JP2004288671A - Method of manufacturing polymer lightning arrester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of voids at the time of manufacturing a polymer lightning arrester by molding liquid silicone rubber. <P>SOLUTION: When a plurality of plate-shaped insulating boards 4 is disposed almost horizontally in the upper part of the internal space 8 of metal molds 1 and 2 by providing a gap between adjacent insulating boards 4, so that the gap may be faced to an inlet port 6 at the time of injecting the liquid silicone rubber into the internal space 8 from the downside, while a laminated zinc oxide element 3 and the insulating boards 4 are held in horizontal states in the internal space 8, the height positions of the upper ends of the insulating boards 4 sandwiching the zinc oxide element 3 from the horizontal direction are made lower than that of the upper end of the element 3 by h so that the liquid silicon rubber may first reach the centers of the lower surfaces of the almost horizontal insulating boards 4 after rising along the surface of the element 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a polymer lightning arrester.
[0002]
[Prior art]
Since the present invention is an invention developed based on a publicly known / public technology without conducting a search for the prior art, the prior art known by the applicant does not correspond to a publicly known invention. Hereinafter, a method for producing a publicly known and publicly used polymer lightning arrester will be described.
[0003]
Polymer type surge arresters used for electric power are laminated with zinc oxide elements, and the laminated zinc oxide elements are covered with a flat or arc-shaped insulating plate made of an insulating material such as FRP. For example, a zinc oxide element and an insulating plate are molded with a liquid silicone rubber to give a lightning arrester necessary pressure release performance and strength.
[0004]
As a problem when manufacturing such a polymer type lightning arrester, there is a problem that when molding with liquid silicone rubber, the liquid silicone rubber is not completely filled in the internal space and a space remains. This space is called a void. If there is a void, there is a problem that a partial discharge occurs during the operation of the polymer lightning arrester or that moisture is accumulated in the void and the withstand voltage characteristic is reduced. The reason why voids occur is that liquid silicone rubber is filled from both sides so as to sandwich air between the insulating plate and the zinc oxide element, and there is no escape path for air, and the air remains.
[0005]
To solve this problem, it is effective to make the gap between the insulating plates large enough to smooth the flow of the liquid silicone rubber inside the insulating plate. As the external dimensions increase and the cost increases, the function of the pressure relief characteristics that prevents the zinc oxide element from scattering to the outside when the surge arrester processes and destroys a surge exceeding the expected debt is reduced. However, if one is established, the other is not established, and it is a problem how to balance these conflicting demands.
[0006]
FIGS. 7 and 8 show a method of manufacturing a conventional polymer lightning arrester as Conventional Examples 1.2. FIG. 7 shows the use of three flat insulating plates, and FIG. 8 shows the use of four flat insulating plates. In each case, three or four insulating plates 4 are arranged in the inner spaces 8 of the left and right molds 1 and 2 so as to surround the zinc oxide element 3, and the lower insulating plate 4 is arranged in a horizontal state. An inlet 6 for liquid silicone rubber 5 is provided below the insulating plate 4. When the liquid silicone rubber 5 is injected from the inlet 6, since the air vent hole 7 is provided at the upper part, the liquid silicone rubber 5 is filled and molded in order from (a) to (d) in FIGS. .
[0007]
[Problems to be solved by the invention]
However, in both FIGS. 7 and 8, a void 7a is formed at the center of the upper surface of the lower horizontal insulating plate 4, and in the case of FIG. 8, a void 7b is also formed at the center of the lower surface of the upper horizontal insulating plate 4.
[0008]
Therefore, an object of the present invention is to provide a method for manufacturing a polymer lightning arrester that has solved the above-mentioned problems.
[0009]
[Means for Solving the Problems]
The method for manufacturing a polymer lightning arrester according to claim 1, wherein the stacked zinc oxide element and a plurality of insulating plates surrounding the zinc oxide element are held in a substantially horizontal direction in the interior space of the mold, and In a method of manufacturing a polymer lightning arrester in which a polymer material for molding a zinc oxide element and an insulating plate is injected into the internal space from below, a gap is provided between adjacent ones of the insulating plate, and the polymer material is injected. Characterized in that one of the gaps is opposed to an injection port to be formed.
