JPH0546260Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Purpose of the invention This invention relates to a molded capacitor whose inside is filled with insulating gas.

[Prior art] So-called wound capacitor elements, in which a plastic film is used as a dielectric and a metallized film on which a metal is deposited are stacked and wound, are used for electric power because they are non-polar and have low dielectric loss. used for. However, it is well known that when used under high voltage, corona discharge tends to occur at both ends of the winding.

By the way, there is a method for manufacturing a molded capacitor described in JP-A-60-72212, which aims to improve the corona discharge characteristics by retaining an insulating gas on both ends of the winding of a wound capacitor element.

This manufacturing method involves placing a capacitor element in a high-temperature vacuum tank, performing heat treatment and vacuum treatment, filling the treated capacitor element with an insulating gas, and embedding the capacitor element filled with the insulating gas in a molded resin. This method of manufacturing molded capacitors can be expected to cause a slight amount of insulating gas to remain in the uneven parts on both ends of the winding of the capacitor element, resulting in improved corona discharge characteristics compared to those in which the capacitor element is not filled with insulating gas. At the same time, it has the advantage of improving dielectric strength.

[Problems to be solved by the invention] However, in the method for manufacturing the molded capacitor described above, when embedding the capacitor element filled with insulating gas in the mold resin, there is a step in which the capacitor element is placed in the mold resin liquid. The insulating gas that had accumulated in the uneven parts on both ends of the winding of the capacitor element gains buoyancy from the molding resin liquid, and some of it flows out as bubbles in the molding resin liquid, and further hardens the molding resin liquid. When the reaction temperature is raised to proceed with the curing reaction, the remaining insulating gas is warmed and gains even greater buoyancy, forming bubbles in the molding resin liquid and further exiting, so that both ends of the winding of the capacitor element There is also the problem that it is difficult to expect that the insulating gas will remain in the uneven portions.

In addition, the phenomenon in which the SF ₆ gas filled during molding becomes bubbles in the mold resin liquid due to buoyancy and escapes to the outside is exacerbated as the curing temperature of the mold resin increases, and this phenomenon is important for improving corona discharge. There is a problem that it may have a negative impact.

Furthermore, the curing temperature of the mold resin (approximately 50℃~
There is a problem in that when the temperature is returned from 120°C to room temperature, the gas pressure of the insulating gas at the weak point in the dielectric strength decreases to below atmospheric pressure, which results in a decrease in the corona discharge starting voltage.

Furthermore, such a molded capacitor has the problem that when the ambient temperature becomes low, the gas pressure further decreases and the corona discharge starting voltage decreases, making it impossible to use it in cold regions.

Therefore, this invention aims to provide a molded capacitor that can improve the corona discharge characteristics by sealing insulating gas under positive pressure in the dielectric strength weak points around the edges of the metal thin film on both ends of the winding of a wound capacitor element. That is.

(b) Structure of the device [Means for solving the problem] In order to solve the above problem, this device has the following features:
The container and the cylinder pipe are communicated at the upper part, the wound capacitor element is housed in the container with separate gaps facing each end face, and the container and the cylinder pipe are filled with an insulating gas. At the same time, when molding the container and cylinder pipe with synthetic resin, the synthetic resin was flowed into the cylinder pipe to create a pressurized state, thereby sealing the insulating gas inside the container to a positive pressure state and molding them together.

[Function] When storing a capacitor element in a container, filling the container and cylinder pipe with insulating gas, and molding the container and cylinder pipe with synthetic resin, synthetic resin liquid is injected around the container and cylinder pipe. Then, first, the lower opening of the cylinder pipe is sealed with a synthetic resin liquid, so that the insulating gas can be sealed into the container and the cylinder pipe at the gas pressure at the time of filling the insulating gas.

Additionally, as more synthetic resin liquid is injected into the container and around the cylinder pipe, the gravity of the injected synthetic resin liquid is applied to the free surface of the synthetic resin liquid forming at the bottom of the cylinder pipe, creating a pressurized state. , it is possible to push up and flow the synthetic resin liquid upward into the cylinder pipe, thereby increasing the gas pressure of the insulating gas in the container.

