JP4637735B2 - Capacitor - Google Patents

Description

  The present invention relates to a capacitor protection device that improves reliability with respect to the connection between a pressure switch and a case used as a capacitor protection device.

In general, a metallized film capacitor is configured by winding an electrode and a dielectric material in a case, evacuating the case, and then impregnating or filling with insulating oil or insulating gas.
These capacitors are protected by a pressure switch using a change in internal pressure when dielectric breakdown occurs at the end of the life.
A pressure switch having a function as a protective device has a pressure relief valve installed in a case so that when a gas passes through a pressure relief path, a sound is generated to notify an abnormal state (Patent Document 1). ), Or by connecting a bellows to the capacitor case and rotating the lever by the expansion of the bellows according to the pressure change of the insulating oil or gas, turning the contacts on and off, and simultaneously turning the pressure rising and falling contacts on There are things that have been avoided (Patent Document 2), etc., and in each case, the pressure switch is directly attached to the case.
JP 2005-45155 A JP-A-9-7875

The above-mentioned pressure switch is attached by performing through-hole processing for inserting a capillary tube of copper or copper alloy pipe for piping into the case, brazing and joining the capillary tube after inserting it into the case.
Accordingly, this bonding cannot be performed after the insulating oil or insulating gas is sealed inside the capacitor, so it must be performed before the impregnation treatment.
Capacitor impregnation is performed by reducing the inside of the capacitor to a vacuum, drying it at a high temperature, and impregnating it with pressure to efficiently remove moisture affecting the performance of the capacitor and ensure insulation performance. Insulating oil or insulating gas is impregnated or filled.

If a pressure switch is installed before pressure impregnation of the capacitor, products with a bellows pressure switch may be subjected to stress due to pressurization or decompression, resulting in damage to the bellows joint or bellows. is there.
In addition, when the pressure switch is not hermetically sealed, the contact portion of the pressure switch may deteriorate due to oxidation corrosion or the like, resulting in an increase in contact resistance and failure to satisfy performance.
In other words, when the impregnation treatment is performed with a pressure switch attached, the pressure switch may oxidize the contact part during high-temperature drying if it is not airtight, and the vacuum inside the case and the bellows of the pressure switch during vacuum drying A pressure difference is generated, and the joint portion or bellows of the bellows may contract more than specified due to this pressure and may not operate at a predetermined pressure. In addition, when the insulating oil is injected or impregnated, the insulating oil scatters and adheres to the contact portion of the pressure switch, and the contact resistance increases, and the performance may not be satisfied.

  Because of the above problems, there has been a demand for a connection method that is excellent in airtightness and excellent in durability, in which a pressure switch having a bellows structure can be easily attached after sealing oil or insulating gas in a capacitor.

  The present invention solves the above-described problems, and a case in which a capacitor element is housed and filled with insulating oil or insulating gas, and a case attached to the case and operating according to the pressure of the insulating oil or insulating gas. A capacitor with a protective device having a switch mechanism having a single bellows and a contact that operates at a pressure set in accordance with the pressure of insulating oil or insulating gas, the capillary tube of the protective device and the case A sealing plug to be connected is attached to the case, the sealing plug is sealed with a rubber plug with a weak point, the case is sealed, and after filling with the insulating oil or gas, a capillary tube is inserted into the rubber plug with the weak point Then, the capacitor with a protective device is characterized in that the joint is further reinforced with airtight solder.

  Furthermore, the thickness of the weak point portion of the rubber plug with the weak point portion is 0.5 mm or more and 0.83 times the thickness of the capillary tube insertion hole diameter or less. It is.

  In addition, the capacitor is characterized in that the rubber plug with a weak point portion has a hardness of 65 to 75 degrees according to JIS K6253 type A, and the material is silicon rubber or fluorine rubber.

According to the present invention, the pressure switch for protecting the capacitor can be attached after the impregnation treatment, so that the pressure switch can be protected from the environment such as vacuum and high temperature applied during the impregnation treatment, and the reliability can be improved.
Furthermore, since the capacitor manufacturing process can be simplified and the reliability of the pressure switch can be maintained, a highly reliable capacitor can be provided. In the case of an oil-filled capacitor, the material of the rubber plug is made of silicon rubber, making use of swelling and improving airtightness. Further, in the case of a gas-filled capacitor, the hermeticity can be stably maintained by forming the sealing plug with a fluorine rubber having a small gas permeation amount.

