JP2951046B2 - Lightning arrester with air discharge gap - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention discharges a lightning surge current to the ground when a lightning strike occurs in a transmission line, and transmits a subsequent current corresponding to an operation voltage generated thereafter to the insulation strength of an air discharge gap and BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightning arrester having an air discharge gap capable of preventing a ground fault by suppressing and interrupting by restoring the resistance value of a nonlinear resistance element.

[0002]

2. Description of the Related Art In general, in an electric wire supporting insulator device for a tower supporting a transmission line, a supporting insulator consisting of a suspension insulator series is connected to a supporting arm horizontally supported on a side portion of a tower main body via an upper connecting metal fitting on a ground side. A power transmission line is supported at the lower end of the support insulator via a lower connection fitting on the power application side and a wire clamp. A surge arrester with a built-in resistance element with non-linear voltage-current characteristics with conditions for limiting the continuation current based on the operating voltage following the lightning surge current is installed on the support arm of the tower. ing. The lightning arrester supports a discharge electrode on the ground side, which is opposed to a discharge electrode supported by the lower connection fitting on the power application side with a predetermined air discharge gap.

[0003]

In the above-mentioned lightning arrester insulator device, the electrical characteristics such as the gap length of the air discharge gap and the operation starting voltage of the resistance element of the lightning arrester are determined according to the voltage class to be applied as follows. It is set as follows. The gap length of the aerial discharge gap should be ensured so that it does not flash over due to abnormal rising voltage under operating conditions or switching surge voltage generated by opening and closing of the circuit breaker. It is designed to flash over and protect the juxtaposed insulator devices from lightning surges.

The electrical characteristics of the resistive element are such that the following current can be cut off with a peak value of 1 to 2 so that the current can be suppressed and cut off by restoring the insulation characteristic of the air discharge gap and the resistance value of the resistive element.
The operation start voltage V _nA of the resistance element in the A current range is set to a voltage equal to or higher than the sound phase rise voltage V _{S at the} time of one-line ground fault. In other words, this indicates that the maximum value of the operating voltage at the time of processing the lightning surge is considered as the healthy phase rising voltage V _S. The current values of 1 to 2 A are experimentally obtained. That is, when the air discharge gap length set to withstand the assumed switching surge voltage and the resistance element are combined, the upper limit value of the current flowing through the resistance element that can surely block the continuation flow. If the current value is exceeded, the situation of the following flow interruption increases instability, and finally the following flow cannot be interrupted.

More specifically, from the viewpoint of the cutoff characteristic of the shunt current following the lightning surge current, the maximum voltage applied when the lightning arrester processes the lightning surge, that is, the normal operating voltage V _o with respect to the ground of the electric line, is determined. Assuming that the healthy phase rise voltage at the time of one-line ground fault that becomes K times is V _S , the operation start voltage V _{nA of the} resistance element
Is

[0006]

V _nA ≧ V _S (where: V _S = K × V _O ) Here, K is √3 for a general line of 22 to 154 kV which is a resistance reactor grounding system, and 1.3 is used for a general line of 187 kV or higher which is a linear grounding system. More specifically, Table 1 shows the nominal voltage of the line, the maximum line voltage, the ground voltage V _o , and the healthy phase rise voltage V _S.

[0007]

[Table 1]

In the lightning arrester device set as described above, the operation start voltage V _nmA in a current range of 1 to 2 mA, which is strongly related to the application life characteristic, is _changed with _respect to the ground voltage V ₀ to the voltage-current characteristic of the resistance element. As shown in FIG.
_nmA <V ₀ or V _nmA as in Conventional Example 2.
> V ₀ is conceivable. In the case of the former design, under normal operating conditions, a bird or the like intervenes between the discharge electrodes on the ground side and the power application side by shorting both discharge electrodes with a wire or conductive tape interposed between them. In this case, since the operation start voltage V _nmA <V _O of the resistance element is set as described above, the power application rate ε of the resistance element part due to the ground voltage V _o , that is, the applied voltage V _oMAX = √2 × V _O The value obtained by dividing by the operation start voltage V _nmA in the current range of 1 to 2 mA (ε = V
_OMAX / V _nmA ) exceeds 100%.

