JPH0319647B2 - - Google Patents

Description

[Detailed description of the invention]

Object of the Invention (Field of Industrial Application) The present invention relates to a lightning insulator device for overhead power transmission lines. (Prior Art) Conventionally, a lightning insulator device has been proposed that promptly discharges lightning surge voltage when it is applied to a power transmission line, and blocks the subsequent follow-on current to prevent ground faults. As this lightning insulator device, the power transmission line is supported on the support arm of the steel tower via the support insulator, and the lightning arrester is suspended and fixed, and the discharge electrode attached to the lower end of the lightning arrester is attached to the power transmission line side. In addition, the power transmission line is supported via a support insulator on the support arm of the steel tower, and a lightning arrester with a built-in nonlinear resistance element is suspended and fixed to the support arm of the steel tower. There is a method in which the power transmission line is connected to the lower end of the lightning arrester. (Problem to be Solved by the Invention) In the former lightning insulator device, when lightning surge voltage is applied to the power transmission line, the abnormally high voltage flows through the discharge gap provided at the lower end of the lightning arrester and is discharged into the lightning arrester. It is discharged through a non-linear resistance element. When dealing with anticipated lightning surges, it is important to not only prevent flash faults from occurring in the gap between the pair of arcing horns attached to the upper and lower ends of the lightning arrester, but also to prevent flash faults from occurring even if the lightning strikes exceed expectations. In order to prevent secondary damage between the horns, the insulation clearance between the arcing horn on the supporting insulator energized side and the steel tower must be absolutely free from flash faults. On the other hand, in the latter lightning protection insulator device, an abnormally high voltage is discharged through the nonlinear resistance element of the lightning protection insulator. In the event of a lightning strike that exceeded expectations, a similar response would have been required. In order to apply these lightning insulators to power transmission lines, improve the reliability of the lightning insulators in handling lightning surges, and downsize towers through rational design, the arcing horn gap length and insulation clearance must be adjusted. It was necessary to set the dimensional ratio between them to an optimal relationship. Structure of the Invention (Means for Solving the Problems) In order to solve the above-mentioned problems, the first invention supports a power transmission line via a support insulator on a support arm of a steel tower, and suspends and fixes a lightning arrester insulator, A predetermined discharge gap length G2 is provided between the discharge electrode attached to the lower end of the lightning arrester and the discharge electrode attached to the power transmission line side, and a pair of arcing electrodes attached to both the upper and lower ends of the lightning arrester are provided. Between the gap length G3 of the horns, the gap length G1 between the pair of arcing horns attached to both ends of the support insulator, and the insulation clearance C between the arcing horns attached to the lower ends of the support insulator and the steel tower. Then, before discharge in discharge gap G2, G1, C≧G2×(1.18 to 2.0) During discharge = After discharge in G2, C≧G3×(1.08 to 1.53) G1≧G3 Gap length G1 to The method is to set G3 and insulation clearance C. In order to solve the above-mentioned problems, the second invention supports a power transmission line via a support insulator on a support arm of a steel tower, and also suspends and fixes a lightning arrester insulator with a built-in non-linear resistance element at the lower end of the lightning arrester. A transmission line is connected to the support insulator, the gap length of the arcing horns attached to both ends of the support insulator is set as G1, the gap length of the pair of arcing horns disposed opposite to each other at both the upper and lower ends of the lightning arrester is set as G3, and the gap length of the arcing horns is set as G3. If the insulation clearance between the arcing horn attached to the lower end of the insulator and the steel tower is C, then the gap lengths G1 and G3 and the insulation clearance C are set so that C≧G3×(1.08~1.53) G1≧G3. I am using the method of setting. (Function) In the first invention, when a lightning surge is applied to a power transmission line or a steel tower, a voltage is applied between gaps G1 and G3 and the insulation clearance C between the power transmission line and the steel tower until a discharge occurs in the discharge gap G2. However, when the lightning surge exceeds the discharge starting voltage of the discharge gap G2, this portion is discharged and is discharged to the support arm via the nonlinear resistance element of the lightning arrester, suppressing the lightning surge voltage. No flashover occurs in the gaps G1, G3 and the insulation clearance C. Furthermore, even if the lightning strike exceeds expectations, flash shorting will not occur in areas other than the arcing horn gap G3 of the lightning arrester because the insulation gap is provided between each gap and the insulation clearance. The second invention is that when a lightning surge is applied to a power transmission line, a voltage is applied between the gap G3 and the insulation clearance C between the power transmission line and the steel tower until discharge occurs in the nonlinear resistance element built into the lightning arrester. However, when the lightning surge exceeds the discharge starting voltage of the nonlinear resistance element, discharge begins in the nonlinear resistance element and the lightning surge voltage is suppressed, so a flashover occurs between the gap G3 and the insulation clearance C. will not occur. In addition, even if the limiting voltage of the non-linear resistance element increases due to a lightning strike that exceeds expectations, a flashover will occur in the insulation clearance C because there is an insulation difference between the gap G3 and the insulation clearance C. Never. (Example) Hereinafter, a first example embodying the first invention will be described as a first example.