The protection device of the present invention will be described below with reference to the accompanying drawings. 1 is a sectional view in which a rubber stopper with a weak point and an external toothed washer are attached to the sealing stopper, FIG. 2 is a partial sectional view of the sealing stopper in which a pressure switch is attached, FIG. 3 is a plan view, a side view, and FIG. 4 is a plan view, a side view, and a sectional view of a sealing plug, FIG. 5 is a plan view of a tooth washer with an external tooth profile, a side view, and FIG. 6 is a schematic view in which a pressure switch is attached to a capacitor case.
As shown in FIG. 6, after housing the capacitor element 11 in the case 12, the case 12 is hermetically welded.
Before housing the capacitor element 11, the case 12 is provided with a through hole for a sealing plug that is sealed with a rubber plug with a weak point on the side wall of the case.
Details thereafter will be described in Examples.

The sealing plug 4 for the rubber plug 2 with the weak point is attached to the case in the through hole of the case 12, and the case side wall and the periphery of the sealing plug 4 are welded with the airtight solder 3. Furthermore, in order to prevent the rubber stopper 2 with the weak point from rising, the external toothed washer 1 is fitted and fixed (see FIG. 1).
The capacitor element 11 housed in the case is dried in a high-temperature vacuum for each case as shown in FIG. 7, and filled with insulating oil and sealed.
Thereafter, by inserting a capillary tube of a pressure switch having a function as a protective device along the hole of the rubber stopper 2 with the weak point, the internal pressure fluctuation can be detected.
Furthermore, between the external toothed tooth washer 1 and the sealing plug 4 is fixed with airtight solder to prevent floating.
With the above process, the pressure switch is installed after the capacitor is vacuum dried at high temperature and filled with insulating oil or insulating gas. The pressure switch can be protected from the vacuum and high temperature environment before installation, and has excellent reliability. Capacitors can be provided.

In this embodiment, the rubber plug 2 with the weak point portion uses silicon rubber having a hardness of 70 degrees according to JIS K6253 type A, and the diameters of the upper surface and the lower surface of the rubber plug 2 with the weak point portion are 13.0 mm, 11.0 mm, and high, respectively. The thickness was set to 8.0 mm.
For insertion work and pressure switch operation test, the insertion hole diameter 10 of the weakened rubber plug 2 has three types of 2.0 mm, 2.5 mm, and 3.0 mm, and each insertion hole diameter has a weak rubber plug. The thickness 8 of the weak point part was prepared 10 types each of 6 types of 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm and 3.0 mm.
Moreover, the insertion hole diameter 10 of the rubber plug 2 with the weak spot for gas leak test is made into three types of 2.0 mm, 2.5 mm and 3.0 mm, and the weak spot of the rubber plug with the weak spot for each insertion hole diameter. Ten thicknesses 8 of each of four types of 0.4 mm, 0.5 mm, 1.0 mm, and 1.5 mm were produced.
The sealing plug 4 had an insertion hole diameter of 11.8 mm for the rubber plug 2 and an insertion hole depth of 17.5 mm.
The rubber plug 2 with the weak point produced as described above was fitted into the sealing plug 4 attached to the test jig, and a predetermined pressure was applied to confirm gas leakage from the insertion section (see FIG. 10).
Next, clogging and occurrence of abnormality in the rubber plug 2 with the weak point when the capillary tube was penetrated through the rubber plug 2 with the weak point were confirmed. Furthermore, the operation test of the pressure switch was performed by applying a predetermined pressure in the test circuit shown in FIG. 11, and the results shown in Table 1 and Table 2 were obtained.

  As shown in Table 1, when the capillary tube insertion hole diameter is 2.0 mm, an abnormality occurs during insertion when the thickness exceeds 0.75 times. Even when φ2.5 mm or φ3.0 mm exceeds 0.8 or 0.83 times, an abnormality occurs. Further, as shown in Table 2, when the thickness is less than 0.5 mm, the insulating gas permeates and leakage occurs. Therefore, the thickness 8 of the weak point portion of the rubber plug 2 with the weak point portion is suitably in the range of 0.5 mm to 0.83 times the capillary tube insertion hole diameter.

