JPH04334889A - Arresting insulator apparatus provided with aerial discharge interval - Google Patents

Abstract

PURPOSE:To improve insulation cooperative characteristics and thermal stability against lightning surge by using a PTC element, whose electric resistance rises rapidly according to rising of temperature in a specific temperature range, as a resistance element contained in an arresting insulator. CONSTITUTION:An arresting insulator 9 is installed on the supporting arm 1 of an iron tower, in parallel to a suspended insulator array 4, which hangs a electric power line 7, through a connection fitting unit 2 on the earth side. A resistance element 10 with nonlinear current-voltage characteristics is contained. In this voltage proof insulating cylinder. The element 10 increases its electric resistance very quickly together with rising of temperature by means of a PTC element in a specific temperature range. Therefore, a surge voltage normally applied to the insulator 9 is mostly shared by an aerial discharge interval G at a low resistance, a flashover voltage is reduced and insulation cooperative characteristics is improved extremely. When long lightning is received, the temperature rises and the resistance becomes high to relieve the self responsibility, and excellent thermal stability is displayed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is designed to quickly discharge surge current to the ground when a power transmission line is struck by lightning, and to suppress and cut off the subsequent follow-on current to prevent ground faults. The present invention relates to a lightning arrester device equipped with an air discharge gap that can be used.

0002

[Prior Art] Conventionally, a wire support insulator is supported with respect to a grounding object such as a steel tower through a grounding side connecting fitting, and an electric wire is supported on the supporting insulator through a energizing side connecting fitting, and the grounding object A lightning arrester is attached to the side via a mounting adapter, while the power-supplying side connection fitting supports a discharge electrode on the power-supplying side,
In a lightning insulator device in which the lightning insulator supports a discharge electrode on the ground side that faces the discharge electrode on the energized side with a predetermined air discharge gap, the lightning arrester has voltage-current characteristics whose main material is zinc oxide. used a nonlinear resistance element.

0003

[Problem to be Solved by the Invention] The nonlinear resistance element of the above-mentioned lightning arrester exhibits characteristics close to that of an insulator (dielectric) when the voltage acting on it is in a low voltage region such as the operating voltage. In a high-voltage region such as It was known that the value increases to about 120 to 150% of the single value. For this reason, when installing a lightning arrester insulator to an existing electric wire support insulator device, it is sometimes difficult to coordinate insulation with the existing insulator, especially in locations where the number of insulators is small.

On the other hand, when dealing with lightning that lasts longer than expected, the temperature of the element increases due to Joule heat, and the resistance in the low current region decreases. As a result, the amount of follow-on flow increases, making it difficult to block the flow in the air gap. The purpose of this invention is to reduce the lightning impulse flashover voltage of a lightning arrester to improve insulation coordination characteristics with existing insulator devices, and to provide a lightning arrester device equipped with an air discharge gap with excellent thermal stability. It is about providing.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a lightning arrester device having a discharge electrode on the grounding side facing a discharge electrode on the charging side with a predetermined air discharge gap. As a built-in resistance element with non-linear voltage-current characteristics, a PTC element whose electrical resistance rapidly increases as the temperature of the element rises in a specific temperature range is used to reduce the follow-on current following lightning surge current. The temperature at which the PTC element rises and reaches equilibrium when it flows is set within a range that does not exceed the critical temperature at which the PTC element has its maximum resistance value.

[0006]

[Operation] By adopting the above-mentioned means, this invention allows when a lightning surge current enters the electric wire, it flashes over the air discharge gap, flows to the PTC element of the lightning arrester, and is then discharged to the earth via the grounding object. Ru. Further, the follow-on current based on the operating voltage that occurs thereafter is suppressed and interrupted by the current limiting effect due to the increase in the resistance value of the PTC element and the insulation of the air discharge gap. At this time, since the resistance element is formed by a PTC element, the resistance is usually overwhelmingly smaller than that of a zinc oxide element, so most of the surge voltage applied to the lightning arrester is distributed to the air discharge gap. Therefore, the lightning impulse flashover voltage is significantly lower than that of the conventional example, and becomes substantially close to the value of the air discharge gap alone. On the other hand, when the temperature of the PTC element rises due to the follow current based on the operating voltage, the resistance value increases and the follow current is limited, thereby improving the ability of the air discharge gap to interrupt the follow current.

[0007] Furthermore, even when dealing with long-duration lightning surges, the temperature-resistance characteristics of the PTC element act to reduce its own responsibility, so thermal runaway does not lead to destruction.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will be described below with reference to the drawings. As shown in FIG. 2, a suspension insulator chain 4 as a support insulator is suspended from a support arm 1 of a steel tower, which is made up of suspension insulators 3 connected in series through a connecting fitting unit 2 on the ground side. A power transmission line 7 is supported at the lower end of this suspended insulator chain 4 via a hanging metal unit 5 and a wire clamp 6 on the power supply side. Further, a lightning arrester 9 is attached to the ground side connecting fitting unit 2 by a mounting adapter 8. This lightning arrester 9 accommodates a resistance element 10 with non-linear voltage-current characteristics in a voltage-resistant insulating tube (not shown), and has electrode fittings 11 and 12 on the grounding side and the charging side fitted to both ends of the insulating tube. However, it is constructed by covering the outside with an insulating jacket 13 made of rubber or the like.

