JPH0541121A - Lighting stroke energy suppressing structure in insulator apparatus supporting electric cable - Google Patents

Abstract

PURPOSE:To lower the possibility of occurrence of grounding accidents, that is flashover runs along the surface of a supporting insulator from an electric cable to a supporting arm even if lightning surge current rushes into the electric cable. CONSTITUTION:A supporting insulator 5 is connected with a supporting arm 2 of a steel tower through a connecting metal fitting 3 in the earthing side, an electric cable 8 is supported in the electricity applying side of the supporting insulator 5 through a connecting metal fitting 6, and a shunting wire 11 which electrically connects the front and the rare of the connecting metal fitting 6 in the electricity applying side is installed. Blocking coils 9, 10 are also installed wherein the coils lead lightning surge current to the shunting wire 11 in the case that the lightning surge current rushes into the electric cable 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses lightning energy that acts on the charging side of a support insulator of an electric wire when a lightning strike occurs in the electric wire support insulator device, and flashes over the surface of the support insulator from the electric wire to a steel tower. The present invention relates to a lightning strike energy suppression structure in an electric wire support insulator device which can reduce the probability of occurrence of a ground fault accident due to a lightning surge current flowing through the wire support insulator and can also reduce the size and weight of the lightning insulator when attached. is there.

[0002]

2. Description of the Related Art Generally, in an electric wire support insulator device for a tower that supports a transmission line, a support insulator composed of a suspension insulator string is provided on a support arm horizontally supported on a side portion of a tower body via an upper connecting fitting on the ground side. The power transmission line is supported on the lower end portion of the support insulator via a lower connecting metal fitting on the power-supply side and an electric wire clamp. Further, an overhead ground wire for supporting a communication function and for reducing a lightning surge current entering the tower is supported on the top of the tower main body.

Further, there are the following five types of modes in which a lightning surge current enters the electric wire support insulator device during a lightning stroke. (1) When entering the top of the tower main body after entering the middle of the overhead ground wire.

(2) When directly invading the top of the tower main body. (3) When entering the tip of the support arm. (4) When entering the lower connecting metal fitting on the power distribution side after entering the middle part of the power transmission line.

(5) In the case of directly intruding into the lower coupling fitting on the side of charging. Further, in recent years, in order to prevent a temporary power failure accident due to a continuous current after a lightning strike in a transmission line, a tower has a voltage with a condition for suppressing a continuous current based on an operating voltage following a lightning surge current. A lightning arrestor with a built-in resistance element whose current characteristic is non-linear is mounted. The lightning insulator supports a discharge electrode on the ground side which faces the discharge electrode supported on the lower connecting metal fitting on the power-supply side with a predetermined air discharge gap.

[0006]

In the above-mentioned electric wire support insulator device, (1)
In the case of the overhead ground wire invasion, the lightning surge current that halves by shunting into the upstream and downstream sides of the lightning strike point of the overhead ground wire enters the crown of the tower, and therefore passes through the tower itself. Since the current discharged to the ground is further attenuated, it is extremely unlikely to flash over the surface of the support insulator.Therefore, the probability of occurrence of a ground fault accident due to a continuous current based on the operating voltage following the lightning surge current Is very low and there is no problem.

Further, in the case of directly entering the top of the tower body in (2), the lightning surge current flowing in the tower increases as compared with (1), but in that case, the shunt surge current from the tower body to the support arm. Acts on the support insulator, the probability of an accident of flashing over the surface of the support insulator does not increase so much, and there is no particular problem.

However, in the case of (3) invading the tip of the supporting arm, the supporting insulator is mounted in the vicinity, so that the supporting insulator is closer to the transmission line side than the (2) intrusion form. The probability of a flashover and a ground fault will increase.

In addition, in the case of (4) when entering the lower connecting metal fitting on the power supply side after entering the middle portion of the power transmission line, the lightning point of the power transmission line is used as a boundary to divide the current into the upstream side and the downstream side. Since the lightning surge current that has halved due to the intrusion into the connecting metal fitting, the probability of occurrence of a ground fault that causes flashover from the support insulator to the support arm side increases as in the case of (3).

Furthermore, in the case of (5) intruding into the lower connecting metal fitting on the power-supply side directly or into a nearby power transmission line, most of the lightning surge current will be shunted to the supporting insulator portion.
The probability that a flashover will occur from the support insulator to the support arm side and a ground fault will occur will be further increased compared to the intrusion form of (4).