Furthermore, after filling the container and cylinder pipe with synthetic resin liquid, if the synthetic resin liquid is further injected while being pressurized by an external force, the pressurized injection force is applied to the free surface of the synthetic resin liquid, resulting in an even greater pressurized state. As a result, the synthetic resin liquid enters while pushing the insulating gas upwards into the cylinder pipe against the compressive repulsive force of the insulating gas, and the insulating gas is compressed by the amount of synthetic resin liquid that has entered the cylinder pipe. The gas pressure of the insulating gas can be further increased.

When the gas pressure of the insulating gas in the container reaches a desired value, the insulating gas can be sealed in the container at a desired high pressure by reacting and curing the injected synthetic resin liquid while maintaining the pressurized state.

By sealing the insulating gas in the container at a desired high pressure, the corona discharge starting voltage at the weak point in the dielectric strength of the wound capacitor element can be increased according to Paschen's law. Starting voltage can be improved.

[Example] Hereinafter, the invention of the present application will be described as an example with reference to FIG.
This will be explained using FIGS. 2 and 3. In addition, Fig. 1 is a cross-sectional view of a molded capacitor explaining an example, Fig. 2 is a -' cross-sectional view of Fig. 1, and Fig. 3 is a cutout cross-section of a casting mold device used for manufacturing the molded capacitor. Show the diagram.

In the molded capacitor, a container 1 and a cylinder pipe 2 are connected at the upper part, and a wound capacitor element 5 is housed in the container 1 with separate gaps 7a and 7b facing both end surfaces 5a and 5b. and insulating gas, for example SF ₆ gas 8, in the container 1 and the cylinder pipe 2.
At the same time, when the container 1 and the cylinder pipe 2 are molded with a synthetic resin, for example, an epoxy resin 9, the epoxy resin 9 is flowed into the cylinder pipe 2 to create a pressurized state, thereby reducing the SF ₆ in the container 1. The gas 8 is sealed in a positive pressure state and is integrally molded.

The SF ₆ gas 8 can be sealed in a positive pressure state in the container 1 by the following method.

First, the container 1 and the cylinder pipe 2 communicate with each other at the upper part.
A wound type capacitor element 5 is positioned and housed in the container 1.

The container 1 consists of a container body 1a with an open bottom and a lid 1b sealed at the bottom.
Grommets 4a and 4b are provided in the cap 1a and the lid 1b to allow the lead wires 6a and 6b of the wound capacitor element 5 to be passed through and sealed by soldering.
Further, this container 1 has an inner diameter slightly larger than the outer diameter dimension of the wound capacitor element 5, and has both wound end surfaces 5a and 5b of the wound capacitor element 5 to be accommodated.
The inner vertical dimension is set to a height that forms gaps 7a and 7b facing each other.

After positioning and housing the wound capacitor element 5 in the container body 1a, the lid 1b is fixed in a sealed state, and the eyelets 4 of the container body 1a and the lid 1b are fixed.
Lead wires 6a and 6b are inserted into portions a and 4b and soldered to seal them.

Next, as shown in FIG. 3, this is set in a mold 10 having an inner diameter larger than its outer diameter, and valves 11, 13 and 14 are closed.
2 and operate the vacuum pump 15 to remove the mold 10.
Evacuate the inside.

The air in the container 1 is degassed through the cylinder pipe 2 from the communication part 3 with the cylinder pipe 2, and the air inside the container 1 and the cylinder pipe 2 are removed.
Pull the inside to a vacuum level of about 10 ^-2 mmHg.

Next, the valve 12 is closed and the valve 13 is opened to allow the SF ₆ gas 8 to flow into the vacuum mold 10 to fill the cylinder pipe 2 and the container 1 with the SF ₆ gas 8. An epoxy resin liquid is injected between the container 1 and the cylinder pipe 2.

