JPS6360606B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a particularly strong lightning arresting effect to lightning rods (lightning rods as defined in JIS A4201), such as overhead ground wires, provided to protect power equipment and buildings from lightning. It relates to a device for.

Conventionally, in power transmission and distribution systems in areas where lightning occurs, one or two overhead ground wires have been installed at the top of the lines to protect the system from direct lightning strikes. The action and effect of lightning shielding using overhead ground wires is that lightning strikes on power transmission lines are received by overhead ground wires and the lightning charge is guided to the ground, thereby preventing the lines from flashing over. This means that you can continue driving. However, in reality, it is not uncommon for railway lines to be struck by lightning even though overhead ground wires are installed. The present invention has been made in view of this point, and it is an object of the present invention to provide a device that further perfects the lightning protection effect of lightning rods by imparting a particularly strong lightning arresting effect to lightning rods such as overhead ground wires. It is something to do. The present invention will be clarified by explaining the principles, examples, and experimental results of the present invention in detail using the drawings.

FIG. 1 is a schematic diagram showing the principle of the present invention. In FIG. 1, reference numeral 1 denotes an overhead ground wire, which is grounded to the earth 3 through a ground wire 2. Reference numeral 4 denotes a conductor of the device of the present invention, which is provided close to the overhead ground wire 1 and insulated from the overhead ground wire 1. Also, in the same figure,
A step leader 6 is shown descending from a thundercloud 5 and the potential near its tip becomes _VL . From thunder cloud 5 to steps leader 6 as shown
comes down and the potential near its tip is V _L , the aforementioned conductor 4 receives electrostatic induction such that it has a potential of V _F.

Now, the capacitance between the reader 6 and the conductor 4 is
If C _LF is the capacitance between the conductor 4 and the overhead ground wire 1, then C _FG is the capacitance between the conductor 4 and the overhead ground wire 1, then the following relationship generally holds: V _F =C _LF /C _LF +C _FG ·V _L (1). By the way, next step leader 6
, an upward leader is generated from the overhead ground wire 1 near the conductor 4 and a main discharge is generated, but before the upward leader is generated, the state is such that C _LF ≪C _FG ...(2) be. Therefore, from equations (1) and (2) above, V _F C _LF /C _FG・V _L ...(3).

That is, the potential V _F of the conductor 4 is approximately equal to the capacitance C _LF between the reader 6 and the conductor 4 and the step leader 6.
It is proportional to the product of the potential V _L near the tip. The closer the tip of the step leader 6 is to the ground, the more the value of _CLF increases. On the other hand, the rate of change in the value of V _L is relatively small. Therefore, the value of V _F increases as the tip of the step leader 6 approaches the ground surface. When the potential V _F of the conductor 4 rises in this manner, a strong electric field is generated intensively at the end of the conductor 4, and first, a discharge occurs between the end of the conductor 4 and the overhead ground wire 1. This discharge is triggered and an upward leader (so-called welcoming discharge) is generated upward from the location where the discharge occurs, and this combines with the downward step leader 6 to complete the lightning discharge.

To summarize the above, if a conductor 4 insulated from the overhead ground wire 1 is provided close to the overhead ground wire 1, the potential of the conductor 4 will increase as the downward step leader 6 advancing from the thundercloud 5 approaches the ground surface. rise,
First, a tonguing discharge occurs between the conductor 4 and the overhead ground wire 1. The device of the present invention actively utilizes this effect to guide lightning discharge to the location where the tonguing discharge occurs by generating an upward leader earlier than other locations due to the ionization effect of this discharge. This is an attempt to perfect the lightning shielding effect of overhead ground wires.

FIG. 2 is a sectional view showing an embodiment of the present invention. In the figure, 10 is an overhead ground wire, and in the device of this embodiment, the tubular conductor 40 has an insulator 70 that is shorter in the axial direction of the overhead ground wire 10 than the conductor 40 and has a substantially uniform thickness. It is arranged so as to surround a certain section of the outer surface of the overhead ground wire 10 through the ground wire. In the apparatus of the present invention having such a configuration, when a step leader from a thundercloud approaches the overhead ground wire 10, the tubular conductor 40 (particularly its end 41 ) and the overhead ground wire, and the ionizing effect of this discharge leads to a lightning discharge when the triggering discharge occurs.

The present inventors conducted experiments as described below to compare the lightning arresting effects of an overhead ground wire equipped with the lightning arrester of the present invention and a normal overhead ground wire, and obtained remarkable results.

