JPH0654621B2 - Lightning arrester device for overhead power lines - Google Patents

Description

The present invention relates to a suspension insulator device for overhead power transmission lines, such as a suspension insulator device, a tension insulator device, and a V suspension insulator device.

(Prior Art) Generally, when a lightning surge voltage is applied to a transmission line, a surge arrester device for a transmission line has been proposed that promptly discharges the surge current and interrupts a subsequent current that occurs thereafter to prevent a ground fault. ing. As the lightning insulator device, the sixth
As shown in the figure, the power transmission line 10 is supported by the support arm 2 of the steel tower 1 via the support insulator 7, and the current limiting element 20 mainly made of zinc oxide having a nonlinear voltage-current characteristic is incorporated. A predetermined discharge gap is provided between the grounding-side discharge electrode 18 that supports the lightning protection insulator 15 and is attached to the lower end of the lightning protection insulator 15, and the charging-side discharge electrode 19 that is attached to the power transmission line 10 side. In the transmission line lightning arrester device provided with G, the relationship between the distance of the air insulation gap G ₀ of the support insulator 7, that is, the insulation gap length Z _0, and the distance of the discharge gap G, that is, the discharge gap length Z is shown. In some devices, the insulation gap length and the discharge gap length were set so that Z / Z ₀ ≦ 0.5. (See Japanese Patent Laid-Open No. 60-262312) (Problems to be Solved by the Invention) However, in the conventional lightning arrester device, the power transmission line 1 is used.
When a lightning surge voltage is applied to 0, the discharge gap G cannot always be flashed over, and the air gap G ₀ of the supporting insulator is flashed over.
It was not possible to prevent a ground fault accident. That is, in the comparatively low transmission voltage class of 66 to 77 KV, the above-mentioned relation of "Z / Z ₀ ≤0.5" was satisfactory, but in the transmission line of the high voltage class of 154 KV or more, the experimental result was obtained. As a result, it was found that the gap between the discharge electrodes does not necessarily cause harshover.

Conventionally, when the current limiting element 20 is interposed, the overall flashover voltage of the discharge gap G and the current limiting element 20 is about 2 to 2 as compared with the case where the current limiting element 20 is not used. It is considered to be increased by 30%, and since only the dimensional relationship between the insulating gap length Z ₀ on the supporting insulator 7 side and the discharge gap length Z is used as an element, the characteristic peculiar to the current limiting element 20 is ignored. As a result, it is presumed that the flashover does not occur in the discharge gap G with the desired probability (normally 50% probability) as described above.

By the way, assuming that the flashover voltage due to the lightning impulse in the insulation gap G ₀ on the supporting insulator 7 side is Vg _0, and the flashover voltage due to the entire lightning impulse including the current limiting device 20 and the discharge gap G is Vt, Vg It has been known that it is necessary to satisfy the condition of ₀ > Vt. It was experimentally known that it is necessary to set Vg ₀ > 1.3Vt in view of safety.

However, it has not been clarified what the flashover voltage Vt actually is.

It has been confirmed that in the conventional lightning protection insulator device, the current limiting element 20 can only be grasped as an insulator or as a conductor, and an appropriate insulation design cannot be made under such a premise. .

The present invention was made based on this finding as a result of an experiment conducted to find out the cause of the above-mentioned problem, as a result of what element the flashover voltage Vt depends on.

Configuration of the Invention (Means for Solving the Problems) In order to solve the above problems, the present invention supports a transmission line on a support arm of a steel tower via a support insulator, and a grounding side and Disposing the discharge electrodes on the charging side to face each other, and providing a current limiting element mainly composed of zinc oxide having a non-linear voltage-current characteristic on at least one discharge electrode side of the both discharge electrodes, In a lightning arrester device for an overhead power transmission line having a function of interrupting a subsequent flow when a lightning surge enters the power transmission line, a lightning impulse / flashover voltage in an aerial insulation gap of the support insulator is set to Vg _0, and When the operation start voltage of the current limiting element is Vb, the lightning impulse in the air discharge gap when the current limiting element is electrically short-circuited
Means for setting the air insulation gap length of the support insulator, the air discharge gap length between the discharge electrodes, and the electrical characteristics of the current limiting device such that Vg ₀ > Vb + Vg when the flashover voltage is Vg. Is taking.

