JPS6199289A - Lightning arrester - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a lightning arrester without a series gap using a non-linear resistor with excellent voltage-current non-linearity.

In particular, it relates to lightning arresters with improved potential distribution control methods.

[Technical background of the invention and its problems] Non-linear resistors used in lightning arresters are, for example, oxides obtained by molding and firing raw materials containing zinc oxide as a main component and some other metal oxides. There is a zinc varistor. This element is an insulator when a relatively low voltage is applied, and when a commercial frequency AC voltage is applied, the capacitance current is generally larger than the resistance current, and the dielectric constant is 500 to 1000. behaves as a dielectric material. −
When a high voltage such as a lightning surge is applied, the current increases rapidly, and it becomes a low-resistance element that absorbs the energy of the overvoltage and suppresses the overvoltage.

When this type of arrester is in continuous operation, there is no series gap, so a voltage is constantly applied to the element, but that voltage is usually designed to be low to avoid abnormal heat generation of the element, so in this case the element is It behaves like a dielectric material.

When a large number of the above elements are stacked according to the rated voltage of the lightning arrester, the effect of stray capacitance from the element to the ground causes element 1
Non-uniformity occurs in the shared voltage for each element, and the shared voltage becomes larger as the element is placed on the higher voltage side.

By the way, if a voltage is applied to the above element for a long period of time, the resistance valve leakage current gradually increases, and this heat generation causes a rise in temperature. With respect to this element resistance valve leakage current, the resistance-temperature characteristic is negative as in a normal semiconductor, so eventually the balance between heat generation and heat radiation is lost and thermal runaway occurs, resulting in destruction. It is known that the lifespan of this element is shorter as the voltage applied to the element is higher, and furthermore, the required lifespan of the lightning arrester in the actual field must be taken into account, and there is an upper limit to the voltage that can be applied to the element at all times. Therefore, some kind of potential distribution equalization means is required.

The degree of non-uniform potential distribution is determined by the capacitance (Co) of the element itself and the stray capacitance from the element to the ground! (Cs) ratio Cs/Go
The larger Cs/So is, the more uneven the potential distribution becomes. The non-uniformity of the potential distribution becomes greater in tank-type arresters in which the arrester container is made of a grounded metal tank, and in high-voltage arresters in which the number of laminated elements is greater.

Conventionally, this type of lightning arrester has been put into practical use with the following configuration. That is, a grounded metal tank whose upper and lower openings are closed with an insulating spacer and a metal end plate that insulate and support a high-voltage conductor is filled with high-pressure insulating gas, a capacitor tube, and a lightning arrester housed and supported within the capacitor tube. Elements are stored and arranged. The high voltage side of this arrester element is connected to a high voltage conductor, and the ground side is connected to a metal end plate.

■ The lightning arrester element is made by stacking multiple non-linear resistance elements.
The capacitor tube is composed of two series-connected bodies.The capacitor tube has a large number of foil electrodes embedded in an insulating tube, and capacitance is formed in the lapped portion of the capacitors. By gradually decreasing the capacitance, the influence of stray capacitance on the ground potential is compensated for and a uniform potential distribution is achieved.

According to this configuration, a uniform potential distribution is achieved along the stacking direction of the arrester elements, but since voltage is constantly applied to the capacitor tube, extremely high reliability is required of the capacitor tube, and it is very expensive. Become something. Furthermore, as the voltage increases, the capacitance on the high voltage side of the capacitor tube increases, resulting in a larger device and requiring advanced technology to manufacture.

[Object of the Invention] The present invention has been made to eliminate the above-mentioned drawbacks, and can be applied to high voltage ratings without using a capacitor tube.
Another object of the present invention is to obtain a surge arrester that can substantially uniformize the potential distribution along the length of the arrester element even if it is tank-shaped.

[Summary of the Invention] In order to achieve the above object, according to the present invention, a block pillar in which a plurality of element unit blocks formed by stacking a plurality of non-linear resistors are stacked with an insulating plate made of a high dielectric material interposed therebetween.
of these two block pillars, the top surface of the element located at the top of the first element unit block that is attached to the first block pillar, and the element upper surface of the element unit block that belongs to the second block pillar. Parallel connection in which the insulating plate made of the high dielectric material is connected in parallel to the element unit block by connecting one element unit block and the bottom surface of the element located at the bottom of an adjacent second element unit block with a conductive plate. The element unit blocks of the first and second block columns are connected by a conductive plate so that the parallel connected bodies are successively connected in series.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 is a block diagram of a lightning arrester element designated by the general reference numeral 1 used in the lightning arrester of the present invention, and FIG. 2 is a view taken along the line ■-■ in FIG. An element unit block 2 is formed by stacking (three in the example) non-linear resistance elements whose main component is zinc oxide. A plurality of these element unit blocks 2,
Block columns 4 and 5 are formed by stacking them with insulating plates 3 in between. In the illustrated example of actual pressure, three element unit blocks 2 are stacked on the block column 4, and four element unit blocks 2 are stacked on the block column 5 to form the respective block columns. In order to adjust the overall length of both block columns 4 and 5, gold U guides 10 and 1"1 are arranged at the upper and lower parts of the block column 4. In this way, each block column 4 with the same overall length , 5 are placed side by side, and a common metal plate 6.7 is applied to both ends.Then, the two metal plates 6.7 are tightened together by an insulating rod 8 and a nut 9.Thus, both block columns 4
Although the element unit blocks 2 of and 5 are arranged in a staggered manner as shown, these element unit blocks 2 are electrically connected in series.

