JPS63296315A - Arrester - Google Patents

Abstract

PURPOSE:To improve the heat-dissipating characteristics of a varistor element by fixing the cylindrical varistor element and a coil-shaped spring positioned at the fixing section of a power equipment through an insulating rod extending from the power equipment, leading out electric terminals from both ends of the insulating rod and directly bringing insulating oil in a tank for the power equipment into contact with the varistor element. CONSTITUTION:A coil-shaped spring 16 is mounted between a fitting 28 and a grounding terminal 19, and mutually pressure-welds a varistor element 15 while fastening the whole arrester. The insulating rod 17 is fixed to the L-shaped fitting 28 set up onto a core 26 for a transformer, and the insulating rod 17 is dipped in insulating oil. The element temperatures of the varistor elements 15 are elevated extremely in the same manner as conventional devices by energy absorbed, but heat from each varistor element 15 is dissipated uniformly into the insulating oil 27 in a tank 22 directly, the specific gravity of the insulating oil 27 exposed at a high temperature is lightened, and the beltlike flow of the insulating oil 27 is formed along the outer faces of the varistor elements 15 to an upper section from a lower section. Accordingly, the effect of heat dissipation from the varistor elements is improved largely.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a lightning arrester for use in oil for protecting power equipment from abnormal voltages such as lightning surges.

BACKGROUND OF THE INVENTION In recent years, in the electric power field, the demand for a stable supply of electric power has increased more than ever before, and efforts have been made to improve the reliability of electric power equipment and the quality of electric power.

In particular, in order to improve the quality of electric power, zinc oxide type lightning arresters without series gaps have been put into practical use in order to reliably absorb harmful abnormal voltages generated on power transmission and distribution lines due to lightning, etc. installed in various locations. Also,
From the viewpoint of economically improving the protection characteristics of power equipment, lightning arresters built into power equipment are also being put into practical use. This type of lightning arrester built into power equipment is typically used in transformers submerged in oil, but these arresters are constantly exposed to the high temperature of the insulating oil of the transformer, and the temperature is higher when applied in air. Therefore, sufficient heat dissipation must be considered for surge current absorption and short-term AC overvoltage application.

Therefore, how to dissipate the heat generated from the elements that are the characteristic elements of lightning arresters has become an important issue.

Conventionally, the internal structure of this type of lightning arrester was as shown in FIG. The lightning arrester shown in FIG. 3 is an example of a transformer applied in oil, and some of the components of the transformer are also shown. In Fig. 3, 1 is a cylindrical varistor element obtained by high-temperature sintering using zinc oxide as the main raw material, adding additives such as bismuth and praseodymium, and in the example shown in the figure, 4 pieces are connected in series by pressure welding. has been done. 2 is a coiled spring that fixes and presses the varistor element 1; 3 is the varistor element 1;
It is also an insulating case that houses the spring 2, and usually a hollow insulator is used. 4 is the same road, the charging terminal of the lightning device,
Reference numeral 6 denotes a metal cover and a puffer that seal and fix the entire contents stored in the insulating case 3.
Fixed. 6 is an oil hole provided on the charging terminal side of the insulation cooler 23, 7 is a ground terminal, 8 is a ground lead wire from the ground terminal 7, and 9 is a tank of the transformer, to which the ground lead wire 8 is connected. The tank 9 itself is also grounded to the ground. 10 is a charging lead wire connected to the charging terminal 4;
Reference numeral 11 denotes an insulating plate made of an insulator, and provided with voltage tap switching terminals of a transformer, etc. A high voltage lead wire 12 is connected to the charging lead wire 10 on the insulating plate 11, and is also connected to a high voltage winding (not shown) of the transformer.

13 is the iron core of the transformer, 14 is filled with insulating oil up to the part indicated by the broken line A, and the entire lightning arrester is contained in this insulating oil 14.

Regarding the heat dissipation of the conventional lightning arrester configured as above,
The operation will be explained below.