(Operation) Now, when a lightning surge voltage is applied to the transmission line, the surge current flashes over the air discharge gap to flow to the source element, reaches from the support arm to the tower, and is discharged to the ground. At this time, the lightning surge flashover voltage Vg ₀ of the air insulation gap on the supporting insulator side is the lightning surge flashover of only the series air discharge gap obtained by short-circuiting the operation starting voltage Vb of the current limiting element. Since it is larger than the voltage Vt added with the voltage Vg, the lightning surge current does not flash over in the aerial insulation gap, but certainly in the discharge gap. As a result, the reliability of the lightning arrester device with respect to the lightning surge current processing is increased, and the tower is downsized by the rational design.

(Embodiment) An embodiment embodying the present invention will be described below with reference to FIGS. 1 to 5.

As shown in FIG. 5, a connecting metal fitting 3 is fixed to the tip of the supporting arm 2 adhered to the steel tower, and a suspending insulator 6 is connected in series to the connecting metal fitting 3 via a U clevis link 4 and a horn mounting metal fitting 5. A support insulator 7 connected to the above is supported swingably in the line direction and the orthogonal direction. The power transmission line 10 is supported on the horn mounting metal fitting 8 at the lower end portion of the support insulator 7 via a connecting link 9 and an electric wire clamp 11. Arcing horns 12 and 13 are attached to the horn mounting brackets 5 and 8 for reducing damage caused by creeping flash on the support insulator 7. A predetermined air insulation gap G ₀ (insulation gap) is provided between the arcing horns. The length Z ₀ ) is provided.

A mounting bracket 14 made of a conductor is laterally fixed to the tip of the support arm 2 with bolts, and a lightning arrester 15 is fixed to the tip of the bracket 14 with a grounding electrode metal fitting 16 by bolts. There is. or,
A horn-shaped ground-side discharge electrode 18 is supported on the electrode-side electrode fitting 17 at the lower end of the lightning protection insulator 15.

On the other hand, the horn mounting member 8 has a horn-shaped discharge electrode 19 on the charging side, which is substantially horn-shaped in the line direction, cantilevered by a bolt, and a predetermined air gap is provided between the discharge electrode 19 and the discharge electrode 18. A discharge gap G (discharge gap length Z) is provided.

The lightning protection insulator 15 includes a withstand voltage insulating cylinder (not shown) formed in a cylindrical shape by a tension-resistant material such as FRP, and a zinc oxide (ZnO) housed therein, which has a nonlinear voltage-current characteristic.
A current limiting element 20 mainly composed of the above, the electrode-shaped metal fittings 17 and 16 on the power-supply side and the ground side, which are cap-shaped and fitted and fixed to both ends of the pressure-proof insulating cylinder, and further provided on the outer periphery of the pressure-proof insulating cylinder. And a rubber mold 21. In addition,
An arcing ring (not shown) is provided on both of the electrode fittings 17 and 16 of the lightning protection insulator 15 to reduce damage when the rubber mold 21 flashes over the surface.

Here, the background of how the lightning protection insulator device of the present invention was created will be described.

The relationship between the air insulation gap length G _{0 of the} support insulator 7 and the flashover voltage Vg ₀ due to a lightning impulse is as follows.
As shown in the figure, it is conventionally known that the flashover voltage Vg ₀ linearly increases as the insulation gap length Z ₀ increases.

Further, as shown in FIG. 3, the discharge gap length Z of both the discharge electrodes 18 and 19 in the state where the current limiting element 20 is short-circuited.
And the lightning impulse flashover voltage Vg across the discharge gap G, it has been known that the flashover voltage Vg increases linearly in proportion to the increase of the discharge gap length Z. .

