needle bar 1, and the one-way conduction direction is that charges can only flow from the collector wheel 3 to the upper polar plate 7;
the lightning receptor is arranged on a high pole for regional lightning prevention and control, and the lightning protection device forms another embodiment of the specification, namely a lightning protection device using the lightning receptor.
As shown in fig. 2, the device is scaled down according to a certain proportion, experimental authentication is carried out by simulating cloud layer discharge through a high-voltage power supply, no corona occurs in the tested lightning receptor, the normal reading of a nanoampere ammeter is zero, and the discharge gap in the tested lightning receptor can generate breakdown discharge under a certain high field intensity. When the oscillograph captures discharge pulses with a time constant of one microsecond level at intervals of several seconds to tens of seconds, the high-voltage electrode is charged and the monitoring nA ammeter has current change observation data of tens of nA, and the reading of the electrostatic voltage monitoring meter V is gradually increased after abrupt drop. The electric charge emitted by the lightning receptor is instantaneously sent to the upper electrode plate, and the electric charge on the upper electrode plate is instantaneously neutralized and exhausted by the upward pulse discharge. It may be that the current is too small and no striking discharge of the upper electrode plate occurs and no luminescence is observed between the electrodes. Since all meters are devices with second-order time constant damping, no transient changes are observed. However, the whole test has completely simulated the active discharge process of the lightning receptor in the lightning field, so that the process is called intermittent active ascending lightning process. The laboratory test of the active ascending lightning can not prove that the charge section actively released by the lightning rod is sent to the lightning cloud with the height of kilometers, but the verification that the lightning receptor can realize the ascending pilot discharge process is completed.
The device is arranged in a lightning stroke area, and through a plurality of non-coherent active discharges, the descending main discharge of thundercloud is not generated any more or is invisible, and according to the reflection of residents near the site of equipment installation points, the local thunder is reduced, far and less.
Therefore, the device can actively consume the energy stored by the thundercloud, is beneficial to the insulation protection of protected equipment, and is particularly suitable for special environments such as higher grounding resistance, high-rise and high-tower and the like.
It should be noted that the above-mentioned embodiments are merely preferred embodiments of the present invention, and the present invention is not limited thereto, but may be modified or substituted for some of the technical features thereof by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.