When such a situation occurs, the operating voltage V _o
As a result, the leakage current increases, and the resistance element may thermally break down. Such a situation is not a characteristic related to the original function of the lightning arrester insulator device, but it is a matter to be prevented because it is a situation that is sufficiently predicted in application. Next, in the latter design, the problem of the former design does not occur, but the number of resistive elements increases, so that the combination with the air discharge gap, that is, the lightning impulse flashover voltage as a lightning arrester insulator device is reduced. This caused a situation in which the coordination characteristics of insulation with the juxtaposed insulator device were reduced.

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above-mentioned problem, and an object of the present invention is to operate a resistance element in a lightning arrester in an abnormal condition such as when an air discharge gap is short-circuited by a wire or the like. It is possible to prevent breakdown due to voltage breakdown, and to reduce lightning impulse flashover voltage, and to improve insulation coordination characteristics for parallel insulator devices. It is an object of the present invention to provide a lightning arrester having a discharge gap.

[0011]

According to the present invention, in order to achieve the above object, a lightning arrester having a built-in resistive element having a non-linear voltage-current characteristic is mounted on a transmission line, and the lightning arrester is connected to a power receiving side of the lightning arrester. In the lightning arrester device provided with an air discharge gap between the lightning arrester and the transmission line, the characteristics of the resistance element of the lightning arrester are determined based on the cutoff characteristics of the shunt current following the lightning surge current.
Assuming that the operation start voltage in the current range of ~ 2A is V _nA and the healthy phase rise voltage at the time of one line ground fault of the transmission line is V _S ,

[0012]

## EQU4 ## In addition to setting V _nA ≧ V _S , the operation start voltage in the current range of 1 to 2 mA is V _nmA and the ground voltage in the normal state of the line is V _{0 in} view of the application life of the resistance element. Then

[0013]

## _EQU5 ## The means is set so that the relationship of V _nmA ≒ V ₀ is established.

[0014]

According to the present invention, the operation start voltage V _nA of the resistance element in the current range of 1 to 2 A is set to be equal to or higher than the sound phase rise voltage V _S at the time of a single-line ground fault, so that it will flow following the lightning surge current. Can be reliably shut off. Also, 1
By setting the operation start voltage V _{nmA in} the 2 mA current range to be equal to the value of the ground voltage V _o , even if the air discharge gap is short-circuited by a wire or the like, the leakage current abnormally increases and the resistance element is destroyed. It will not be done.

Further, the operation start voltage V _nmA in the current range of 1 to 2 _mA is closely related to the flashover voltage for the lightning impulse. In other words, the lightning impulse flashover voltage as the lightning arrester device is expressed as the sum of the flashover voltage of the air discharge gap alone and the effect of the resistance element. Here, if the influence is called a bias voltage, it is clear that the bias voltage is experimentally substantially equal to the operation start voltage V _nmA .
From this, a lightning arrester in which the operation start voltage V _nmA is set higher _{than the} ground voltage V _o is compared with a lightning arrester using a small resistive element which is set equal to a practically lower limit as in the present invention. Then, in the present invention, the lightning impulse flashover voltage is reduced, and therefore, the insulation coordination characteristics with respect to the insulator devices arranged side by side even with devices having the same length of the air discharge gap length are improved.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 2, a supporting insulator 4 formed by connecting a plurality of hanging insulators 3 in series is suspended from a supporting arm 1 of the tower via a connecting metal fitting 2 on the ground side.
A power transmission line 7 is supported at a lower end of the support insulator 4 via a connection metal fitting 5 and a wire clamp 6 on the power application side.