By the way, when the lightning protection insulator is applied to the electric wire support insulator device, the largest possible lightning surge current in the intrusion form of (5) among the intrusion forms of (1) to (5) described above is detected. It flows to the support arm of the steel tower through the medium discharge gap and the resistance element of the lightning arrester, and discharges to the ground, and it is possible to suppress the continuous current that occurs thereafter.
The capacitance of the resistance element is set. That is, it has been necessary to use a lightning arrester provided with a resistance element having a large radial dimension capable of withstanding the largest lightning surge current. In other words, it is necessary to use a lightning protection insulator which does not cause conduction breakdown of the resistance element even when the maximum expected lightning surge current flows. The length of the resistance element is set to a predetermined length according to the voltage class of the applied transmission line.

On the other hand, there is a difference in the intensity of lightning from one digit to two digits in lightning strikes. And because it is possible to design a practical resistance element dimension for light energy lightning,
The lightning protection insulator also does not become large, and there is no problem in manufacturing or application to the existing electric line. However, it is difficult to deal with large-energy lightning with practical dimensions even if the conventional design standard is adopted. Then, when a large amount of lightning strikes in the form of (5) near the connecting metal fittings of the support insulator on the side where the power is applied, the lightning surge current becomes the largest and it becomes very difficult to cope with it.

Of the above-mentioned intrusion forms, the present invention is (4)
It was proposed to deal with lightning with a large amount of energy when it enters the middle part of the electric wire of the electric wire, and the purpose is to attenuate the lightning surge current reaching the connecting metal fitting that connects the electric wire support insulator and the electric wire. However, it is possible to reduce the probability of occurrence of a ground fault that flows over the surface of the support insulator by flowing over to the support arm, and reduces the duty of the built-in resistance element against the lightning surge current when the lightning protection insulator is installed. Therefore, it is another object of the present invention to provide a lightning strike energy suppressing structure in an electric wire support insulator device which can reduce the size and weight of the lightning arrestor.

[0014]

In order to achieve the above object, the invention according to claim 1 connects a supporting insulator to a supporting arm of a steel tower via a grounding side connecting metal fitting, and connects the supporting insulator to the charging side of the supporting insulator. Is a wire support insulator device that supports the electric wire via a connecting metal fitting, with a shunt line that electrically connects the front and rear of the connecting metal fitting on the charging side, and if a lightning surge current enters the electric wire, the lightning surge current The method is to provide a surge inducing means for inducing the shunt line to the shunt line.

Further, the invention according to claim 2 is based on claim 1, wherein a means for interposing a blocking coil as a surge inducing means between the connection point between the electric wire and the shunt line and the coupling fitting on the power-supply side is provided. I am taking it.

The invention according to claim 3 is based on claim 1, wherein a capacitor serving as surge inducing means or a resistance element having a non-linear voltage-current characteristic is interposed in the shunt line.

Further, in order to achieve the above object, the invention according to claim 4 is the transmission line between the two connection points of the power transmission line and the shunt line, wherein the blocking coil is connected in series to the shunt line. Is covered with an insulating material.

[0018]

According to the invention described in claim 1, when the lightning surge current intrudes into the transmission line at the time of lightning,
The lightning surge current is induced in the shunt line by the surge inducing means, and the surge current to the side of the connecting metal fitting that connects the supporting insulator and the electric wire is attenuated. For this reason, the probability of occurrence of a ground fault that flows from the electric wire to the support arm by flashing over the surface of the support insulator is reduced.

Further, when the lightning protection insulator is attached to the electric wire support insulator device, the surge current flowing through the resistance element built in the lightning protection insulator is attenuated, so that the energy duty of the resistance element is reduced and the element size is reduced. And weight reduction can be achieved.

According to the second aspect of the invention, since the commercial frequency current has a low frequency, the impedance of the blocking coil is low and flows through this coil side. Since the frequency of the lightning surge current that has entered the middle portion of the electric wire is significantly higher than the frequency of the commercial current, the impedance of the blocking coil increases. Therefore, the probability of occurrence of the above-mentioned ground fault is reduced.

According to the third aspect of the invention, the capacitor or the resistance element has a high impedance with respect to the current of the commercial frequency, and the commercial current flows on the side of the electric wire. Then, since the impedance of the capacitor or the resistance element becomes low with respect to the lightning surge current having a high frequency, the lightning surge current flows in the shunt line, and the probability of occurrence of the above-mentioned ground fault is reduced.

Further, in the invention according to claim 4,
The impedance of the blocking coil is low with respect to the current of the commercial frequency and flows through this coil side. Since the impedance of the blocking coil increases with respect to the lightning surge current, the lightning surge current flows through the wire covered with the insulating material. Therefore, the probability of occurrence of the aforementioned ground fault is reduced.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment embodying the present invention will be described below with reference to FIGS. As shown in FIG. 2, the support arms 2 are laterally supported on the left and right sides of the tower main body 1 at three positions on one side for three-phase two-line, six positions in total. As shown in FIG. 1, a supporting insulator 5 having a plurality of suspension insulators 4 connected in series via a connecting metal fitting 3 on the ground side is suspended from these supporting arms 2. A power transmission line 8 is supported on the lower end of the support insulator 5 via a coupling metal fitting 6 on the charging side and an electric wire clamp 7.