Furthermore, when the current limiting element 20 is viewed alone, the element 20
Current Ib flowing through the device and the operation start voltage Vb of the device 20.
The relationship with (voltage determined by each current limiting element 20 regardless of lightning impulse) is shown in FIG. 4, where the current Ib is constant, for example, the first turning region of 1 mmA to 20 mmA. When the current Ib exceeds the second turning region, the operation start voltage Vb becomes substantially constant up to a large current region of the second turning region of several tens of A to several KA, and when the current Ib exceeds the second turning region, the voltage Vb increases again. This is also known in the art.

However, among the three rules shown in FIGS. 2 to 4 described above, it has not been clarified at all what relationship they have in the actual lightning arrester device.

Therefore, in order to understand how the entire lightning impulse / flashover voltage Vt on the side of the current limiting element 20 having the discharge gap G is determined, an experiment was conducted,
The data shown in FIG. 1 were obtained. From this graph, it was found that increasing the discharge gap length Z linearly increased the entire lightning impulse flashover voltage Vt.

In the past, it was possible to speculate that the voltage Vt would increase as the discharge gap length Z was increased, but in the present invention, it was experimentally verified how this actually increases. It was created with the idea that there is an important law in it. That is, the fact shown in the graph of FIG. 1 is that in the region where the operation starting voltage Vb is substantially constant, the lightning impulse / flashover voltage Vg of the discharge gap G is added to the operation starting voltage Vb for the entire lightning. Impulse flashover voltage Vt
I found the law that is almost equal to.

Therefore, the inventors of the present application added the lightning impulse / flashover voltage Vg at the discharge gap G to the operation start voltage Vb of the current limiting element 20 itself based on the law discovered as a result of the above-described experimental verification. If the lightning impulse / flashover voltage Vg ₀ on the supporting insulator 7 side is made larger than the voltage, that is, if the discharge gap length Z and the insulation gap length Z ₀ are set so that the relationship of Vg ₀ > Vb + Vg is established, In the actual pillar state,
It has been conceived that, when a lightning surge current enters the device, it is possible to reliably perform flashover in the discharge gap G with a predetermined probability.

In other words, according to the present invention, the operation starting voltage V of the current limiting element 20 is
Introducing the element b and focusing on the fact that the operation start voltage Vb acts as a kind of switch in the relationship between the operation start voltage Vb and the flashover voltage Vg of the air discharge gap G, This is fundamentally different from the conventional idea of grasping the flow element 20 as an insulator or a conductor at the end.

Next, the following facts proved that the present invention was correct as a result of experiments.

The following results were obtained in an apparatus in which the insulating gap length Z ₀ of the supporting insulator 7 was about 790 mm, the discharge gap length Z was about 450 mm, and the relationship of Z / Z ₀ > 0.5 was established. That is, the operation start voltage Vb is about 120
When KV, the lightning impulse flashover voltage Vg _{0 of the} support insulator 7 is 490 KV, and the lightning impulse flashover voltage Vg of the discharge gap G when the current limiting element is short-circuited is about 290 KV, so Vg ₀ −Vg = 200 KV, The operation start voltage Vb (120K
When V) is added, it becomes 320 KV. The flashover voltage 320 KV is the flashover voltage Vg ₀ (4
Since it is smaller than 90 KV), the condition of Vg ₀ ≧ Vb + Vg is satisfied. When this lightning insulator device is tested, it is highly probable that the flashover is 99% or more on the discharge gap G side from the voltage of 50% flashover probability of lightning impulse voltage to the experimentally high 10 times higher voltage region. It turned out that it occurs in.

On the contrary, in the conventional example, under the condition that Z / Z ₀ is 50% and the operation start voltage Vb of the current limiting element 20 is 130 KV, as a result of the experiment, flashover occurs in the discharge gap G, but Z / Z ₀ Is 50% and the operation start voltage Vb is 210
At the time of KV, a flashover occurred in the insulating gap G ₀ of the support insulator 7.