[0010]
In such a method for manufacturing a polymer lightning arrester, the polymer material injected into the interior space of the mold from the injection port enters the inside and outside of the insulating plate surrounding the zinc oxide element because the gap faces the injection port. Therefore, no void is generated.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a method for manufacturing a polymer lightning arrester according to the present invention will be described.
[0012]
(A) Embodiment 1
First, Embodiment 1 is shown in FIGS. An internal space 8 is formed inside the molds 1 and 2 in a state where the molds 1 and 2 are combined. The internal space 8 includes a substantially cylindrical body 8a and a plurality of caps 8b. An injection port 6 for injecting liquid silicone rubber as a polymer material from below the molds 1 and 2 is formed at a lower portion of each cap portion 8b, and an air vent hole 7 is provided at an upper portion of each cap portion 8b. Are formed individually. These inlets 6 and air vent holes 7 are necessarily provided at regular intervals because the cap portions 8b are provided at equal intervals.
[0013]
As shown in FIG. 1B, a pair of electrodes 9 and 10 are accommodated at both ends of the internal space 8, and a plurality of zinc oxide elements 3 and the like are stacked horizontally between the pair of electrodes 9 and 10. Three flat insulating plates 4 are arranged in the horizontal direction so as to surround the stacked zinc oxide elements 3, and are held by holding means (not shown). More specifically, a gap is provided between adjacent ones of the three insulating plates 4, the substantially horizontal insulating plate 4 is not disposed below the internal space 8, and the lower insulating plate 4 is inverted. It is arranged in the shape of "C". On the other hand, since three insulating plates 4 are used, a substantially horizontal insulating plate 4 is inevitably disposed at the upper part. As a result, the lower part of the gap between the insulating plates 4 faces the inlet 6.
[0014]
When the gap between the adjacent insulating plates 4 is a, an experiment was conducted by changing the value of a, and it was found that the following results were obtained.
[1] a <1 mm voids are generated.
[2] 5 ≦ a ≦ 10 mm ··· No scattering of zinc oxide elements during large current pressure release test.
[3] a = 15 mm ... Depending on the test conditions (current value, first wave peak value), the zinc oxide element is scattered.
[4] a = 20 mm: Although there are variations due to the test, the zinc oxide element often scatters.
[0015]
From the above, in the present embodiment, the value of a is set in the range of 1 ≦ a <20. With such a setting, as a result, the height position of the upper end of the insulating plate 4 disposed on both sides of the zinc oxide element 3 so as to sandwich it from the horizontal direction is lower than the height position of the upper end of the zinc oxide element 3. Will be.
[0016]
When the liquid silicone rubber is injected from the injection port 6 in the state set as described above, since the air vent holes 7 are formed, the liquid silicone rubber is injected and filled in order from below the internal space 8. Specifically, the liquid silicone rubber flows in the order of FIGS. The liquid silicone rubber 5 injected into the inner spaces of the molds 1 and 2 from below flows upward along the inclined surface of the insulating plate 4 and the arc surface of the zinc oxide element 3 as shown in FIG. There is no void since there is no substantially horizontal surface at the bottom. Although the substantially horizontal insulating plate 4 exists at the upper part, the position of the upper end of the zinc oxide element 3 is higher than the height position of the upper end of the insulating plate 4 disposed on both sides sandwiching the zinc oxide element 3 from the horizontal direction. The liquid silicone rubber 5 rises up to the upper end along the arc surface of the zinc oxide element 3 and adheres to the lower surface of the central portion of the substantially horizontal insulating plate 4, and then goes from the center of the lower surface of the insulating plate 4 to the outside. Will spread on the surface. For this reason, the air existing in the center of the lower surface of the substantially horizontal insulating plate 4 is sequentially pushed outward, and no void is generated.
