JPH0498782A - Lightning protection device for power line - Google Patents

Abstract

PURPOSE:To normally maintain a high level of withstand voltage, and to ensure predetermined movement at the time of receiving electric shock by providing a lightning protection element formed out of needle-shaped electrode and a series connection point of parallel resistance, which are connected with each other. CONSTITUTION:An upper flange 33a provided with a needle-shaped electrode holding member 39, a needle-shaped electrode 37, an upper main electrode 35, and a shield 34, on the lower surface, and a lower flange 33b provided with a lower main electrode 36 on the upper surface, are put on the upper end surface and on the lower end surface of an insulating cylinder 32, respectively, which is heated in a furnace, while both of the flanges 33a, 33b are connected airtight to both end surface of the insulating cylinder 32, and by sealing a vacuum container 31 into vacuum condition inside utilizing a sealing part 33c, a vacuum gap device is completed. Condensers 44, 45 are serially connected with each other with a connection conductor 49 sandwiched thereby, and this is held between supporting plates 47 and 48 fixed to the upper flange 33a and the lower flange 33b, and by connecting a connection plate 46 and a conductor 38 through the connection conductor 49, a lightning protection element is completed.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention was installed on the ground. It is installed between the above-mentioned above-mentioned above-mentioned above-mentioned tower and an overhead power transmission line that is suspended from a above-mentioned above-mentioned above-mentioned power transmission line which is suspended from a above-mentioned above-mentioned power transmission line through an insulator at a high position above the ground, which is at ground potential, and runs almost parallel to the ground. The present invention relates to a structure of a lightning arrester for a power transmission line that allows a lightning strike current to pass therethrough and then interrupts a current at an operating frequency flowing from the overhead power transmission line after the lightning current passes therethrough, thereby preventing a vM damage accident in a power transmission system.

[Prior Art] As a lightning arrester for this purpose, the one shown in FIG. 3 or 4 is known. In the case of Fig. 3, the lightning protection element 6, which has a resistance element mainly composed of zinc oxide built into the insulator tube, is fixed to the arm 1a of the steel tower 1 using a metal fitting 2.
The lower metal fitting 6a of this lightning protection element 6 is attached via
and the lower metal fitting 3ai of the suspension insulator 3 that suspends the power transmission line 4, and the electric rod &7 attached to it. It constitutes a line lightning arrester, and makes it possible to retransmit power even if the lightning arrester element 6 fails.

Figure 4 is dedicated to the installation environment of the lightning arrester, and the air gap Gr in Figure 3 is omitted to give a % protection I! A case is shown in which a lightning arrester for a power transmission line is configured with only element 6.

2. In these figures, 5a and 5b are conventionally attached. @This is an arc horn for protecting a suspended insulator, and it is based on the shape of the current path including the arc when flashing on the surface of the suspended insulator. By forming a guide path and allowing the arc to stay at its tip, the arc becomes a short arc away from the suspended insulator and serves to protect the suspended insulator from thermal damage. The operation of these lightning arresters will be explained below.

@2 In Figures 3 and 4, if there is no lightning arrester, for example, when tower I is struck by lightning, the ground potential of the entire tower rises due to the product of the lightning current and the tower pedestal ground resistance. If the difference with the ground potential of the power transmission line is large, the arc horn 5a
, 5b is closed, and a one-line ground fault current flows to the transmission line, and this ground fault current is interrupted by the circuit breaker at the substation, stopping the operation of transmission [H4] and causing a power supply failure. .

This means that power transmission @4 was struck by lightning and arc horn 5a.

The same thing applies when a flash occurs between 5b and 5b. However, as shown in Fig. 3, there are lightning arresters in which a lightning arrester element 6 is installed and an air gap G1 in series that discharges at a voltage lower than the arc horn, and a lightning arrester in which the air gear knob is omitted as shown in Fig. 4. If the device is installed in parallel with the arc horn, there will be no discharge between the arc horns, and the lightning current will be reduced by the lightning protection V! The AC/DC current at the operating frequency, so-called follow-on current, which flows through the power line 6 and flows from the transmission line side following this current, has a voltage of 0.5 to 1. The substation circuit breaker does not operate because it is shut off within 0 cycles. Therefore, power supply failure does not occur, and stable power supply can be achieved.

