JPH04102072A - Dielectric characteristics measuring method of film - Google Patents

Abstract

PURPOSE:To enable a sample film to be fit easily and achieve an efficient measurement by forming a metal deposition film on a sample film and a protection film and by overlapping it for holding it among a high-voltage side electrode, a main electrode, and a guard electrode. CONSTITUTION:A high-voltage metal deposition film 53, a main metal deposition film 55, and a guard metal deposition film 56 opposing to a high-voltage side electrode 29, a main electrode 36, and a guard electrode 39 are formed on a sample film 51. On the other hand, a protection film 61 is made by the same material as that of the film 51 and has a circular hole 62 where the electrode 36 is fit. An annular protection metal deposition film 64 is formed opposing an outer-peripheral part of the deposition film 55 and the deposition film 56 on one surface of this circular hole 62. The film 61 is connected to a connection part 66 which is formed on the other surface of this deposition film 64. Then, other surfaces of the films 51 and 61 are overlapped so that each metal deposition film is in concentric shape and they are held among the electrodes 29, 36, and 39 while the electrode 36 is engaged to the circular hole 62 for measurement, thus enabling a sample film to be fit easily and measurement to be made efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the dielectric properties of a polymer film, particularly a film dielectric property measurement method that allows accurate and easy measurement of the dielectric properties of a thin film with a small area.

[Conventional technology]

Conventionally, the dielectric properties of a polymer film have been determined by a high-voltage side electrode 1 provided concentrically, a main electrode facing the high-voltage side electrode 1, and a guard electrode 3 surrounding the main electrode, as shown in FIGS. 1o and 11. Sample film 4 is attached to the three-terminal parallel plate electrode.
Measurements are made using a Schier Linda Brison in insulating oil.

However, as shown in FIG. 12, in this method, contact with the electrode surface is incomplete due to the bending and surface roughness of the sample film 4. In addition, in order to suppress the disturbance of the electric field at the periphery of the main electrode, the distance between the main electrode 2 and the guard electrode 3 must be smaller than the thickness of the sample film 4, but if the sample film 4 becomes thinner, the above distance should be made thinner than the sample film 4 As shown in FIG. 13, the electric field is disturbed between the main electrode 2 and the guard electrode 3, and the sample film 4
If the area cannot be made large, electric lines of force may occur on the creeping surface 5, making accurate measurement impossible.

As a solution to this problem, there is a three-terminal parallel plate electrode as shown in FIG. That is, an electrode film 6 corresponding to the high voltage side electrode 1, the main electrode 2, and the guard electrode 3 is provided on the sample film 4.
, 7.8 are formed by metal vapor deposition, this sample film 4 is fixed to an acrylic frame 9 by sandwiching and adhering it with fast-curing epoxy resin 10, and a lead wire 10 is attached to each electrode film 6, 7.8 using a silver base plate. At the same time, the entire inside of the acrylic frame 9 is molded with epoxy resin 12, which hardens at room temperature, to prevent partial discharges and to maintain tan resistance up to high electric fields.
This made it possible to measure δ.

In general, in a three-terminal electrode system, the guard electrode 3 (electrode film 8) suppresses the disturbance of the electric field at the periphery of the main electrode 2 (electrode film 7), and also serves to connect the main electrode 2 and the high voltage side electrode 1 (electrode film 6). Of the current flowing during this period, only the component flowing inside the sample film is measured, excluding the surface current component flowing on the surface of the sample film 4. In order to suppress the disturbance of the electric field at the periphery of the main electrode 2, the distance between the guard electrode 3 and the main electrode 2 must be made smaller than the thickness of the sample film 4. However, when a thin sample film 4 is to be used, It is difficult to ensure electrical insulation by reducing the spacing and making the impedance between them larger than the input impedance of the measuring device, and the spacing is usually 2 to 3 mm.

Therefore, in such an electrode system, disturbances in the electric field occur near the periphery of the main electrode 2. Therefore, when tan δ is measured in a high-temperature region using the sample film 4 molded with epoxy resin 12, depending on the conditions, the tan δ of the surrounding epoxy resin 12 may show a larger value, which may cause the tan δ of the sample film 4 to be larger. It has been found that there are cases where the measured values are affected.