This will be explained based on the diagram and FIG. At the middle part of the support arm 2 attached to the steel tower 1, there is an upper cap metal fitting 4 of a support insulator 3 made of a long insulator.
is fixed with bolts, and a power transmission line 7 is supported via a gripping fitting 6 on a lower cap fitting 5 which is fitted and fixed to the lower end of the support insulator 3. Arcing horns 8 and 9 are disposed on both the upper and lower cap fittings 4 and 5 to face each other with a predetermined gap G1 in order to prevent damage to the supporting insulator 3 due to creeping flash. An arcing horn 10 serving as a discharge electrode on the power supply side is supported on the gripping metal fitting 6. On the other hand, an upper electrode fitting 13 of a lightning arrester 12 having a built-in resistance element 11 having non-linear voltage-current characteristics (hereinafter simply referred to as a non-linear resistance element) is fixed to the tip of the support arm 2 with a bolt. An arcing horn 15 serving as a discharge electrode is supported on the lower electrode fitting 14 of the lightning arrester 12 so as to face the arcing horn 10 with a predetermined discharge gap G2 and to be adjustable in position in the horizontal direction. Both upper and lower electrode fittings 13, 1 of the same lightning arrester 12
4 is an arcing horn 16, 1 for preventing damage to the lightning arrester 12 during creeping flash or pressure release.
7 are arranged facing each other with a predetermined gap G3. A predetermined insulation clearance C is provided between the arcing horn 9 and the steel tower 1 to prevent discharge from occurring from the arcing horn 9 to the steel tower 1 when a lightning surge is applied. First, consider the insulation design from when a lightning surge is applied until the discharge gap G2 is discharged. In this type of equipment, the insulation strength of the discharge gap G2 is set to withstand the switching surge voltage so that even if the nonlinear resistance element becomes conductive due to a lightning strike that exceeds expectations, forced power transmission can be performed by reinsertion. be done. By setting the dimensional ratio of the gaps G1, G3 and the insulation clearance C to the discharge gap G2 to an appropriate value, it becomes possible to reliably discharge lightning surges in the discharge gap G2. In this embodiment, the dimensional ratios of these gaps G1 to G3 and the insulation clearance C are set as follows. As the discharge starting voltage for the preset discharge gap G2, take the average value V50 plus 2σ to 3σ, and for gaps G1, G3 and insulation clearance C, subtract 2σ to 3σ from the average value of the flash voltage in those areas. The dielectric strength ratio of the two was set so that the two values differed from each other by the same value. In addition, as a result of testing, it was found that the variation in flash fault voltage due to lightning surge between G1, G2, G3 and insulation clearance C was determined by the shape of the arcing horn, the relative position with respect to the tower 1, weather conditions, or the arcing horn 9. Although it depends on the diameter of the material and the configuration of the insulation clearance C, a standard deviation σ of 2 to 7% is considered. That is, the discharge starting voltage of G2 between insulations is set to V,
The flash voltage between G1, G3 and the insulation clearance C is set as V0, and in order to ensure that they are separated from each other by the same value even under the worst conditions considering variations, the following equation is satisfied. (When the variation is 2σ) V0×(1-2σ)/V×(1+2σ)≧1∴V0≧V× (1+2σ/1-2σ) (When the variation is 3σ) V0×(1-3σ)/V ×(1+3σ)≧1∴V0≧V× (1+3σ/1-3σ) Here, (1+2σ)/(1-2σ) or (1
+3σ)/(1-3σ) is the insulation strength ratio (K),
The ratio can be determined as shown in Table-1.