A pair of front and rear blocking coils 9 and 10 as surge inducing means are connected in series to the power transmission line 8 so as to be located near the electric wire clamp 7. or,
A shunt line 11 for shunting a lightning surge current is supported on the outer sides of the both blocking coils 9 and 10, and both front and rear ends of the shunt line 11 are connected to the transmission line 8 by the coils 9 and 10.
It is electrically connected so as to sandwich 10.

On the other hand, a mounting adapter 21 is supported on the support arm 2 as shown in FIG. 1, and a lightning arrestor 22 is suspended and fixed to the adapter 21. This lightning protection insulator 22
Incorporates a resistance element 23 whose main component is zinc oxide having a non-linear voltage-current characteristic. Further, the resistance element 23 is housed in a pressure-proof insulating cylinder (not shown), and the metal fittings 24 and 25 on the ground side and the charging side are fitted to both ends of the insulating cylinder. An insulating jacket 26 made of rubber or the like is molded on the outer peripheral portion of the pressure-proof insulating cylinder. Further, the electrode fitting 25 supports a discharge electrode 28 on the ground side that faces the discharge electrode 27 on the charge side supported by the connecting fitting 6 on the charge side with a predetermined air discharge gap G.

Next, the operation of the transmission line lightning arrester device configured as described above will be described. Now, in FIG. 1, when a lightning surge current due to a lightning strike enters the power transmission line 8, this current is shunted to the upstream side and the downstream side with the lightning strike point as a boundary, and the shunt surge current is directed to the supporting insulator 5 side. Flowing. Then, the shunt surge current I / 2 flows in the direction of the arrow A in FIG. 1, and is shunted from the connection point P between the power transmission line 8 and the shunt line 11 to the blocking coil 10 and the shunt line 11. At this time, since the surge current which is about to flow in the blocking coil 10 is blocked by the coil, most of the surge current flows in the shunt line 11, so that the connecting metal fitting 6 of the support insulator 5 on the voltage application side has an extremely small surge current. Since only the electric current enters, it does not flow into the lightning arrestor 22 through the air discharge gap G.

Assuming that the impedance Z of the blocking coil 10 is f and the inductance of the coil 10 is L,

[0028]

## EQU1 ## Z = 2πfL ... 1 Therefore, commercial frequency (50 or 60 Hz)
Since the impedance Z of the coil 10 is small with respect to the current, the current flows through the blocking coil 10. Then, when the frequency is remarkably high as about 100 KHz like the lightning surge current compared to the commercial frequency, the impedance Z of the coil 10 becomes large according to the expression 1, and most of the shunt lightning surge current I / 2 is the shunt line. Because it flows through 11.
The surge current flowing to the connecting fitting 6 is attenuated. For this reason, the probability of occurrence of a ground fault that flows over the surface of the support insulator 5 from the electric wire 8 to the support arm 2 is reduced.

When a lightning surge current having a larger energy than the normal lightning surge current enters, the shunt surge current attenuated by the blocking coil 10 may flow to the lightning protection insulator 22. At this time, due to the split lightning surge current, the current flowing from the discharge electrode 27 on the charging side to the air discharge gap G to the discharge electrode 28 on the ground side is also reduced, and the current flows to the resistance element 23 built in the lightning protection insulator 22. The flowing lightning surge current is reduced, and the duty of the electric resistance processing of the resistance element 23 is reduced accordingly. As a result, it is not necessary to design the resistance element 23 in consideration of the case where a large amount of lightning energy penetrates into the metal fitting 6, and the energization cross-sectional area of the resistance element 23 is reduced to reduce the size and weight of the element. It is possible to easily manufacture the lightning protection insulator and reduce the cost of the lightning protection insulator.

Although the shunt line 11 is arranged outside the power transmission line 8 in the above-described embodiment, in this case, the side of the steel tower is directed toward the connecting fitting 6 located at the lower end of the support insulator 5 which is extremely rare. It is possible to reliably capture the surge current flying from the terminal before entering the connecting fitting 6. In this case, the lightning strike point becomes the midpoint of the flow dividing line 11, but in this case as well, the surge current flowing to the coupling fitting 6 side is attenuated by the blocking coil 10, and most of it is upstream and downstream of the power transmission line 8. Shunt to the side.