First, when lightning surge voltage, switching surge voltage, or short-time AC overvoltage is applied across the arrester, the surge current associated with those voltages is bypassed by the arrester, and the surge voltage on the line to which the arrester is connected is suppressed. . At this time, the surge current passes through the varistor elements 1 connected in series, and the energy consumed at that time becomes Joule heat, which temporarily increases the temperature of the varistor element 1, and then mainly the side surfaces of the varistor element 1. Insulated case 3
Heat is radiated to the insulating oil 14 inside, and further heat is radiated by passing the oil through the insulating case 3 and the oil passage holes 6.

Problems to be Solved by the Invention However, with such a conventional configuration, 1. When the above-mentioned surge voltage or short-time AC overvoltage occurs continuously or for a long time, there is a problem that heat dissipation by passing oil through the insulating case 3 and the oil passage hole 6 is not sufficient. That is, in the conventional configuration,
This is because the flow of the insulating oil, which is a heat transfer medium, is limited to the vicinity of the oil passage hole 6, and the flow of the insulating oil at the side surface of the varistor element 1 is hardly expected.

The present invention aims to solve these problems,
The purpose of this is to enhance the heat dissipation characteristics of the varistor element through the flow of insulating oil surrounding the varistor element, thereby increasing the thermal stability of the lightning arrester when handling large amounts of energy.

Another objective is to provide a lightning arrester that is resistant to mechanical vibrations and shocks that are expected to occur during transportation.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention fixes a cylindrical varistor element and a coiled spring located at a fixed part of a power device via an insulating rod extending from the power device. Electrical terminals are taken out from both ends of the varistor element so that the insulating oil in the tank of the power equipment comes into direct contact with the varistor element.

Effect of the Invention With the above-described configuration, the insulating oil heated by the heat generated by the varistor element has a light specific gravity, and the insulating oil can uniformly flow upward from the bottom to the top along the outer surface of the varistor element. This greatly improves the heat dissipation effect from the side surfaces of the varistor element. Further, the coiled spring has the function of pressing against the varistor element and at the same time has the function of absorbing mechanical vibrations and shocks applied perpendicularly to the axis of the insulating rod.

Embodiment FIG. 1 is a sectional view showing a lightning arrester according to an embodiment of the present invention, and is an example of application in transformer oil. In Figure 1, 1
Reference numeral 5 denotes a varistor element whose main material is zinc oxide, which has a hollow cylindrical shape, and a ring-shaped metallicon electrode is provided on each end surface of the varistor element.

Further, in FIG. 1, four varistor elements 15 are connected in series. A coiled spring 16 is provided between a metal fitting 28 and a ground terminal 19, which will be described later, to press the varistor elements 15 together and fix the entire lightning arrester at the same time. Reference numeral 17 denotes an insulating rod, one of which is fixed to an L-shaped metal fitting 28 attached to an iron core 26 of a transformer, which will be described later. Since this insulating rod 17 is immersed in insulating oil, a resin or ceramic rod with good oil resistance, or a metal rod coated with an insulating coating is used. 18 is a stopper, insulating rod 1
7 is fixed. The pressing force of the spring 16 is controlled by adjusting this fixed position.

Reference numeral 19 denotes a ground terminal, which is brought out in pressure contact with the electrode of the varistor element 15 located at the end adjacent to the spring 16. 2o is a charging terminal, which is drawn out in contact with the electrode of the varistor element 15 located at the other end. 21 is a ground lead wire, 22 is a tank, 23 is a charging lead wire, 24 is an insulating plate, 26 is a high voltage lead wire, 26 is a transformer core, 27 is an insulating oil, and these are the conventional ground lead wire 8, It corresponds to the tank 9, charging lead wire 10, insulating plate 11, high voltage lead wire 12, iron core 13, and insulating oil 14.