[Table] In addition, the flash fault voltage of G2 during discharge is
If they are connected in series, the increase will be 10 to 30% compared to when they are not connected, so this must be taken into consideration when setting the dimension ratio based on the discharge interval = G2. Also, when comparing the distance length, the distance length and flash voltage are almost proportional, so the ratio is (1.08~1.13) x (1.10~1.30)~(1.33~
1.53)×(1.10~1.30), that is, (1.46~2.0). Therefore, before the discharge during the discharge period G2, it is possible to reliably discharge the lightning surge during the discharge period G2 by setting the relationship between each period G1 to G3 and the insulation clearance C as follows. Become. G1, C≧G2×(1.18 to 2.0) On the other hand, in the operating state where G2 is discharged and lightning surge current flows through the nonlinear resistance element 12 of the lightning arrester 12, as shown in FIG. The lightning surge voltage applied to the nonlinear resistance element 11 becomes a nearly constant value, and at this time, as shown in Table 1, with the gap G3 side as a reference, the flash voltage average value V50 on the gap G3 side has a standard deviation. The sum of 2σ to 3σ, and the value of that part on the gap G1 and insulation clearance C side.
It is sufficient to compare the value obtained by subtracting 2σ to 3σ from V50 and set the dimensional ratio of the gap G1 and the insulation clearance C so that the two are separated by the same value. Therefore, after the discharge of the discharge interval G2, if the relationship between the respective intervals G1, G3 and the insulation clearance C is set as shown in the following formula, the lightning protection insulator will remain intact even if it receives a lightning strike that exceeds expectations. 12 arcing horns 16 and 17 generate a flash at G3,
Since flash faults are not generated between the gap G1 and the insulation clearance C, safety can be improved by eliminating melting of electric wires or damage to steel towers due to arcs. C≧G3×(1.08 to 1.53) G1≧G3 Below, the dimensions of each gap G1 to G3 and the insulation clearance C will be illustrated with specific numerical values. In FIG. 1, the discharge gap G2 is set to, for example, 500 mm based on the above-mentioned concept of withstanding switching surge voltage. First, before discharge occurs in the discharge gap G2, the insulation strength ratio is set to 1.18 to 2.0 compared to the discharge gap G2, so the gap length is approximately 590 to 1000 mm. With this relationship, the gap G1,
This means that no flashover occurs at G3 or insulation clearance C in the first place. Next, when the discharge gap G2 is discharged and a lightning surge current flows through the nonlinear resistance element inside the lightning arrester, and a limiting voltage due to the surge is generated in the arcing horn gap G3 at both ends, the gap length G3 between both arcing horns is For example, 750mm to withstand this voltage.
It is set as follows. In this state, the gap G
1 and the insulation strength of the insulation clearance C is set to 1.08 to 1.53 compared to the gap G3, so the gap length is approximately 810 to 1150 mm. however,
In cases where a design with tighter clearance is required, the arcing horns 8 and 9 of the support insulator 3 and the tensile support insulator 21 are designed to have improved arc resistance, so that in the unlikely event that a flash short occurs between the arcing horns and a follow-up current occurs. In some cases, a design is adopted in which there is no damage to the insulator or damage due to arc migration to the steel tower even if arc flows. In such a case, G1≧G3 may be satisfied. Next, the operation of the lightning insulator device for overhead power transmission lines constructed as described above will be explained. Now, when a lightning surge is applied to the power transmission line 7, the surge voltage at this time increases with the passage of time as shown in the graph of Fig. When the current is exceeded, a discharge occurs, and a surge current is discharged to the support arm 2 via the nonlinear resistance element 11. During this time, the voltage across the lightning arrester is maintained approximately constant. When the discharge ends, the lightning surge voltage decreases as shown in FIG. Subsequently, a commercial frequency current attempts to flow, but is limited by the nonlinear resistance element 11 and the discharge gap G2, and subsequent current is blocked. Now, in the embodiment of the first invention, each gap G1 to G3
and the dimensional ratio of the insulation clearance C is the discharge gap G2
Before the discharge of G1, C≧G2×(1.18 to 2.0) During discharge = After the discharge of G2, C≧G3×(1.08 to 1.53) G1≧G3 is set so that the lightning surge can be reliably prevented. The reliability of the lightning surge treatment can be further improved and the steel tower can be designed rationally by causing a discharge to occur in the discharge gap G2 and preventing flash shorting in the gap G1 and the insulation clearance C even if a lightning strike exceeds expectations. Next, the second embodiment embodying the second invention will be described in a third embodiment.
This will be explained based on the diagram and FIG. This second embodiment has a pair of left and right tensile support insulators 21.