In this way, the conventional lightning arrester for power transmission lines uses a lightning arrester element that performs follow-on current interruption using a resistor element whose main component is zinc oxide as its series component, and is used for normal N-strike 2, for example, in the summer. As with lightning, the lightning current may reach hundreds of kA, but if the duration is about tens of microseconds and the amount of charge passing through it is about tens of coulombs, this is the case. However, when lightning strikes occur in the winter on the Sea of Japan coast, the lightning current is several hundred kA, which is equivalent to summer lightning, but the duration is a few milliseconds. , the amount of charge passing through reaches several hundred coulombs.

Since the amount of charge is about 1000% that of summer lightning, the amount of energy that can be absorbed is limited to a few tens of coulombs.A resistor element mainly made of zinc oxide cannot constitute a lightning arrester that can be used on power transmission lines on the Sea of Japan side. , and power supply failures still occur frequently.

As a countermeasure for this, we have developed a lightning arrester that has a large lightning current withstand capacity, can pass tens of thousands of coulombs of charge easily, and can interrupt the following current in 0.5 to 1.0 cycles. The same inventor as the present inventor has proposed a vacuum gap device having a discharge gap in a vacuum container as a series component through which lightning current passes (see Japanese Patent Laid-Open No. 1-304679).

According to this proposal, a vacuum gap device with series components consists of an upper flange 17a and a lower flange 17b, each of which hermetically seals both end faces of an insulating cylinder lb, as shown in FIG. are inserted through the upper electrode 18 and the lower electrode 19 to face each other in the axial direction. In this example, these electrodes each have a disk shape of the same shape and size fixed to the tip of a metal round rod.The discharge gap formed by both electrodes is at the same potential as the upper flange 17a. It is surrounded by a certain cylindrical metal shield 221, and prevents the metal vapor generated from the disc-shaped electrode from depositing on the inner surface of the insulating cylinder 16 at the time of 1 Lvr flow in the discharge gap, thereby preventing the operation of the vacuum gap device. This prevents the insulation of the half-insulating cylinder 16 from deteriorating. In addition, the sign addition in the figure indicates a metal bellows,
This is used when adjusting the discharge gap length in a factory test, and after the adjustment is completed, the lower electrode 19 is fixed to the lower 7 flange 174k. Further, reference numerals 21, Z3, and 24 respectively indicate a sealing part for sealing off the inside of the vacuum container formed by the insulating tube 16, the upper flange 17a, and the lower flange 17b, a terminal formed on the upper electrode 18, and a lower electrode. A terminal formed at 19 is shown.

As is well known, a discharge gap in a high vacuum with a degree of vacuum of 10 Hg or less exhibits an extremely high constant discharge voltage regardless of the pressure.
When a uniform electric field of 37 kV is formed, the discharge voltage is 37 kV. Therefore, it is required when the transmission voltage is between 66 kV and 154 kV. For a discharge voltage of about 270 kV to 630 kV or less, a gap length of about 20@s or less can be used assuming that a quasi-equal electric field is formed between the gap electrodes. Also, the lightning current during discharge is a discharge current in a vacuum.

Ig is not limited in size either. Furthermore, since such a large current arc has the effect of shrinking its diameter due to its own pinch effect, it is possible to easily pass a lightning strike current with a large peak value and a long duration in a vacuum vessel of relatively small diameter and practical dimensions. I can do it. Furthermore, since the insulation recovery after passing the current zero point in vacuum is extremely fast, the AC current interrupting ability can be several thousand amperes even with the simplest configuration of the gap. Then, even larger current can be interrupted. In a power transmission system with a transmission voltage of 66 kV to 154 kV, the single wire ground fault current in two lines is less than several hundred amperes, so it can be interrupted by a gap electrode with a simple structure. Therefore, by using a discharge gap device with a long external insulation distance but a relatively small diameter as a series component of a lightning arrester, an economical and lightweight lightning arrester for a power transmission line with a large amount of charge that can pass through is made possible. In addition, when the vacuum gap device configured in this way is used in series with the air gap Gt as shown in FIG. If a capacitor is connected, almost all the voltage applied between the power transmission line 4 and the steel tower L will be applied to the air gap G1, so the gap length setting of the air gap G can be done independently of the vacuum gap device. This provides administrative convenience when configuring a lightning arrester whose components are manufactured by different manufacturers. In addition, if a lightning strike to a power transmission line crosses two or three wires, the magnitude of the follow-on current will be the magnitude of the short circuit current, and the insulation recovery of the vacuum gap will be small. A gap electrode is built-in in case a multi-line lightning strike is expected. By combining short vacuum gap devices in multiple stages and connecting capacitors of the same capacitance in parallel to each vacuum gap device to equalize the voltage shared by each vacuum gap device, multi-wire lightning strikes in winter can be prevented. It becomes possible to create a lightning arrester that can withstand Note that this multi-stage vacuum gap device is
As shown in the figure, when air gap GJs are used in series, the series capacitance of the capacitors connected in parallel to each unit vacuum gap device is the same as the parallel capacitor of the single vacuum gap device mentioned above. [Problem to be Solved by the Invention] A lightning arrester for power transmission lines using a vacuum gap device as a series component is currently being developed as shown in Figure 6. , vacuum camping equipment 8
, a lightning protection element 10 constituted by a capacitor 9 connected in parallel to the vacuum cap device, and a rod electrode 7a.
, 7b, and the air gap G1 formed between the lightning arrester and the air gap G1.
If the discharge voltage is set to be equal to the positive discharge voltage, the operation of the lightning arrester during a lightning strike will be almost simultaneous, but first, the discharge gap G1 in the vacuum cap device 8 will be discharged, and then the discharge gap G2 in the vacuum cap device 8 will be discharged. This is done so that the lightning current passes through the discharge and the follow-on current following this passage is interrupted within 0.5 to 1.0 cycles at the discharge gap G2, so that the substation circuit breaker does not operate. From this operating principle, the discharge voltages of the individual gaps of Go, G+, and Gz are Vo, Vl, and Vz.
is set so that V2 < Vl < VO.