A discharge electrode 14 on the power supply side is supported by the connection fitting unit 5 on the power supply side, and the lower end of the lightning arrester 9 is grounded so as to face the discharge electrode 14 with a predetermined discharge gap G. The side discharge electrode 15 is supported. Incidentally, arc horns 16 and 17 are supported on both the connecting fitting units 2 and 5 to prevent burnout of the suspended insulator chain 4 during creeping flashover. Additionally, an arc horn 18 is provided on the mounting adapter 8 and the power-side electrode fitting 12 to prevent burnout during creeping flashover of the lightning arrester 9.
, 19 are supported. 20 is a balance weight.

Next, the characteristics of the nonlinear resistance element 10, which is the essential part of the present invention, will be explained in detail. In this embodiment, the resistance element 10 is made of PTC (Positive Temperature Carbon), which has nonlinear temperature-resistivity characteristics as shown in FIG.
ture Coeffi-cient) elements are used. This PTC element exhibits an extremely rapid increase in electrical resistance from a value of 100Ω or less to 1MΩ or more in a specific temperature range as the temperature increases. In addition, this PTC element is made of high-purity barium titanate (BaT).
iO3), rare earth elements (La, Da, Nd, Ce, etc.) are added as additives to make it a semiconductor, and a small amount of manganese, chromium, or boron is added as an additive to improve resistance steepness, and then sintered. It is a bonded ceramic. In particular, it is important to sinter in an atmosphere with a high oxygen concentration during cooling and to form a ferroelectric layer at the interface.

[0011] Since the PTC element has a low resistance under normal conditions, most of the surge voltage applied to the lightning arrester device is distributed to the air discharge gap, which reduces the flashover voltage and improves the insulation coordination characteristics. Much improved. In addition, in the event that it is struck by lightning for a long period of time, the processing energy causes the temperature to rise and it becomes a high-resistance material, which has the characteristic of reducing the processing energy and trying to balance itself. In addition, if the air discharge gap G is short-circuited,
It equilibrates at the temperature corresponding to the operating voltage, has self-fail-safe performance, and has excellent thermal stability.

By the way, once the voltage V applied to the resistance element 10 and the current I that can flow are determined, the minimum resistance value Rmin
is decided. Here, in the ρ-t characteristic, the resistivity ρ corresponding to the healthy phase rising voltage at the time of a single-line ground fault is the maximum resistivity ρm
set at a temperature lower than the critical temperature t corresponding to ax,
In addition, the minimum resistance Rmin of the entire resistance element group is set to 10Ap or less, which is the upper limit of the current flowing under the healthy phase rising voltage V1LG at the time of a single line ground fault, which is the upper limit for blocking the following current at the air discharge gap. For example, in a 154kV electric line,

[0013]

[Math. 1] V1LG = 161kV (rms)

0014
]

[Math. 2] Rmin = V1LG ・√2/I=161・√2
/10×10−3=23kΩ. Furthermore, to explain with a specific example, in the case of a PTC element having a maximum resistance ρmax at 150°C, the length L of the laminated disc-shaped resistance element 10 is 850 mm from the withstand voltage value, and the diameter D is from the energy duty side. If it is 47 mm, the cross-sectional area S of the element 10 is 1
It becomes 7.7cm2. And the resistance R is R=ρ・L/
Since S=ρ・K, K is 85.0/17.7=
It becomes 4.80. Here, ρ is 2.4 at a temperature of 20°C.
×101 = 24Ω・cm, 8.0×10 at 150℃
5=8.0×106 Ω·cm. As a result, the resistance R is 150Ω when the temperature is 20°C, and 38Ω when the temperature is 150°C.
It becomes 4MΩ.

It should be noted that the present invention is not limited to the above-mentioned embodiments. For example, since the assumed lightning strike conditions differ depending on the line voltage, the diameter and length of the element may be changed, or a PTC having characteristics suitable for that purpose may be used. The configuration can be modified and embodied as desired without departing from the gist of the invention, such as by using different elements.

[0016]

[Effects of the Invention] As described in detail above, the present invention improves the insulation coordination characteristics and thermal stability characteristics of the lightning arrester against lightning surges, making it highly reliable, and making it possible to improve the insulation coordination characteristics and thermal stability characteristics of the lightning arrester against lightning surges. It has the advantage of being easy to apply.

[Brief explanation of the drawing]

FIG. 1 is a graph showing temperature-resistance characteristics of a resistance element of the present invention.

FIG. 2 is a front view showing the entire lightning arrester device.

[Explanation of symbols]

9 lightning insulator, 10 non-linear resistance element, 14 energizing side discharge electrode, 15 grounding side discharge electrode, G air discharge gap.

Claims (1)

[Claims] 1. A lightning arrester device having a discharge electrode on a grounding side facing a discharge electrode on a charging side with a predetermined air discharge gap, the lightning arrester having a resistor having non-linear voltage-current characteristics built in the lightning arrester; As a device, PTC exhibits a rapid increase in electrical resistance as the temperature of the device increases within a specific temperature range.
The temperature at which the PTC element rises and becomes balanced when a follow-on current following a lightning surge current flows is set within a range that does not exceed a critical temperature at which the PTC element has a maximum resistance value. Lightning arrester device with medium discharge gap.