Figure 3A shows a simulated overhead ground wire (outer diameter
It is a 10mm stainless steel pipe (hereinafter referred to as the overhead ground wire 11). Further, FIG. 3B shows a conventional overhead ground wire simulator (stainless steel pipe with an outer diameter of 10 mm, hereinafter referred to as the overhead ground wire 12) whose performance was compared with the overhead ground wire shown in FIG. 3A. In FIG. 3A, parts corresponding to those in FIG. 2 are given the same reference numerals, and detailed explanation of the device itself will be omitted. In addition, in this experiment, the symbols representing the dimensions of each part were determined as follows.

Dl: Length of the lightning arrester conductor in the direction of the overhead ground wire d: Length of overhang from the insulator at the end of the lightning arrester conductor a: Thickness of the insulator g: Distance between each lightning arrester conductor Figure 4 shows the Overhead ground wire 1 shown in Figure 3 A and B
1 and 12 are diagrams showing an electrode system in this experiment configured by arranging electrodes 1 and 12. 5 is a view of the electrode system in FIG. 4 viewed from the side of the overhead ground wire 11, and FIG. 6 is a view of the electrode system seen from the side of the overhead ground wire 12. In Figures 4 to 6, a rod electrode 60 with a length Hl = 500 mm is provided so as to hang down from a flat plate electrode 50 which has sufficient capacitance and is provided at a height H = 2000 mm from the ground surface. There is. The conventional simple overhead ground wire 11 and the overhead ground wire 12 according to the present invention are at a constant interval D.
= 500mm, and is stretched at a height of Hg = 1000mm from the ground surface 3. As is clear from FIG. 4, the rod electrode 60 is located at a position where the vertically downward extension from its tip passes through the midpoint of one line segment connecting the center lines of both the overhead ground wires 11 and 12. (that is, at a position where the distance from the tip of the rod electrode 60 to both overhead ground wires 11 and 12 is equal).

In the configuration of the electrode system shown in FIGS. 4 to 6, the dimensions of each part of the overhead ground wire 11 on which the lightning arrester shown in FIG. 3A is arranged were set to various values. The experimental results are shown in Figures 7a to 1. In Fig. 7 a to l, E: Applied voltage to the rod electrode 60 (2 x 40 μS negative polarity impact voltage) V ₅₀ : 50% flashover voltage in this electrode system (approximately 400 kV) V _FO : Flashover voltage t: Time from voltage application to flashover Dl: Length of the lightning arrester conductor in the direction of the overhead ground wire d: Length of overhang from the insulator at the end of the lightning arrester conductor a: Thickness of the insulator g: Between each lightning arrester conductor Interval flashing number: When voltage E is applied to the rod electrode 60 50 times, the overhead ground wire 11 or 12 or 11,1
2. Number of flash faults to both overhead ground wires 〇: Number of flash faults to the overhead ground wire 11 ×: Number of flash faults to the overhead ground wire 12 △: Number of flash faults to both the overhead ground wires 11 and 12 As is clear from the experimental results shown in Figures 7a to 7l, the lightning arresting effect of the overhead ground wire equipped with the lightning arrester of the present invention is extremely large.

In the above description, only an embodiment having a tubular conductor 40 provided close to the overhead ground wire 10 as a lightning rod through an insulator 70 has been described in detail. In addition to implementation, it can be implemented as any type of lightning arrester, such as one in which a conductor installed close to and insulated from the overhead ground wire has a protrusion protruding toward the overhead ground wire. It is something. Further, the lightning rod to which the present invention is applied is not limited to the above-mentioned overhead ground wire, but the present invention can also be applied to a normal lightning rod having a protrusion. In this case, a conductor insulated from the needle may be provided close to the top of the needle.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the principle of the present invention, Fig. 2 is a sectional view showing an embodiment of the invention, and Figs. 3A to 6 show an overhead ground wire equipped with the device of the present invention and a conventional Figures 7a to 7l are diagrams used to explain an experiment to compare the lightning arresting effect with an overhead ground wire, and are diagrams showing the results of this experiment. 10...Overhead ground wire, 40...Conductor, 70...Insulator.

Claims (1)

[Scope of Claims] 1. A lightning arrester having a conductor provided close to a conductor portion of a lightning rod and insulated from the conductor portion of the lightning rod. 2. The lightning arrester according to claim 1, wherein the conductor portion of the lightning rod is an overhead ground wire.