Further, since the lightning surge current entering the connecting metal fitting 6 side is attenuated, the ground fault reaching the support arm 2 by flashing over the creeping surface of the support insulator 5 when the lightning protection insulator 22 is not mounted. The probability of accidents is reduced.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the electric wire clamp 7 is connected to the shunt line 1
1 is supported by an insulating support rod 12, and the flow dividing line 1
Two capacitors 1 as surge induction means for 1
3, 14 are connected in series. This capacitor 13,
Instead of 14, a resistance element similar to the resistance element 23 may be used.

In the second embodiment, the impedance Z of the capacitors 13 and 14 at a normal commercial frequency current is used.
Let C be the capacitance of the capacitor,

[0034]

## EQU2 ## Z = 1 / 2.pi.fC .. Therefore, it is difficult for the commercial current having a low frequency to pass through the capacitors 13 and 14, so that the current flowing to the shunt line 11 is very small, and most of the commercial current flows to the power transmission line 8.

With respect to a lightning surge current having a high frequency due to a lightning stroke, the impedance Z of the capacitors 13 and 14 becomes small according to the above equation 2, so that the shunt line 11 is connected from the connection point P.
To the power transmission line 8 again through the capacitors 13 and 14. Therefore, the lightning surge current flowing to the connecting metal fitting 6 side on the power supply side is greatly attenuated, and the same action and effect as those of the first embodiment described above are exhibited.

Furthermore, the third aspect of the present invention will be described with reference to FIG.
An example will be described. In the third embodiment, the power transmission line 8 having a predetermined length before and after the coupling fitting 6 of the power transmission line 8 is covered with the insulating coating 15, and the power transmission line 8 at both ends of the insulating coating 15 is covered with the above-mentioned blocking coil 9. It is electrically connected by 10.

In this embodiment, the commercial frequency current flows through both the blocking coils 9 and 10 and the transmission line 8, and the high frequency lightning surge current flows into the blocking coils 9 and 1.
Since the impedance Z of 0 becomes large, the insulation coating 15
Flows through the power transmission line 8 inside. Therefore, the lightning surge current flowing through the connecting fitting 6 is attenuated, and the same action and effect as those of the first embodiment are obtained.

The present invention is not limited to the above embodiment, but may be embodied as follows. (1) To constitute an electric wire support insulator device in which the support insulator 5 itself has a lightning protection function.

(2) As the insulating support bar 12, an outer cover of FRP (fiber reinforced synthetic resin) having a fold, such as EPDM or silicon rubber, is provided. (3) Applicable to tension-type wire support insulator devices other than suspension-type wire support insulator devices.

[0040]

As described in detail above, according to the present invention, even when a lightning surge current enters a power transmission line, the lightning surge current is shunted to attenuate the lightning surge current reaching the voltage applying side of the supporting insulator. However, it is possible to reduce the probability of occurrence of a ground fault accident that flows over the surface of the support insulator from the wire to the support arm, and when the lightning protection insulator is installed, it is necessary to take responsibility for the lightning surge current of the built-in resistance element. It is possible to reduce the size of the lightning protection insulator and reduce the size and weight of the lightning protection insulator.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment embodying a lightning strike energy suppressing structure in an electric wire support insulator device of the present invention.

FIG. 2 is a front view showing the entire electric wire support insulator device.

FIG. 3 is a perspective view of an electric wire support insulator device showing a second embodiment of the present invention.

FIG. 4 is a perspective view of an electric wire support insulator device showing a third embodiment of the present invention.

[Explanation of symbols]

1 steel tower body, 2 support arms, 3 grounding side connecting metal fittings, 5 supporting insulators, 6 power distribution side connecting metal fittings, 8 power transmission lines,
9, 10 Blocking coil as surge inducing means, 11 shunt line, 13, 14 Capacitor as surge inducing means, 15 Insulation coating.

Claims (4)

[Claims] 1. An electric wire support insulator device in which a support insulator is connected to a support arm of a steel tower via a grounding side connecting metal fitting, and an electric power supporting side of the supporting insulator supports an electric wire via the connecting metal fitting. An electric wire characterized by being provided with a shunt line for electrically connecting the front and rear of the connecting side metal fitting, and provided with a surge inducing means for guiding the lightning surge current to the shunt line when a lightning surge current enters the electric wire. Stroke energy suppression structure in supporting insulator device. 2. The lightning strike energy suppressing structure for an electric wire support insulator device according to claim 1, wherein the surge inducing means is a blocking coil interposed between a connection point between the electric wire and the distribution line and a connecting metal fitting. .. 3. The lightning strike energy suppressing structure according to claim 1, wherein the surge inducing means is a capacitor interposed in a shunt or a resistance element having a non-linear voltage-current characteristic. 4. The lightning strike energy suppression in an electric wire support insulator device according to claim 1, wherein a blocking coil is connected in series to the shunt line, and the transmission line between two connection points of the transmission line and the shunt line is covered with an insulator. Construction.