However, the discharge gap G2 of the vacuum gap device 118 is
It is formed by coaxially opposing two disk-shaped or spherical electrodes, and is designed so that the electric field in the gap has an equal or quasi-equal distribution.
As shown in , when the dispersion of the discharge voltage is large and the rise of the lightning voltage waveform is steep, the discharge voltage rises rapidly, and the gap length is set to the value necessary for blocking the sand flow.
In the case of a steeply rising lightning voltage waveform with a discharge time shorter than point P in Figure 7, the discharge voltage becomes higher than the discharge voltage in the air gap Gt shown by ■ in the figure, and the lightning arrester is activated. Predetermined operations are no longer performed.

The object of the present invention is to provide a series component of a lightning arrester for a power transmission line with a flat group 1 m in which the discharge voltage does not exceed the discharge voltage of the air gap, regardless of the steepness of the rise in the lightning voltage waveform. In addition to showing the pressure, there is little variation so that it can be used alone as a lightning arrester without being used in combination with an air gap.

An object of the present invention is to provide a lightning protection element configuration that exhibits stable Group 1 characteristics.

[Means to solve the problem]

In order to solve the above-mentioned problems, in the second aspect of the present invention, a lightning arrester for a power transmission line is configured such that a slight gap is formed between two main electrodes facing each other in a vacuum container and one of the main electrodes. T
Ru. A parallel capacitor comprising a needle-shaped electrode insulated from the main electrode, and two capacitors connected in series outside the vacuum container in parallel with a king gap formed by the two king poles. , or a parallel resistance formed by connecting two resistors in series is provided, and a series connection point of the needle electrode and the parallel capacitor, or a series connection point of the needle electrode and the parallel resistance is connected. It is assumed that the structure has a lightning protection element as a single-row component through which the Wst flow passes.

The electrode configuration in the vacuum vessel of the lightning protection element with this configuration is such that the two opposing main electrodes have opposing surfaces formed in a spherical or circular planar shape, and one main electrode has a small portion at the center of the opposing surface. A needle-shaped electrode having a hole formed therein and forming a minute gap between it and one of the main electrodes is located on the back side of the opposing surface substantially on the axis of the main electrode in which the small hole is formed, and its tip is located on the same side as the opposite side of the main electrode. It is preferable to arrange it so that it is located substantially in the same plane as the in-plane notch.

[Effect: By configuring the lightning element in this way, the ia tortoise pressure can be avoided following the discharge of the air cap Gl during a lightning strike! When applied to the element, two capacitors or two resistors are connected between the needle-shaped electrode in the vacuum vessel of the lightning protection element and one main electrode that forms a minute gap between this needle-shaped electrode. Sparks are generated by applying divided voltages. This spark has the effect of supplying ions to the discharge gap formed by the two main electrodes and the effect of exciting the gas molecules in the gap due to irradiation, so discharge easily occurs between the main electrodes, and the discharge voltage due to only the main electrodes In comparison, as the tear 1 voltage decreases, the dispersion of discharge becomes significantly smaller by 1, and stable discharge can be realized.

