JPH01233717A - Manufacture of capacitor - Google Patents

Abstract

PURPOSE:To secure the stability of a capacitor for a long period, by inserting insulating films which are free from deterioration due to heat into intervals between an electrode tab and a dielectric film as well as an electrode foil located at the rear of the electrode tab and the dielectric film. CONSTITUTION:Dielectric films 1 and 1' as well as metallic foils 2 and 2' are wound in such a manner that they are combined for winding. Insulation- reinforcement sheets 5 and 5' having each width which is wider than that of each one of electrode tabs 4 and 4' are inserted into intervals between the tab 4 and the film 1 as well as the electrode foil of the rear of the tab 4' and the film 1'. Insulation films where no thermal deterioration takes place are used as the sheets 5 and 5'. The insulation films are protected from dielectric breakdown due to the rapid rise of a temperature in the electrode foil. Thus, the stability of a capacitor is secured for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a cylindrical high voltage capacitor wound in which the leads are drawn out in the same direction.

(Prior art) Conventionally, in manufacturing a wound cylindrical high voltage capacitor with leads drawn out in the same direction, (1) dielectric film - (2)
The combination of metal foil - (1) dielectric film - (2) metal foil is wound together, each metal foil is assembled as an electrode, and then impregnated with insulating oil etc. to produce high voltage and high charge. Although it was used as a discharge/current capacitor, if the electrode lead terminals (3) (3)' (hereinafter referred to as leads) are drawn out in the same direction, each metal foil (hereinafter referred to as
The lead is inserted into direct contact with the electrode foil (called an electrode foil), and the lead is pulled out by another overlapping metal piece, ie, an electrode tab. In this case, in order to prevent the insertion of the electrode tabs from adversely affecting the dielectric film, especially deterioration of the withstand voltage characteristics, the insulating reinforcing sheets (5) (5) are wider than the electrode tabs (4) (4)'. 'Electrode tab (4) (4)'?
It is practiced to insert the film between the ti body films (+) (+)'.

At this time, - For boat fishing, the reinforcing sheet should be electrode tabs (4) (4).
)' to alleviate the electrical stress caused by the physical discontinuity caused by the insertion of the dielectric film (1), which is much thicker than the dielectric film (1) The same type of film or insulating paper is used.

(Problem to be solved by the invention) The foil-type high-voltage capacitor manufactured by this method exhibits extremely stable operation when high voltage is continuously applied, and has a voltage lower than the dielectric breakdown voltage of the dielectric film. At the applied voltage,
Sudden short circuits are unlikely to occur.

However, on the other hand, if the same type of capacitor is repeatedly charged or discharged rapidly at an applied voltage considerably lower than the dielectric breakdown voltage of the dielectric film (7ti pressure), even if it has a reinforcing sheet, the electrode tabs In the inserted part, a reinforcing sheet (5) (5) that is considerably thicker than the dielectric film is used.
Insulation breakdown occurs at the insertion part of the electrode tab (4) (4) protected by ', or more specifically, at discontinuous and unstable points on the electrode tab surface, making it difficult to ensure long-term stability. .

Especially when the electrode foil is aluminum foil, there is no significant improvement even if the electrode tab is replaced with aluminum, copper, tin, or other metal foil, and the reinforcing sheet is 5 to 6 times as thick as the dielectric film. Even with regard to thickness, it is difficult to fundamentally prevent this dielectric breakdown.

(Means for Solving the Problems) The present invention focuses on the above-mentioned phenomena, conducts experiments to investigate the causes thereof, and provides means for solving these problems.

First, we discovered that this phenomenon causes large currents flowing during the operation of high-voltage capacitors, particularly at the rising and falling times of charging or discharging, to have a large effect on the dielectric breakdown of these capacitors.

In other words, in this type of capacitor, the wound element is impregnated with insulating oil τ, so the electrode tab and electrode foil appear to maintain sufficient electrical contact, but microscopically As can be seen, there was an extremely thin oil film between the 7u pole tab and the electrode, with only a few limited electrical contact points.

When these capacitors are rapidly charged or discharged, a large current momentarily flows from the electrode tab to the electrode foil or in the opposite direction.

This large current repeats the phenomenon in which the electrode foil at the limited contact points described above melts and scatters, and the current concentration point moves to other contact points. As a result, fine holes are formed in the melt-splattered areas of the electrode foil, and the number of holes increases in proportion to the number of times charging and discharging are repeated.

If we consider microscopically the moment when a hole is formed, the temperature of the electrode foil at the point where the current is concentrated becomes below its melting point, and as it scatters, sparks are generated, and the temperature rises along with the light.

