SU1744628A1 - Method for determining resistance of film and sheet materials to action of partial discharges - Google Patents

Abstract

The measurement is used by materials. Essentially a cell with an arrangement of 2, and a small scissor in a dielectric, to the devices of a partial circuit, the inclusion S 1 il.

Use: relates to the instrumentation technique and can be used to determine the resistance of materials to partial discharges. SUMMARY OF THE INVENTION: The test cell contains test sample 1 located on a dielectric substrate 2 formed with an opening 3. The needle electrode 4 is located in a dielectric capillary 5, the end of which is dipped into a drop of a liquid dielectric, 6. Dielectric substrate 2 fits tightly to the flat electrode 7 With the help of the device 8, the intensity of partial discharges is recorded, and with the help of the trigger circuit 9, the installation triggers a non-shutdown when the test sample is broken. S 1 Il. h-

Description

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  About Yu SO

The invention relates to a measurement technique, can be used to determine the resistance of materials to partial discharges.

The purpose of the invention is to improve the accuracy of determining the specific rate of destruction of film and sheet materials to the action of partial discharges, expanding the scope of application of the method by studying dielectric, semiconductor and conductor materials.

The goal is achieved by the fact that in the electrode system the needle-needle electrode plane is placed in a dielectric capillary, the end of which is placed in a drop of liquid dielectric on the surface of the test sample. In this case, the sample under study is placed on a dielectric substrate, which w. Fits adjacent to a flat slider / and is made with a hole with a diameter D coaxially located with the needle electrode. the current density of the partial bits Jncn and determine the specific destruction rate by the expression

v dxm

Vp--, I)

TK JHCM

(de dx is the sample thickness;

rx is the lifetime of the test sample;

Jncn - measured intensity of partial bits.

The drawing shows a test cell.

The test cell contains the test piece 1, located on a dielectric substrate 2, made with hole 3, the Needle Electrode 4 is located: with a dielectric capillary 5, the s oroporo train is trimmed into a drop of liquid dielectric 6. Dielectric substrate 2 is tight to the flat electrode 7, with a decrease until 8 resolves the intensity of the partial discharges, and with the help of a trigger. - Scheme 9, the installation is triggered on disconnection during the breakdown of the test sample.

The dielectric substrate 2 is filled with a PM-1 polyimide film with a thickness of d 40 μm. The maximum diameter of the hole 3, no more than 3 mm, is limited by the fact that when the operating voltage is applied to the measuring electrodes 4, 7 due to the deformation of the studied film of sample 1 under the action of induced charges, as well as under the action of the capillary 5 and the liquid drops

dielectric 6 in some cases it is possible to short the electrode system.

The method consists in placing test sample 1 on a dielectric substrate 2. A needle electrode 4 is inserted into a dielectric capillary 5 and placed coaxially with a hole 3 in the dielectric substrate 2. The end of the dielectric capillary in the contact area with the test sample is placed in a drop of liquid dielectric (transformer oil) 6 with a volume of not more than 5 mm3. With large volumes of droplets, the liquid dielectric spreads over the surface of the sample under study. The measuring electrodes 4, 7 apply the test voltage Wisp, the value of which is chosen from the condition

EPR -dx Uicn Ek I. where Ek is the intensity of the electric field at which corona discharges occur;

I is the distance between the needle electrode and the test sample;

EPR short-term electrical

test specimen strength; dx is the sample thickness. With the help of a dielectric capillary, the end of which is placed in the Chaple of a liquid dielectric, the region of

corona discharge, which leads to a decrease in the intensity of the effect on the rate of corrosion and on the life span of the sliding gaps on the surface of the test material. Partial intensity

Juan bits are measured using block 8, the lifetime gx is by means of trigger points 9. The accuracy of recording the lifetime of the test sample is increased not only due to the fact that the electrode

placed in the dielectric capillary, but also due to the fact that the installation response current increases during the breakdown of the test sample, since the dielectric substrate is filled with a hole.

The specific destruction rate of the image is determined from the expression (1).

The accuracy of the registration of the lifetime is to increase the accuracy of determining the specific erosion rate of materials under

the action of partial bits Vp,

The following materials were tested: polyimide, polyethylene, fluoroplastic, combined / polyimodofluoroplastic films, polymide

5 films with semiconducting coatings, aluminum foil.

The distance from the needle electrode to the test specimen when tested is used (m x mm from 1 to 4 mm. With an increase in the distance I, the specific destruction rate of the material of the tested specimens Vp decreases.

The test results for some materials when tested at a distance of 1 mm in 1 mm with a dielectric substrate thickness d 40 mm are shown in the table.

The method for determining the specific destruction rate of film and sheet materials allows to expand the range of materials under investigation, i.e. dielectrics, semiconductors and conductors can be tested.

The application of the method for the comparative assessment of the resistance of some polymer films of polyethylene, polyimide, and fluoroplastic allows determining the optimal insulation design for the stator windings of electric machines operating under the conditions of the surface corona.

In addition, it is possible to more accurately determine the rate of destruction of materials under the action of partial discharges, since the dispersion of the values of Vp is reduced as compared with the method of the prototype.

Claims (2)

1. The method for determining the xyxsty of film and sheet materials to the action of partial discharges, based on measuring the lifetime of samples and the intensity of partial discharges in an electrode system of a needle-plane when the test sample is placed on a dielectric the substrate near the needle electrode, which is due to the fact that, in order to improve accuracy, the needle electrode is placed in a dielectric capillary, the end of which is immersed in a drop of a liquid dielectric on the surface of the test sample and pressed tightly to the latter, then the test voltage Kisp, the value of which is chosen from the condition Enp dx sUcn Ek-I, where Ek is the intensity of the electric field at which corona discharges occur; I is the distance between the needle electrode and the test sample; EPr - short-term electrical strength of the test sample; dx is the thickness of the test sample, record the sample lifetime gx and the intensity of the partial discharges JMcn and determine the specific destruction rate of the sample Vp from the expression V - dx fx Lisp 2. The method according to claim 1, characterized in that, in order to expand the scope of application of the method by providing tested. dielectric, semiconductor and conductive materials, the dielectric substrate is made with a thickness of not more than 40 microns.