Therefore, as shown in FIG. 15, a guard film 13 made of the same material as the sample film 4 is brought into close contact with the main electrode 2 side, and metal is deposited on top of the guard film 13 to form a metal deposited film corresponding to the guard electrode 3. 14 covers the main electrode 2. With this improved structure, it was possible to reduce the disturbance of the lines of electric force at the periphery of the main electrode 2 and to prevent the lines of electric force from penetrating into the epoxy resin 12.

[Problem to be solved by the invention]

However, in the electrode system with the above improved structure,
It takes time and manpower to form the metal vapor deposited film that will become the high-voltage side electrode, main electrode, and guard electrode on the sample film.In particular, in order to harden the epoxy resin used for molding, pour the epoxy resin on one side and wait until after it has hardened. , molding is done by pouring epoxy resin on the other side and curing it, or it takes more than 7 days to cure the epoxy resin 12 on each side, so it takes more than 2 weeks for both, which is an extremely inefficient process. It becomes.

In view of the above circumstances, the present inventors have conducted extensive research to develop a method for measuring the dielectric properties of films that can be carried out efficiently and easily. It was thought that if the sample film was removably sandwiched between the high-voltage side electrode and the main electrode and guard electrode facing the high-voltage side electrode, the accuracy of the above measurement method would be maintained and the operation would be much easier.

The present invention has been made based on the above idea, and an object of the present invention is to provide a method for measuring the dielectric properties of a film, which allows a sample film to be easily mounted and efficiently measured.

[Means to solve the problem]

In order to achieve the above object, the method for measuring the dielectric properties of a film according to the present invention includes, as an electrode system, a high voltage side electrode, a main electrode provided opposite to this, and an annular guard electrode surrounding this. A method for measuring the dielectric properties of a film using concentric three-terminal parallel plate electrodes, in which a high-voltage metal vapor-deposited film facing the high-voltage side electrode is formed on one surface, a main metal vapor-deposited film facing the main electrode on the other surface, and A sample film on which a guard metal vapor deposited film is formed facing the guard electrode, and a circular hole made of the same material as the sample film, into which the main electrode fits, and one surface around the circular hole has a is a protective film in which a ring-shaped protective metal vapor deposited film is formed facing the outer periphery of the main metal vapor deposited film and the guard metal vapor deposited film, and this protective metal vapor deposited film is connected to a connection portion formed on the other surface. , overlap the other side of the sample film and the other side of the protective film so that each metal vapor deposited film is concentric, and with the main electrode fitted into the circular hole of the protective film, insert the high voltage electrode , the main electrode, and the guard electrode. Measurements are usually carried out in insulating oil.

[Effect]

Since the method of the present invention has the above-mentioned configuration, a metal vapor deposition film is formed on the sample film and the protective film separately, and these are overlapped and crimped to form a high-voltage side electrode that can be freely separated, a main electrode and By sandwiching it between the guard electrode and the guard electrode, accurate measurement becomes possible.

〔Example〕

1 to 3 show an embodiment of a concentric three-terminal parallel plate electrode used in the measuring method of the present invention, and reference numerals 21 and 22 in the figures represent a base and a lower stand made of Bakelite, respectively. The screws on both sides of the two Teflon columns 23 are inserted into these upper and lower stands 21 and 22, and the base legs 24
, a lower stand ¥25 is screwed together and fixed in a frame shape.

A high voltage side electrode support 26 made of Teflon is screwed into the center of the upper stand 21, and a support stopper 27 is screwed to the lower end thereof. This electrode support 26 has a mouth.

The opening of the high-voltage side electrode 29 made of stainless steel, which is mounted perpendicular to the center of the electrode 28, is inserted through the opening of the electrode 29.

A spring 30 is attached to the rod 28 to bias the high voltage side electrode 29 downward. Further, a female thread 20 is provided on the side of the electrode support 26 to lock the sliding movement of the rod 28, and a terminal ring 32 made of stainless steel is attached to the upper part of the opening and door 28. The periphery of the high-voltage side electrode 29 is formed to be smaller in the downward and inward direction, and the lower surface is the same as that of the high-voltage side electrode 29.
The contact portion 29a has a smaller diameter than the upper portion of the contact portion 9, thereby suppressing the generation of electric lines of force along the creeping surface.