The jumper wire 22 that connects the power transmission line 7 is held at the lower end of the lightning arrester 12 at approximately the center thereof. Further, a pair of arcing horns 16 and 17 attached to both upper and lower ends of the lightning arrester 12 are opposed to each other with a predetermined gap G3. In addition, the insulation clearance C between the lower arcing horn 17 and the steel tower 1, and the gap G
1 and G3, the same relationship is maintained for the reason stated in the first embodiment. That is, the gaps G1 and G3 and the clearance C are set so that C≧G3×(1.08 to 1.53) G1≧G3. The concept of setting the condition of G1≧G3 is the same as that described in the first invention. Also in this second embodiment, the gaps G1 and G3 and the insulation clearance C are set to the minimum necessary,
Installation space can be reduced. Note that the present invention can also be embodied as follows. (1) Implementation in a device in which the positions of the lightning arrester 12 and the support insulator 3 are swapped in the first embodiment. (2) In the first embodiment, the present invention is applied to a device using the tensile support insulator 21 described in the second embodiment. Effects of the Invention As detailed above, the first invention prevents lightning surges by reliably discharging electricity in the discharge gap between the power transmission line and the lightning arrester even if a power transmission line or tower is struck by lightning and a lightning surge voltage is applied. It is possible to prevent flash shorts from occurring between the arcing horn of the lightning arrester supporting the power transmission line and the tower, that is, between the power supply side and the tower body, and furthermore, it is possible to prevent flash shorts from occurring between the arcing horn of the lightning arrester insulator supporting the power transmission line and the tower body. This not only improves safety by eliminating wire melting or damage to steel towers due to arcing, but also reduces the variation and standard deviation of flash voltage due to lightning surges by adjusting the discharge interval and insulation clearance. By taking this into consideration and setting it optimally, the pillar structure can be downsized. In addition, in the second invention, the same effects as those of the first invention described above can be expected when dealing with lightning surge voltage and receiving a lightning strike that exceeds expectations.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an embodiment embodying the first invention of the present invention, Fig. 2 is a graph showing voltage due to lightning surge, and Figs. 3 and 4 are an embodiment embodying the second invention. Two embodiments are shown; Fig. 3 is a front view, and Fig. 4 is a front view.
The figure is a sectional view taken along the line A--A in FIG. 3. 1... Steel tower, 2... Support arm, 3... Support insulator, 4, 5... Cap metal fitting, 6... Gripping metal fitting,
7...Power line, 8,9...Arching horn, 1
0, 15... Arcing horn as a discharge electrode, 11... Nonlinear resistance element, 12... Lightning arrester, 13, 14... Electrode fitting, 16, 17... Arcing horn, G1... Arcing horn 8,
9 gap, G2...arching horn 10, 15
The discharge gap between G3... arcing horn 16,
Gap between 17 and C... Insulation clearance between arcing horn 9 and steel tower 1.

Claims (1)

[Scope of Claims] 1. A power transmission line is supported on a support arm of a steel tower through a support insulator, and a lightning arrester is suspended and fixed, and a discharge electrode attached to the lower end of the lightning arrester is connected to the power transmission line side. The specified discharge distance between the attached discharge electrode
A length G2 is provided between a pair of arcing horns attached to both upper and lower ends of the lightning arrester; a length G3 is provided between a pair of arcing horns attached to both ends of the support insulator; a length G1 is provided between the pair of arcing horns attached to both ends of the support insulator; Between the insulation clearance C between the arcing horn attached to the lower end of the steel tower and the steel tower, during discharge = before discharge of G2, G1, C ≥ G2 × (1.18 to 2.0) during discharge = after discharge of G2 A lightning insulator device for an overhead power transmission line, characterized in that the distances G1 to G3 and the insulation clearance C are set so that C≧G3×(1.08 to 1.53) and G1≧G3. 2. A power transmission line is supported on the support arm of the steel tower via a support insulator, and a lightning arrester with a built-in non-linear resistance element is suspended and fixed, the power transmission line is connected to the lower end of the lightning arrester, and the power transmission line is connected to the support insulator. The length between the arcing horns attached to both ends of the lightning arrester is G1, and the length between the pair of arcing horns disposed opposite to each other at both the upper and lower ends of the lightning arrester is G3, and the length is G3, which is attached to the lower end of the lightning arrester. If the insulation clearance between the arcing horn and the steel tower is C, then the distances G1 and G3 and the insulation clearance C are set so that C≧G3×(1.08 to 1.53) and G1≧G3. Lightning insulator device for power transmission lines.