On the other hand, a mounting adapter 8 is supported on the support arm 1, and a lightning arrester 9 is suspended and fixed to the adapter 8. This lightning arrester 9 incorporates a resistance element 10 mainly composed of zinc oxide having a non-linear voltage-current characteristic. The resistance element 10 is accommodated in a pressure-resistant insulating cylinder (not shown), and ground-side and power-receiving-side electrode fittings 11 and 12 are fitted to both ends of the insulating cylinder. An insulation jacket 13 such as rubber is molded around the outer periphery of the pressure-resistant insulation cylinder. Further, the grounding-side discharge electrode 1 opposed to the power-supplying-side discharge electrode 14 supported by the power-supplying-side connection fitting 5 with a predetermined air discharge gap G is provided on the power-receiving-side electrode fitting 12.
5 are supported.

The connecting fittings 2 and 5 and the electrode fitting 1
Arc horns 16 for reducing damage at the time of a creepage flashover of the suspension insulator string 4 and the lightning arrester insulator 9 are provided at 1 and 12.
~ 19 are supported. Next, a method for setting the electrical characteristics of the resistance element 10 will be described with reference to FIG. From the cut-off characteristics of the follow current current following the operation start voltage V _nA lightning surge current in 1A~2A current region of the resistance element 10 of the lightning insulator 9, and the sound phase voltage rise of the line ground fault occurs in the line V _S Then

[0019]

## _EQU6 ## The characteristics of the resistance element 10 are set so that V _nA ≧ V _S. Here, V _nA can be set to a value as close as possible to V _S.
It is necessary to reduce the voltage limit when conducting lightning surge current and shorten the air insulation length of the lightning arrester or the air insulation length between the power-applied side of the lightning arrester and the grounding side of the parallel-arranged insulator device and the tower. is there. Here, the limiting voltage is a voltage drop caused by the resistance of the resistance element portion as shown by Ohm's law when the lightning surge current flows through the lightning arrester.

In order to prevent the resistive element 10 from being destroyed even in an abnormal use situation where the air discharge gap G is short-circuited by a wire or the like, from the viewpoint of the application life of the resistive element 10, an operation start voltage V _NMA in 1~2mA current region of the element 10 relative to the ground voltage V _o of the line,

[0021]

## _EQU7 ## The characteristics of the resistance element 10 are set so that the relationship of V _nmA ≒ V _o is established. The two operation start voltages V _nA and V _nmA
Are lower limits in design that allow for variations in manufacturing in order to continue to exhibit functions over a long period of time and a reduction due to surge deterioration caused by repeated lightning surge treatment during use. Therefore, the value in the initial stage of manufacturing is naturally designed to be larger than this value. This value is generally within 5-20%.

The above 1 mA _and 1 A in the 1-2 mA current range and 1-2 A current range are values corresponding to a resistance element having a diameter of about 46 mm (cross-sectional area of 16.61 cm ² ) widely used for lightning arresters. , 2 mA _and 2 A are values corresponding to an element having a diameter of about 65 mm (33.17 cm ² ) whose cross-sectional area is almost doubled. That is, the idea is that the current density is substantially the same even when the element diameter changes. The current density is approximately 0.060 (mA / cm ² ) in the mA range and 0.060 in the A range.
(A / cm ² ).

Next, the operation of the lightning arrester for a transmission line configured as described above will be described. Now, in FIG. 2, when a lightning surge current due to a lightning strike enters the power transmission line 7, it flashes over the aerial discharge gap G from the discharge electrode 14 on the power application side to flow to the discharge electrode 15 on the ground side. Flows through the resistance element 10 and is discharged to the ground via the electrode fitting 11, the mounting adapter 8, and the supporting arm 1 of the steel tower. Further, the subsequent current based on the operating voltage generated thereafter is suppressed and cut off by current limiting by restoring the air discharge gap G and the resistance value of the resistance element 10, thereby preventing a ground fault accident.