In addition, as a t-pole structure in the vacuum vessel in a lightning arrester element configured as described above, a needle-shaped electrode is formed at the center of the opposing surface of the main electrode formed in a spherical or circular planar shape. From behind the face facing the small hole, almost III of King t'&
By making the electrode structure fixed so that it looks along the NM and its tip is located in the same plane as the center of the opposing surface, one main electrode can be fixed without disturbing the electric field distribution in the discharge gap between the main electrodes. This makes it possible to form a minute gap between the electrode and the electrode.

A high withstand voltage can be maintained at all times between the tr+ poles.

〔Example〕

FIG. 1 shows an embodiment of a lightning protection element configuration according to the present invention.

A metal block 41 is attached to the lower surface of the metal upper flange 33a that airtightly seals the end surface of the upper blade of the porcelain insulator 32.
A thin insulating cylinder 40 made of A6 is installed on the upper and lower surfaces of the
, 42 are airtightly joined to each other at a flange portion formed on the insulating tube 40,
A conductor is inserted inside the insulating tube and the metal block 4 is inserted.
Along with being screwed into 1.

According to the internal information of Insun Tsutsusha, a needle-shaped electrode 37 having a screw and a static fitting portion with no play formed at the upper end thereof is inserted and screwed into the metal block 41.

Due to the fitting portion of the needle-like electrode in the statically engaged state, the needle-like electrode is reliably held on the insulating cylinder 42 over its entire length. Fitting the upper main electrodes, each of which has a spherical opposing surface and a small hole in the center of the opposing surface, from below onto this needle-shaped electrode holding member 39 using a guide section around the small hole; The needle electrode 37 is positioned at the center of the small hole. The dimensions of the related parts are set so that when the upper raw electrode is attached to the lower surface of the upper flange 33a, the tip of the needle-like electrode leg is approximately in the same plane as the center of the opposing surface of the upper main electrode. Furthermore, a shield is provided on the lower surface of the upper flange 33a concentrically with the upper main electrode, and an upper terminal (
3) is fixed.

A lower main electrode holder is fixed to the upper surface of the metal lower flange 33b which airtightly seals the lower end surface of the insulating cylinder support made by Nagiki, and a lower terminal 5 is fixed to the lower surface. An air gap Gl (@Fig. 3) is provided in advance for this lower terminal group.

The metal II layer constituting one electrode (see section 6) is bath-welded.

In this way, the needle-like electrode holding member 39. Needle electrode 3
7. Apply the upper 7 flange 33a equipped with the upper main electrode A and the shield A and the lower 7 flange 33b equipped with the lower main electrode 33 on the upper surface to the upper and lower end surfaces of the insulating tube 32, respectively, in the furnace. Heat to 7/33a.

33b are hermetically joined to both end surfaces of the insulating tube 32, respectively,
The vacuum gap device is completed by sealing the inside of the vacuum container 31 to a vacuum using the sealing cutter C.

Next, two pieces of capacitor material 45 are connected in series with the connecting conductor tube in between, and this is connected to the upper flange 33a.

The lightning protection element is completed by holding it between supporting plates 47 and 48 fixed to the lower 7 flange 33b and connecting the connecting plate wear and the conductor trace via the connecting conductor 49.

The discharge voltage percentage between the upper and lower main electrodes & 36 when an impact voltage is applied as a lightning voltage between both terminal pieces 51 of the W escape element configured in this manner is I! It is indicated by the symbol ■ in Figure 2. The dispersion is significantly smaller compared to ■, where only 36 shows a discharge voltage characteristic of E, and the discharge voltage is always below the air gap G1, regardless of the steepness of the rising part of the shock voltage. It's spinning.

Furthermore, substantially the same experimental results as above were obtained when a parallel resistor was used instead of the parallel capacitor of the lightning protection element.

〔Effect of the invention〕

As described above, in the present invention, a lightning arrester for a power transmission line is configured such that a minute gap is formed between two main electrodes facing each other in a vacuum container and one of the main electrodes. A parallel capacitor comprising a needle electrode insulated from the main electrode, and two capacitors connected in series outside the vacuum container in parallel with a main gap formed by the two main electrodes.

Alternatively, a parallel resistor formed by connecting two resistors in series is provided, and a series connection point between the needle electrode and the parallel capacitor, or a series connection point between the needle electrode and the parallel resistor is connected. Since the lightning protection element is configured as a series component through which the lightning current passes, it is possible to pass the lightning current with energy such as the winter type where the charge reaches a maximum of coulombs without any problem, and the operating frequency current that follows this passage. is reliably interrupted within 0.5 to 1.0 cycles, and the lightning voltage j? following the discharge of the air gap G+ during a lightning strike. When the i-element is stamped, two capacitors or two capacitors are connected between one needle-shaped pole in the vacuum vessel of the lightning protection element and one main electrode that forms a minute gap between the needle-shaped pole and the needle-shaped pole. A voltage divided by two resistors is applied to generate a spark, and due to the ion supply effect of this spark and the excitation effect of the scum molecules in the discharge gap caused by the irradiation, a discharge is easily generated between the main electrodes. Compared to the discharge voltage generated by only the main electrode, the discharge voltage is lowered, and variations in discharge are significantly reduced, making it possible to realize stable discharge.