Next, in order to confirm the hardness of the rubber plug 2 with the weak point portion, the material is silicon rubber, and the diameters of the upper surface and the lower surface of the rubber plug 2 with the weak point portion are 13.0 mm, 11.0 mm, and the height, respectively. The thickness 8 of the weakened portion of the rubber plug 2 with the weakened portion is 1.0 mm, the insertion hole diameter is 2.0 mm, and the rubber hardness is 55, 60, 65, 70, as measured by JIS K6253 type A. Ten pieces were produced in seven types of 75, 80, and 85 degrees.
When the rubber plug 2 with the weak point is inserted into the sealing plug 4 attached to the test jig, whether or not the rubber plug 2 is damaged, and the pressure switch operates at a predetermined pressure by inserting the capillary tube into the rubber plug 2 with the weak point A test was conducted.
The diameter of the capillary tube was 2.4 ± 0.2 mm.
As shown in Table 3, when the rubber plug 2 with the weak point portion has a hardness of less than 65 degrees, there is a problem of tearing when the rubber plug is inserted or the capillary tube is inserted, or a malfunction of the pressure switch occurs.
In addition, when the hardness is 80 degrees or more, it is particularly difficult to penetrate the weak point portion of the rubber plug 2 with the weak point portion, which causes a problem of causing clogging.
Accordingly, the hardness of the rubber plug is suitably in the range of 65 to 75 degrees.

The material of the rubber plug 2 with the weak point portion was changed to fluoro rubber, and 10 rubber plugs each having the same shape and hardness as those of the rubber plug hardness test of Example 1 were produced, and the same test was performed. The results are shown in Table 4.
As shown in Table 4, when the hardness is less than 65 degrees, there is a problem of tearing at the time of rubber plug insertion or capillary tube insertion.
Further, when the hardness is 80 degrees or more, in particular, it is difficult to penetrate the weak point portion of the rubber plug 2 with the weak point portion, which causes a problem of causing clogging.
Accordingly, the hardness of the fluororubber plug is suitably in the range of 65 to 75 degrees.

The thickness 8 of the weak part of the rubber plug 2 with the weak part when the material is made of fluoro rubber is that the gas permeation amount of the fluoro rubber is about 1/10 of that of silicon rubber. Since gas leakage is superior to silicon rubber, and because of the hardness test results, the number of failures and the number of breaks were almost the same, so fluoro rubber has the same or better performance than silicon rubber. I can judge.
Moreover, although the rubber stopper 2 with a weak point part and the sealing stopper 4 were made into the shape of the said Example, it is not limited to the shape of a present Example.

It is a cross-sectional surface of a bellows structure pressure switch mounting bracket. It is the partial cross section surface which attached the bellows structure pressure switch. It is the top view a, the side view b, and sectional drawing c of the sealing stopper for rubber insertion with a weak point part. It is the top view a of the rubber stopper with a weak point part, the side view b, and sectional drawing c. It is the top view a and the side view b showing the structure of a washer with an external tooth. It is a structural diagram of the capillary tube of the bellows structure pressure switch. It is a figure showing the individual impregnation process of the product with a pressure switch. It is a figure showing the impregnation process of the product with a pressure switch accommodated in the tank. FIG. 7 is a normal position diagram a of the bellows of the pressure switch, and a diagram b showing the position of the bellows when the pressure is reduced. This is a gas leak test circuit. It is an operation test circuit of a pressure switch.

Explanation of symbols

1 External toothed tooth washer 2 Rubber plug with weak point 3 Airtight solder 4 Sealing plug 5 Upper lid 6 Bellows pressure switch 7 Vacuum, insulating oil or insulating gas 8 Rubber plug thickness 10 Rubber plug insertion hole diameter 11 Capacitor element 12 Case 13 Capillary tube

Claims (3)

A case containing a capacitor element and filled with insulating oil or gas, a single bellows attached to the case and operating in accordance with the pressure of the insulating oil or gas, and insulating oil or gas In a capacitor with a protective device having a switch mechanism with a contact that operates at a pressure set according to the pressure,
A sealing plug that connects the capillary tube of the protective device and the case is attached to the case, the sealing plug is sealed with a rubber plug with a weak point, and the case is sealed, after filling with the insulating oil or insulating gas, A capacitor with a protective device, wherein a capillary tube is inserted into the rubber plug with the weak point, and then the joint is reinforced with airtight solder.   2. The protection according to claim 1, wherein the thickness of the weak point portion of the rubber plug with the weak point portion is 0.5 mm or more and 0.83 times or less the diameter of the capillary tube insertion hole. Capacitor with device. 2. The capacitor with a protective device according to claim 1, wherein the hardness of the rubber plug with a weak point portion is 65 to 75 degrees according to JIS K6253 type A, and the material is silicon rubber or fluorine rubber.

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