Further, a main electrode support 33 made of Teflon is fixed to the center of the lower stand 22 with a screw 34, and a main electrode made of stainless steel with a port 35 attached at right angles to the center of the main electrode support 33. 36 is attached by inserting the rod 35 mentioned above. A terminal screw 37 is provided at the lower end of the rod 35.

Further, a cylindrical Teflon guard electrode support 38 is provided surrounding the main electrode support 33. Fitted between the guard electrode support 38 and the main electrode support 33 is the cylindrical part 40 of a guard electrode 39 made of stainless steel, which has a cylindrical part 40 at the bottom and is open at a right angle at the tip. At the same time, the lower surface of the guard electrode 39 portion opened at right angles is supported by the card electrode holder 38 via an O-ring.

A lead wire 42 is attached to the cylindrical portion 40 .

4 and 5 show a sample film 51 used in the measuring method of the present invention, which has a small area (for example, 40
*40mm).

One surface 52 of this sample film is provided with a high-pressure metal vapor deposited film 53 facing the high voltage side electrode 29, and the other surface 54 is provided with a main metal vapor deposited film facing the main electrode 36 and guard electrode 39. 55, and a guard metal vapor deposited film 56 facing the guard electrode 39.

6 and 7 show a protective film 61, which is of the same quality as the sample film 51 and has four parts of the sample film 51.
It has about twice the area. A hole 62 slightly larger than the main electrode 36 into which the main electrode 36 fits is provided in the center of the protective film 61 .

On one side 63 of the protective film 61 around the hole 62, an annular protective metal vapor deposited film 64 is formed which faces the outer peripheral portion of the main metal vapor deposited film 55 and the guard metal vapor deposited film 56. This protective metal vapor deposition film 64 is connected to a connecting portion 66 on the other surface 65. Gold is used in all of the above metal vapor deposition films. The diameters of each electrode and each metal vapor deposited film mentioned above are indicated by the following symbols.

Inner diameter of guard electrode 39: Dgi Outer diameter of card electrode 39: Dgo Diameter of main electrode 36, Dm Contact portion diameter of high voltage side electrode 29 Dh Inner diameter of card metal vapor deposition film 56: dgi Outer diameter/dg of guard metal vapor deposited film 56.

Diameter of main metal vapor deposited film 55, dm Diameter of high-pressure metal vapor deposition film 53 dh Inner diameter of protective metal vapor deposited film 64: dpi Outer diameter of the protective metal vapor deposited film 64 clp.

The following relationship holds between these.

Main electrode side Dm<Dg i<dm<dg i<Dgo<dg.

High pressure side Dh<dp.

Protective film Dm<dp i<dm To measure the dielectric properties of the sample film using the above concentric three-terminal parallel plate electrode, sample film, and protective film, the other surface 54 of the sample film 51 and the protective film 61
The other surfaces 65 of the metal evaporated films are placed concentrically.

Lift the high voltage side electrode 29 against the spring 30, fit the main electrode 36 into the hole 62 as shown in FIG. It is sandwiched in between and is usually immersed in insulating oil.

When measured in this manner, as shown in Figure 9, the lines of electric force at the peripheral edge of the main electrode 36 are formed from the high-voltage side electrode 29 toward the main electrode 36 without any disturbance, and are accurate without generating noise. dielectric property values can be obtained.

Example 1 Thickness] 40 mm x 40 mm polyethylene and polypropylene films were used as sample films, and the same 80 mm x 80 mm films were used as protective films. The tan δ was measured at 50 Hz and various voltages.

Comparative Example 1 Using the method shown in Figures 10 and 11, a sample film was prepared with a thickness of 100 μm, 40 mm x 40 mm, and a diameter of 90 mm.
The tan δ was measured using polyethylene and polypropylene films of 1.0 mm in diameter at room temperature at a frequency of 50) 1z and varying the voltage.