That is, the element unit processor located at the bottom of the block pillar 5,
A conductive plate 1
Connect at 2A. A conductive plate 12B connects the upper surface of the upper element of the element unit block 2-8 and the lower surface of the lower element in the element unit block above the element unit block 2-A. Similarly, all the unit element blocks 2 are connected in series between the metal plates 6 and 7 by sequentially connecting the unit element blocks of both block columns 4.5 with the conductive plates 12.

FIG. 3 is a plan view (a) showing the specific structure of the conductive plate 12.
) and a side view (b), which are formed by a holding part 120 held between the element and the insulating plate 3, and a connecting part 121 connecting the holding parts 120.

On the other hand, the insulating plate 3 is made of a material with a high dielectric constant, and for example, ceramics containing titanium oxide as a main component and having a dielectric constant of 100 to 200 can be used.

In the above embodiment, a disc-shaped insulating plate similar to the element was described, but as shown in FIGS. 4 and 5, in which the same parts as in FIG. 1 are given the same reference numerals. , a hole 130 that communicates the element unit block 2-B of one block pillar 4.
You may make it use the insulating board 13 which has this. At this time, in the other block pillar 5, the element unit block 2-
It is used so that the insulating plate 13 is located at the end of A.

Next. Now, the operation of the lightning arrester of the present invention constructed as described above will be explained. FIG. 6 shows an electrical equivalent circuit of the lightning arrester element 1 shown in FIG. 1 used in the lightning arrester of the present invention. From this, the self-capacitance of the element unit block 2 is
It can be seen that the capacitance increases from the capacitance of only the non-linear resistance element to the capacitance of the insulating plate 3 added thereto. The same applies to the embodiment shown in FIG. This effect will be quantitatively explained below.

Now, as shown in Fig. 7, the self-capacitance ω per unit length of the arrester element 1 is C (pF/s++), and the stray capacitance with respect to the ground potential per unit length is Cs (pF/a ).

It is known that the potential distribution (x) for this is expressed by the following equation.

E (x) is maximum at X-0k, and its II
Emax is Emax=V - 0taoh (KL) Since the average potential gradient Eave-Vo/f, the overvoltage coefficient η=l:max/Eave is Now, the diameter of the non-wire resistance element is 76In! n, i electric rate is 1
000, and the length of the element block column is 2000 m. This corresponds to a lightning arrester applied to approximately 275kV system. If the diameter of the tank is 700 mm, then

And in the conventional structure where elements are simply stacked, It is.

On the other hand, in the case of the lightning arrester of the present invention, for example, the dielectric constant of the insulating plate 3 is 150. The ratio of the thickness of the insulating plate 3 to the thickness of the unit block 2 is 1=10. Assuming that the diameters of the element and the insulating plate 3 are the same, the following equation is obtained.

In this way, according to the lightning arrester of the present invention, η-1,678
The overvoltage multiple is significantly reduced from η-1°293.

If it is about η-1,293, it is possible to suppress η to about 1.10 by adding a simple shield to the high voltage side, making it possible to omit the capacitor tube.

[Effects of the Invention] As explained above, according to the present invention, the potential distribution can be made uniform with a simple configuration even in a tank type with a high voltage rating without using means such as a capacitor tube, and it is inexpensive. A highly reliable lightning arrester can be constructed.

[Brief explanation of the drawing]

1 is a sectional view of a lightning arrester element of a lightning arrester according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, and FIGS. A plan view and a side view of a conductive plate used in a lightning arrester element, FIG. 4 is a sectional view of a lightning arrester element of a lightning arrester according to another embodiment of the present invention, FIG. 5 is a sectional view taken along the line v-v in FIG. 4, FIG. 6 is a diagram showing an electrical equivalent circuit of the lightning arrester element shown in FIG. 1, and FIG. 7 is an explanatory diagram of a potential distribution calculation circuit of the lightning arrester. 1... Lightning arrester element, 2... Unit element block, 3...
...Insulating plate, 4,5...Block column, 6,7...Metal plate, 8...Insulating rod, 9...Nut, 10.1
1... Metal guide, 12... Conductive plate. Applicant's agent Patent attorney Takehiko Suzue No. 1 Figure 2 Figure 3 (b) = Not =

Claims (2)

[Claims] (1) Two block pillars each made by stacking a plurality of element unit blocks formed by stacking a plurality of non-linear resistors with an insulating plate made of a high dielectric material are placed side by side, and of these two block pillars, the first The top surface of the element located at the top of the first element unit block belonging to the block pillar, and the top of the second element unit block adjacent to the first element unit block in the element unit block belonging to the second block pillar. By connecting the lower surface of the element located at the upper part with a conductive plate, a parallel connection body in which the insulating plates of the high dielectric material are connected in parallel to the element unit block is formed, and this parallel connection body is successively connected in series. A lightning arrester in which the element unit blocks of the first and second block columns are connected by a conductive plate. (2) The lightning arrester according to claim 1, in which the insulating plate is made of ceramics containing titanium oxide as a main component. (3) The lightning arrester according to claim 1, in which the insulating plates of the first block column and the second block column are integrated. Lightning arrester as described in Scope 1.