[0017]
A plurality of inlets are not necessarily required, but when a plurality of inlets are provided, they need to be arranged at substantially equal intervals. The inlet may be formed in the body 8a instead of the cap 8b. When the injection amount of the liquid silicone rubber exceeds approximately 2.5 liters, it is desirable from experience to provide a plurality of injection ports 6 in the molds 1 and 2. By providing a plurality of inlets 6, the injection time of the liquid silicone rubber is reduced.
[0018]
Since the injection time and the curing time vary depending on the properties of the liquid silicone rubber, the number and installation intervals of the injection ports 6 cannot be specified, but the injection time is determined by the viscosity and the injection amount of the liquid silicone rubber. The size and number of the injection ports 6 are set so that the injection time determined by the physical properties and the injection amount of the liquid silicone rubber does not exceed the general physical properties t (10) of the polymer material. Here, the general physical property t (10) is a curing property of the rubber measured by a rheometer or a curast meter, and refers to a vulcanization start point or a moldable time, that is, a time until curing starts. Since the size and number of the injection ports 6 are set so as not to exceed the general physical property t (10) of the polymer material, the injection time of the liquid silicone rubber is reduced.
[0019]
Since the plurality of inlets 6 are arranged at substantially equal intervals in the length direction of the lightning arrester, the liquid silicone rubber is uniformly injected in the length direction of the lightning arrester, and the injection operation is stabilized.
[0020]
Experience has shown that voids are less likely to occur when the air vent holes 7 provided in the molds 1 and 2 are provided in each cap portion 8b to form a plurality.
[0021]
(B) Embodiment 2
Next, a second embodiment is shown in FIG. The second embodiment is a partial modification of the first embodiment. Therefore, the description of the same portions will be omitted, and only different portions will be described.
[0022]
In the second embodiment, as shown in FIG. 2, every other injection port 6 is provided without providing the injection port 6 in all of the cap portion 8b.
[0023]
Other configurations and operations are the same as those of the first embodiment, and therefore, description thereof will be omitted.
[0024]
(C) Embodiment 3
Next, a third embodiment is shown in FIG. In the third embodiment, a part of the first embodiment is modified. Therefore, the description of the same portions will be omitted, and only different portions will be described.
[0025]
As shown in FIG. 3, the present embodiment uses four flat insulating plates 4. When four flat insulating plates 4 are used, the insulating plate 4 becomes a quadrilateral. Therefore, when the insulating plate 4 is arranged in an inverted "C" shape at the lower part of the internal space 8, it is arranged in a "C" shape at the upper part. Thus, the insulating plate 4 is not disposed substantially horizontally. Therefore, as in Embodiment 1, the value of a may be set in the range of 1 ≦ a <20, but the value of a is not particularly set as long as the liquid silicone rubber can pass through. good. That is, when the insulating plate 4 is not arranged substantially horizontally, the value of a is not specified.
[0026]
When the liquid silicone rubber is injected from the injection port 6 in the state set as described above, since the air vent holes 7 are formed, the liquid silicone rubber is injected and filled in order from below the internal space 8. Specifically, the liquid silicone rubber flows in the order of FIGS. The liquid silicone rubber 5 injected into the internal spaces 8 of the molds 1 and 2 from below flows upward along the inclined surface of the insulating plate 4 and the arc surface of the zinc oxide element 3 as shown in FIG. Since neither the lower nor upper part of the internal space 8 has a substantially horizontal surface, no void is generated.
[0027]
Other configurations and operations are the same as those of the first embodiment, and therefore, description thereof will be omitted.
[0028]
(D) Embodiment 4
Next, a fourth embodiment will be described. The fourth embodiment is a modification of the third embodiment. Therefore, the description of the same portions will be omitted, and only different portions will be described.
[0029]
In the fourth embodiment, the inlets 6 are not provided in all of the cap portions 8b in the third embodiment, but every other inlet 6 is provided as in FIG.