Next, the operation of the lightning arrester configured as above will be explained. Now, as in the conventional example, if a surge voltage or short-time AC overvoltage occurs continuously or for a long time, the element temperature of the varistor element 16 becomes extremely high due to the absorbed energy, as in the conventional example. However, heat radiation from each varistor element 16 is uniformly performed directly to the insulating oil 27 in the tank 22, and the insulating oil 27 exposed to high temperature
The specific gravity of the varistor element 16 becomes lighter from the bottom to the top.
A band-shaped flow of insulating oil 27 is formed along the outer surface of the insulating oil 27. Further, this band-shaped flow has a characteristic that the higher the temperature rise of the varistor element 15, the faster the flow becomes. In this way, the heat removal effect of the varistor element 15 is greatly improved,
The temperature rise of the varistor element 16 can be suppressed to a low level,
As a result, good thermal stability can be obtained, such as being able to avoid thermal runaway of the lightning arrester in the rated AC application state. In addition, since the ground terminal 19 is drawn out directly from the varistor element 16, the inductance component caused by the conventional spring is eliminated, and the steep wave limiting voltage can be reduced. It also has economical effects, such as a simple structure and a small number of parts.

Further, the spring 16 acts as a cushion against mechanical vibrations and shocks applied perpendicularly to the axis of the insulating rod 17, and has the effect of preventing cracking of the edge portion of the varistor element 15 due to bending moment.

Next, a second embodiment of the present invention will be described with reference to FIG. The difference from the embodiment shown in FIG. 1 is that two lightning arresters of the present invention are combined into one. In FIG. 2, M and B are respectively 1. 29 is the second lightning arrester, both lightning arresters, B
30 is a charging terminal of lightning arrester A, and 31 is a charging terminal of lightning arrester B. Here, the basic operation is the same as the first embodiment, but generally two lightning arresters are used in the built-in transformer type, but as shown in FIG.
By combining the second lightning arrester M, B, the structure can be made compact and economical.

In the embodiment of the present invention, the main body of the arrester is located on the iron core, but it goes without saying that the same effect can be obtained by attaching an insulating rod to the tank and attaching the arrester to the inner surface of the tank. Also, in this example, the installation was done horizontally, but
This is true whether it is installed diagonally or vertically.

Effects of the Invention As described above, according to the present invention, a cylindrical varistor element and a coiled spring located at a fixed part of a power device are fixed via an insulating rod extending from the power device, and electrical terminals are connected from both ends of the coil spring. When the insulating oil in the tank of the power equipment comes into direct contact with the varistor element, the Joule heat generated within the varistor element can be quickly dissipated, suppressing the temperature rise of the varistor element, and as a result, improving the quality of the lightning arrester. This has the effect of ensuring good thermal stability and suppressing deterioration of characteristics of varistor elements, and also has the effect of reducing steep wave limiting voltage and realizing economical manufacturing of lightning arresters.

Also, against vibrations and shocks applied perpendicular to the axis of the insulating rod,
The spring acts as a cushion and has the effect of preventing the edge portion of the varistor element from cracking due to bending moment.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a lightning arrester according to an embodiment of the present invention;
FIG. 2 is a sectional view showing a lightning arrester according to a second embodiment of the present invention, and FIG. 3 is a sectional view showing a conventional lightning arrester. 16... Varistor element, 16... Coiled spring, 17... Insulating rod, 18...
...Strike, power, 19, 29...Grounding terminal, 20,30.31...Charging terminal, 22.
... Tank, 26 ... Transformer core, 2
7...Insulating oil. Name of agent: Patent attorney Toshio Nakao and 1 other person15
--゛Power Surge Element 20 Charging Terminal Figure 1 Figure 2

Claims (1)

[Claims] A hollow part of a cylindrical varistor element in which one or more insulating rods extending from a part of the power equipment are stacked in series, and a coiled spring located between a fixed part of the power equipment and the varistor element. The varistor element is fixed by pressure through the hollow part, and each electric terminal is taken out from both ends of the varistor element, so that the varistor element is directly in contact with insulating oil in the tank of the power equipment. lightning arrester.