The results of Example 1 and Comparative Example 1 are summarized in Table 1.

Table 1 However, the × in the table is due to noise.

Indicates something that cannot be balanced.

[Effects of the Invention] As explained above, the method for measuring dielectric properties of a film according to the present invention involves forming a metal vapor deposition film separately on a sample film and a protective film, and then superimposing them without molding an epoxy resin. By sandwiching the high-voltage electrode between the main electrode and the guard electrode, which can be freely spaced and brought into close contact with each other, it has the advantage that high voltage can be used for accurate and efficient measurement.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an example of a concentric three-terminal parallel plate electrode used in the method of the present invention, and FIG.
The -■ line asymmetrical diagram, FIG. 3 is the I[[-1 line asymmetrical diagram of FIG. Figure 5 shows the other side, Figures 6 and 7 are plan views of the protective film, and Figure 6 shows one side.
Figure 7 is a diagram showing the other side, Figure 8 is a diagram showing the concentric three-terminal parallel plate electrode of Figure 1 with a sample film and a protective film stacked on top of each other, and Figure 9 is a diagram showing the main electrode periphery. Figures 10 and 11, which show electric lines of force, show an example of the conventional method. Figure 10 is a plan view, and Figure 11 is a diagram showing the
Fig. 12 and 13 are views showing the drawbacks of the method shown in Figs. FIG. 15, an explanatory diagram of the conventional method, is an explanatory diagram of a further improved conventional method. 1... High voltage side electrode, 2... Main electrode, 3... Guard electrode, 4... Sample film, 5... Creeping surface, 6... Electrode film (equivalent to high voltage side electrode), 7... Electrode Membrane (equivalent to main electrode),
8 electrode film (equivalent to guard electrode), 9. Acrylic frame, 10.
・Fast-curing epoxy resin, 1 Toread wire, 12... Epoxy resin that hardens at room temperature, 13 ・Card film, 14
・・Metal deposition film covering the main electrode (equivalent to guard electrode), 21
・・Upper stand, 22・Lower stand, 23・Column, 24 Upper stand foot, 2
5. Lower stand foot, 26.. High voltage side electrode support, 27.. Support stop, 28.. o throat, 29. High voltage side electrode, 29a..
Contact part, 30...No/No, 31 Set screw, 32...
Terminal ring, 33・Main electrode support, 34・Screw, 35・
Mouth, C, 36・Main electrode, 37 Terminal screw, 38・Guard electrode support, 39 Cart electrode, 40−・Lower cylinder part, 41
・0 ring, 51 ・Sample film, 52 One side, 53
- High pressure metal vapor deposition film, 54 - Other surface, 55 - Main metal vapor deposition film, 56 Guard metal vapor deposition film, 61 - Protective film,
62 Hole, 63・One side, 64 Protective metal vapor deposited film, 6
5 Other side, 66 Connection.

Claims (2)

[Claims] (1) A method for measuring dielectric properties of a film using a concentric three-terminal parallel plate electrode consisting of a high-voltage side electrode, a main electrode provided opposite to the high-voltage side electrode, and an annular guard electrode surrounding the high-voltage side electrode. , a high-pressure metal vapor-deposited film facing the high-voltage side electrode on one side;
A sample film is formed of the same material as the sample film, and has a main metal vapor deposited film facing the main electrode and a guard metal vapor deposit film opposing the guard electrode formed on the other surface, and the main electrode is fitted into the sample film. It has a circular hole, and on one side around the circular hole, a ring-shaped protective metal vapor deposited film is formed that faces the outer periphery of the main metal vapor deposited film and the guard metal vapor deposited film. Using the connecting portion formed on the surface and the connected protective film, overlap the other surface of the sample film and the other surface of the protective film so that each metal vapor deposited film is concentric, and then 1. A method for measuring dielectric properties of a film, which comprises sandwiching the main electrode between the high-voltage electrode and a main electrode and a guard electrode in a state where the main electrode is fitted into a circular hole in the film. (2) The method for measuring dielectric properties of a film according to claim (1), wherein the measurement is carried out in insulating oil.