In the embodiment of the present invention, the characteristics of the resistance element are set in the most preferable form in relation to the following characteristics, namely, the following characteristics, that is, the following characteristics, that is, the following characteristics, that is, the follow-up cutoff characteristics, the service life, and the insulation coordination characteristics. As described above, when the operation start voltage of the resistance element 10 of the lightning arrester 9 in the current range of 1 to 2 A is V _nA , and the healthy phase rise voltage at the time of one line ground fault is V _S ,

[0025]

## _EQU8 ## Since the characteristics of the resistance element 10 are set so as to satisfy V _nA ≧ V _S , the following flow is reliably cut off. Further, when the discharge electrodes 15 and 14 on the ground side and the power supply side are short-circuited by a wire or the like, the grounding of the transmission line 7 is maintained only by the lightning arrester 9, but in this embodiment, the resistance element is used. 10 between the operation start voltage V _{nmA in} the 1 to 2 mA current range and the ground voltage V _{o of the} line at a power _application rate of about 100%,

[0026]

## _EQU9 ## Since the characteristics of the resistance element 10 are set so that the relationship of V _nmA ≒ V _O is satisfied, the following effects are obtained. That is, even when the air discharge gap G is short-circuited by a wire or the like, the leakage current does not abnormally increase and the resistance element 10 is not destroyed.

According to experiments, when the period until the abnormal state is removed is considered to be several days to several months, the upper limit of the allowable power application rate may be regarded as about 100%. Further, the operation start voltage V _nmA in the current range of 1 to 2 _mA is closely related to the flashover voltage for the lightning impulse. In other words, the lightning impulse flashover voltage as the lightning arrester device is expressed as a value obtained by adding the effect of the resistance element 10 to the flashover voltage of the air discharge gap G alone. Here, when the influence is called a bias voltage, the bias voltage is experimentally almost equal to the operation start voltage V.
It is clear that it is equal to _nmA . Thus, the lightning arrester device in which the operation start voltage V _nmA is set higher _{than the} ground voltage V _o , and the lightning arrester insulator using the small resistance element 10 which is set equal to the practically lower limit as in the present invention. It has been clarified experimentally that the lightning impulse flashover voltage of the present invention is lower than that of the apparatus. For this reason, the insulation coordination characteristics with respect to the insulator devices arranged side by side even in devices having the same air discharge gap length are improved.

The present invention is not limited to the above embodiment, but may be embodied by slightly changing the set current of the operation start voltage corresponding to the diameter of each resistance element from the aforementioned value.

[0029]

As described in detail above, the present invention can prevent the failure of the resistance element in the lightning arrester even in the event of an abnormality such as when the air discharge gap is short-circuited by a wire or the like. This has the effect of reducing the impulse flashover voltage and improving the insulation coordination characteristics for the juxtaposed insulator devices.

[Brief description of the drawings]

FIG. 1 is a graph showing non-linear characteristics of voltage and current of a resistance element.

FIG. 2 is a front view showing an embodiment embodying the lightning arrester insulator device of the present invention.

[Explanation of symbols]

9 Lightning arrester, 10 resistance element, G air discharge gap, V
Operation start voltage of _nA resistance element in 1-2A current range, V _S
The normal phase rise voltage at the time of one line ground fault of the transmission line, the operation start voltage of the V _nmA resistance element in the 1-2 mA current range, and the ground voltage in the normal state of the V ₀ line.

Claims (1)

(57) [Claims] 1. A lightning arrester having a built-in resistance element having a non-linear voltage-current characteristic is mounted on a transmission line, and an air discharge gap is provided between the power application side and the transmission line side of the lightning arrester. In the lightning arrester insulator device, based on the characteristics of the resistance element of the lightning arrester, the starting voltage of the resistance element in the current range of 1 to 2 A is V _nA , and Assuming that the healthy phase rise voltage at the time of the fault is V _S , the following equation is set: V _nA ≧ V _S, and the operation start voltage in the current range of 1 to 2 mA is V _nmA , where V ₀ is the ground voltage of the line in the normal state, the following _equation is established: V _nmA ≒ V ₀ .