[0030]
Other configurations and operations are the same as those of the third embodiment, and therefore, description thereof is omitted.
[0031]
(E) Embodiments 5 and 6
Finally, Embodiments 5 and 6 will be described. In these embodiments, as shown in FIG. 6, four arc-shaped insulating plates are used in place of the four flat insulating plates in FIG. 3B. In this case as well, the same as in the third and fourth embodiments, there is no void since there is no substantially horizontal surface in the lower part and the upper part of the internal space 8.
[0032]
The other configuration and operation are the same as those of the third and fourth embodiments, and thus the description is omitted.
[0033]
The polymer material is not limited to liquid silicone rubber, and various materials can be used.
[0034]
【The invention's effect】
As can be seen from the above description, according to the method for manufacturing a polymer lightning arrester according to the present invention, a gap is provided between adjacent ones of the insulating plate, and any of the gaps is provided at an inlet for injecting the polymer material. Since they face each other, no void occurs in the polymer lightning arrester molded with the polymer material.
[Brief description of the drawings]
1A and 1B are a front sectional view and a side sectional view, respectively, of a mold according to a first embodiment of a method for manufacturing a polymer lightning arrester according to the present invention.
FIG. 2 is a front sectional view showing Embodiment 2 of the method for manufacturing a polymer lightning arrester according to the present invention.
3 (a) is a front sectional view of a mold, and FIG. 3 (b) is a side sectional view, according to Embodiment 3 of the method for manufacturing a polymer lightning arrester according to the present invention.
FIG. 4 is an operation explanatory view of Embodiment 1 of the method for manufacturing a polymer lightning arrester according to the present invention.
FIG. 5 is an operation explanatory view of Embodiment 3 of the method for manufacturing a polymer lightning arrester according to the present invention.
FIG. 6 is a side sectional view of a mold showing Embodiments 5 and 6 of a method for manufacturing a polymer lightning arrester according to the present invention. FIG. 7 is an explanatory view of a method for manufacturing a polymer lightning arrester according to Conventional Example 1.
FIG. 8 is an explanatory view of a method for manufacturing a polymer lightning arrester according to Conventional Example 2.
[Explanation of symbols]
1, 2, mold 3, zinc oxide element 4, insulating plate 8, internal space

Claims (9)

A polymer material for holding the stacked zinc oxide element and a plurality of insulating plates surrounding the zinc oxide element in a substantially horizontal state in the interior space of the mold, and molding the zinc oxide element and the insulating plate. Injecting into the internal space from below,
A method for manufacturing a polymer lightning arrester, wherein a gap is provided between adjacent ones of the insulating plate, and one of the gaps is opposed to an inlet for injecting the polymer material. An insulating plate is disposed substantially horizontally above the internal space, and the height position of the upper end of the insulating plate disposed on both sides sandwiching the zinc oxide element from the horizontal direction is lower than the height position of the upper end of the zinc oxide element. The method for manufacturing a polymer lightning arrester according to claim 1, wherein: The method for manufacturing a polymer lightning arrester according to claim 1, wherein four flat or arc-shaped insulating plates are used as the plurality of insulating plates. The method for manufacturing a polymer lightning arrester according to claim 2, wherein three flat insulating plates are used as the plurality of insulating plates. The method according to claim 1, wherein the gap is set to 1 mm or more and less than 20 mm. The method according to any one of claims 1 to 5, wherein a plurality of injection ports are provided in the mold when the injection amount of the polymer material exceeds approximately 2.5 liters. 7. The size and number of the injection ports are set so that the injection time determined by the physical properties of the polymer material and the injection amount does not exceed the general physical properties t (10) of the polymer material. Manufacturing method of polymer arrester. The method according to claim 7, wherein the inlets are arranged at substantially equal intervals in a horizontal direction. The method according to claim 8, wherein a plurality of air vent holes are provided in an upper portion of the mold.

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