As a result, the inserted protective film undergoes microscopic decomposition or deterioration due to light or heat, creating dangerous conditions for these capacitors such as carbonization or gas generation, which can lead to dielectric breakdown of this type of capacitor. .

In order to verify the above estimation, the following experiment was conducted to confirm its correctness.

Rated voltage 8KVD, C, capacitance 20μF.

M711 body film - polyethylene laphthalate thickness 26μm, ? fi pole foil Aluminum foil 5μm Insert 2 electrode tabs per electrode on one side, tab metal - copper foil 50
μm, impregnated with insulating oil.

All the operating procedures were the same, and the following 5 types of reinforcing sheets were selected, 5 of each type, for a total of 25 pieces.After completion, they were sequentially charged at loOmA from a high voltage power supply set to a DC voltage of 8KV. After the capacitor was fully charged, the picture electrode terminal of the capacitor was discharged through a 50Ω resistor.

The maximum current during discharge is 80 A, assuming that the electrode tabs of each capacitor operate under the same conditions.

This test was repeated continuously until the capacitor was destroyed, and the number of charging and discharging cycles was investigated. The results are as follows.

Type Reinforcement sheet Thickness Minimum to maximum number of times 5 times, average number μm
Times XNO, I!
Rie f lente phthalate 80 280~64
00 281ON0.2 j! J1
uEshi7 90 220-5400
300ONO, 3f rie flen 8
0 125-3800
198ONO, 4$' Riamidoimide 40
6800-13500 865O
NO, 5v squid paper 25 17800~
29500 19900 Furthermore, even when the same test was carried out by replacing the copper foil with tin foil or aluminum foil for the electrode tab, the results were largely the same and no change was observed.

In particular, we investigated the location where dielectric breakdown occurred in all of the NO, '5 groups and three in the N004 group, but as a result, we found that it was not the area around the electrode tab insertion, but the area around the element winding of the test capacitor. It turned out that this was due to wrinkles that occurred near the center of the element during the initial stage of the removal process.

From these results, it can be said that the effectiveness of a film that does not cause thermal deterioration as a reinforcing sheet has been proven.

(Function) In order to prevent dielectric breakdown during use in stone-shaped high voltage capacitors whose leads are pulled out in the same direction, we inserted an insulating reinforcing sheet that does not deteriorate due to heat and is wider than the electrode tab to increase its effectiveness. prove

(Example) Examples of the present invention will be described below.

The present invention improves the +i Insert the electrode tabs (4) (4)' and the wider insulation reinforcing sheets (5) (5)' between the electrode tabs and the dielectric film, and between the electrode foil and the dielectric filter on the back of the electrode tabs with a purpose. In this process, an insulating film that does not cause thermal deterioration is inserted as a material to protect the electrode foil from dielectric breakdown due to a rapid temperature rise caused by the rapid current of charging and discharging by a high-voltage capacitor, and to ensure long-term stability. The purpose is to maintain the

(Effects of the Invention) By inserting the insulating film that does not cause thermal deterioration according to the present invention between the electrode tab and the dielectric film, and between the electrode foil and the dielectric film on the back side of the electrode tab, rapid charging can be achieved. Its long-term stability is ensured against the dielectric breakdown of the stone-shaped high voltage capacitor due to the rapid rise in temperature of the electrode tab due to discharge.

Of course, as long as the insulating film to be inserted does not undergo thermal deterioration, it may be made of an inorganic film (e.g. mica paper) or a material that does not undergo thermal decomposition at high temperatures (
synthetic resin (e.g. polyamide-imide resin film, etc.)
, and will not be specified.

Furthermore, although this is a stone-shaped high-voltage capacitor whose leads are drawn out in the same direction, this method also ensures long-term stability from long-term dielectric breakdown in stone-shaped high-voltage capacitors whose leads extend in both directions. −

[Brief explanation of the drawing]

FIG. 1 is a developed view of the vicinity of the electrode tab insertion part of a stone-shaped high-voltage capacitor having a reinforcing sheet, and a diagram explaining the state of reinforcing and inserting the sheet. (1) (1)' is dielectric film (2) (2)' is metal foil (3) (3)' is electrode lead (4) (4)'
is the electrode tab (5) (5)' is the reinforcing sheet

Claims (1)

[Claims] In foil-type high voltage capacitors with leads pulled out in the same direction,
A method for manufacturing a wound high-voltage foil capacitor in which an insulating film that does not cause thermal deterioration is inserted as a reinforcing sheet at the insertion point of an electrode tab for lead extraction.