By the way, in the insulation design of the actual lightning arrester device,
The lightning impulse / flashover voltage Vg ₀ fluctuates due to electrode shape factors such as whether the tips of the arcing horns 12 and 13 are sharp or round. Therefore, a coefficient of 0.8 to 1.2 is added to the flashover voltage Vg _0. The lightning impulse flashover voltage Vg when the current limiting element is short-circuited is similarly multiplied by the coefficient Ka and the shape of the tips of the discharge electrodes 18 and 19 causes
Also varies by a coefficient Kc of 0.8 to 1.2. Further, the first turning which is a necessary level for the operation starting voltage Vb is also required depending on the characteristics of the current limiting element 20 and the energization cross section of the element. Although the area cannot be specified, it is usually 1 mA
The design is made by multiplying the control voltage VimA for flowing the current of (1) by a coefficient Kb of 0.8 to 1.2.

Further, the flashover probability has a statistical variation, and the insulation design is performed with Vg ₀ /Vt≧1.20 in consideration of safety.

The present invention can also be embodied as follows.

(1) Although the lightning protection insulator 15 is provided on the ground side in the above-described embodiment, it is provided on the power-supply side or at two locations on the ground side and the power-supply side, or discharge gaps are provided at a plurality of locations in series. Providing at least one lightning protection insulator 15 in series there.

(2) To be embodied in a tension insulator device (not shown) or a V suspension insulator device.

As described above in detail, even if a lightning surge voltage is applied to the transmission line, the present invention surely causes the surge current to flash over between the discharge gaps to prevent the flashover in the insulating gap on the supporting insulator side. It is possible to prevent this, the discharge gap length and the insulation gap length can be optimally set, and the pillar structure can be downsized.

[Brief description of drawings]

1 is a graph showing the relationship between the discharge gap length and the flashover voltage, FIG. 2 is a graph showing the relationship between the insulation gap length and the flashover voltage, and FIG. 3 is the discharge gap length and the flashover voltage. A graph showing the relationship with
FIG. 4 is a graph showing the relationship between the current of the current limiting element and its operation starting voltage, FIG. 5 is a front view showing the entire lightning arrester device for a transmission line, and FIG. 6 is a conventional lightning arrester device for a transmission line. It is a perspective view shown. 1 ... Tower, 2 ... Support arm, 7 ... Support insulator, 10
...... Transmission line, 12,13 ...... Arching horn, 15 ...
... lightning insulator, 18, 19 ...... discharge electrodes, 20 ...... current-limiting device, the discharge gap G ...... discharge electrodes 18 and 19, _{G 0} ...
... Insulation gap of arcing horns 12 and 13, Vg ...
... Flashover voltage at discharge gap G, Vg ₀ ...
Lightning impulse flashover voltage at the insulation gap G ₀ , Ib ... Current of current limiting element 20, Vt ... Current limiting element 2
Total lightning impulse flashover voltage between 0 and discharge gap G.

Claims (1)

[Claims] 1. A power transmission line is supported on a support arm of a steel tower via a support insulator, and discharge electrodes on a ground side and a charging side are arranged to face each other at a predetermined distance from the support insulator, and at least one of the two discharge electrodes. In the case where, for example, a current limiting element having zinc oxide as a main material and having a non-linear voltage-current characteristic is provided in series on the discharge electrode side, and further a lightning surge enters the transmission line to cause a flashover. In a lightning arrester device for an overhead power transmission line having a function of interrupting subsequent current, a lightning impulse flashover voltage in an aerial insulation gap of the support insulator is set to Vg _0, and an operation start voltage of the current limiting element is set to Vb, and the lightning impulse in the air discharge gap when the current limiting element is electrically short-circuited.
When the flashover voltage is Vg, the air insulation gap length of the support insulator, the air discharge gap length between the discharge electrodes, and the electrical characteristics of the current limiting element are set so that Vg ₀ > Vb + Vg. A characteristic lightning protection device for power transmission lines.