The epoxy resin liquid 9' is made by mixing an epoxy resin with an inorganic filler and having a density ρ of 1.3 grams/
Use the one from cc. When this epoxy resin liquid 9' is injected between the mold 10, the container 1, and the cylinder pipe 2, the lower opening of the cylinder pipe 2 is first sealed with the epoxy resin liquid 9', and the container 1 and cylinder pipe 2 are sealed. SF ₆ gas 8 is sealed in the tube 2 . FIG. 3 depicts approximately this state. The sealing pressure of the SF ₆ gas 8 in this state is defined as P _p [Torr], and this sealing pressure P _p can be determined as appropriate. When the epoxy resin liquid 9' is further injected and the space between the mold 10, the container 1, and the cylinder pipe 2 is filled, the free surface of the synthetic resin liquid 9' formed in the lower part of the cylinder pipe 2 is filled. A pressurized state is created by adding the gravity of the injected synthetic resin liquid 9'.
Assuming that the height of the cylinder pipe is 12 cm, the gravity P _h applied to this free surface is P _h = ρgh = 15288 [dyn/cm ² ], and this gravity P _{h is} 8, the gas pressure P _x has increased from P _p to P _x = P _p + 0.015288 [Torr] and is balanced. In this pressurized state where the space between the mold 10, the container 1 and the cylinder pipe 2 is filled with the epoxy resin liquid 9',
Furthermore, when the epoxy resin liquid 9' is injected while being pressurized by an external force, a pressurized state is created in which the pressurizing force by the external force is further applied to the free surface, and as a result, SF ₆
While compressing the gas and pushing it inside, the epoxy resin liquid 9' enters into the upper direction of the cylinder pipe 2.
The SF ₆ gas 8 inside is compressed by the amount of epoxy resin liquid that has entered into the cylinder pipe 2, and therefore the SF ₆ gas 8 inside
The gas pressure P _x becomes a pressurized state that is further increased from P _p .

For example, the injection pressure of the epoxy resin liquid 9' is
Two types are set, 1.5×10 ⁶ dyn/cm ² and 2.0×10 ⁶ dyn/cm ² , and the internal volume of the cylinder pipe 2 is the value obtained by subtracting the volume of the wound capacitor element 5 from the internal volume of the container 1. When set to approximately equal values, the gas pressure P _x of SF ₆ gas in container 1 is approximately 1.4 (P _{p +0.015288} ) Torr and 1.9 (P _p +0.015288) from (P O +0.015288) Torr, respectively. It will rise to Torr.

In this way, the gas pressure of the SF ₆ gas 8 in the container 1 is increased to a desired value, and the injected synthetic resin liquid 9' is reacted and cured while maintaining the pressurized state.
SF ₆ gas 8 can be sealed in the container 1 at a desired high pressure. Thereafter, the capacitor is taken out from the mold 10 and subjected to post-processing if necessary to obtain the molded capacitor of this invention.

Gas pressure P _x of SF ₆ gas in container 1 is 1.015Torr,
Molded capacitors of this invention with three types of settings, 1.4 Torr and 1.9 Torr, were created, and the corona discharge start voltages for each were 1.2 times and 1.7 times higher than those of molded capacitors created using the conventional manufacturing method.
We were able to improve the value to 2.3 times higher.

(c) Effects of the invention The molded capacitor of this invention is capable of supplying an insulating gas into the container housing the wound capacitor element by injecting pressurized synthetic resin liquid for molding from the lower opening of the cylinder pipe. Since it is sealed under high pressure, it is possible to interpose insulating gas at a high density in the weak points of dielectric strength on both ends of the winding of the wound capacitor element, and it is possible to improve the corona discharge starting voltage. be.

[Brief explanation of the drawing]

Fig. 1 is an end view of a molded capacitor in an embodiment, Fig. 2 is a sectional view taken along -' of Fig. 1, and Fig.
The figure shows that it is a cutaway sectional view of the casting mold device. 1... Container, 2... Cylinder pipe, 3... Communication portion, 4
a, 4b...Each eyelet, 5...Wound type capacitor element, 5a, 5b...Each wound end face,
6a, 6b...Leader lines, 7a, 7b respectively
...Gap, 8... _SF6 gas, 9...Epoxy resin liquid, 10...Mold, 11, 12, 13,
14... each valve, 15... vacuum pump,
16...Synthetic resin liquid tank, 17... _SF6 gas cylinder.

Claims (1)

[Scope of utility model registration request] The container and the cylinder pipe are communicated at the upper part, the wound capacitor element is housed in the container with separate gaps facing each end face, and the container and the cylinder pipe are filled with an insulating gas. In addition, when molding the container and cylinder pipe with synthetic resin, the synthetic resin flows into the cylinder pipe to create a pressurized state, thereby sealing the insulating gas inside the container to a positive pressure state and molding them together. molded capacitor.