This ensures that the discharge voltage condition in the lightning arrester for power transmission lines according to the present invention: V2 < Vl < VO is always maintained.

In addition, since the needle-like electrode was arranged on the back side of the opposing surface on the @ line of the main electrode in which the small hole was formed, and the tip was located in almost the same plane as the center of the opposing surface of the main electrode, It becomes possible to form a minute gap with one main electrode without disturbing the electric field distribution in the inter-electrode discharge gap, and a high withstand voltage can be maintained at all times between the two main electrodes.

As a result of the above, the withstand voltage is maintained high at all times, and the desired operation can be performed reliably in the event of a lightning strike.

1! 1 with a large capacity! It has become possible to create a line lightning arrester.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing the operation η of the lightning protection element structure according to the present invention, Fig. 2 is a diagram comparing and showing the release pressure characteristics of the conventional vacuum cap device 2 and the vacuum cap device of the present invention, and Fig. 3 And Figure 4 includes conventional gunpowder! Figure 5 is a! ! A vertical cross-sectional view showing an example of the configuration of a lightning protection element proposed to solve the problems of one element in the lightning protection element shown in Fig. 3 or Fig. FIG. 2 is an explanatory diagram for explaining problems when configuring a lightning arrester for a power transmission line. 1... Steel tower, 4... Power line, 6. lO...Lightning protection element. 31...Vacuum vessel, ah...upper main electrode (main electrode). I: Lower main electrode (main electrode), 37: Needle electrode. Super...parallel capacitor%4,45...capacitor.

Claims (1)

[Scope of Claims] 1) Between the steel tower and an overhead power transmission line that is suspended at a high position above the ground and runs substantially parallel to the ground via an insulator from a steel tower that is erected on the ground and is at ground potential. A transmission system that responds to the lightning strike of the installed overhead power transmission line or steel tower by allowing the lightning current to pass therethrough, and following this passage, interrupts the current at the operating frequency flowing from the overhead power transmission line to prevent lightning damage accidents in the power transmission system. In the lightning arrester for power lines, the lightning arrester for power lines includes:
Two main electrodes facing each other inside the vacuum container, and a needle-shaped electrode insulated from the main electrodes forming a minute gap between the two main electrodes, and the A lightning arrester comprising a parallel capacitor formed by connecting two capacitors in series in parallel with a main gap formed by two main electrodes, and connecting the needle-shaped electrode to a series connection point of the parallel capacitors. A lightning arrester for a power transmission line, comprising the element as a series component through which the lightning current passes. 2) The above-mentioned overhead power transmission line is installed between the above-mentioned above-mentioned tower and an overhead power transmission line that is suspended from a above-ground steel tower at ground potential via an insulator and runs substantially parallel to the ground surface. Or, in a lightning arrester for a power transmission line, which responds to a lightning strike on a steel tower and allows the lightning current to pass through, and after this passage, interrupts the current at the operating frequency flowing from the overhead power transmission line to prevent lightning damage accidents in the power transmission system, The lightning arrester for power transmission lines is
Two main electrodes facing each other inside the vacuum container, and a needle-shaped electrode insulated from the main electrodes forming a minute gap between the two main electrodes, and the A lightning arrester comprising a parallel resistor formed by connecting two resistors in series in parallel with a main gap formed by two main electrodes, and connecting the needle-shaped electrode to a series connection point of the parallel resistors. A lightning arrester for a power transmission line, characterized in that the element is a series component through which the electric shock current passes. 3) In the lightning arrester according to claim 1 or 2, the two main electrodes facing each other in the vacuum vessel have opposing surfaces formed in a spherical or circular planar shape, and one of the main electrodes has a A small hole is formed in the center of the opposing surface, and a needle-like electrode that forms a small gap with one of the main electrodes is located on the back side of the opposing surface approximately on the axis of the main electrode in which the small hole is formed, and its tip is A lightning arrester for a power transmission line, characterized in that the lightning arrester is arranged so as to be located substantially in the same plane as the center of the opposing surface of the main electrode.