SU799029A1 - Standard electric design capacitor - Google Patents

Description

one

This invention relates to metrology and can be used as a farad standard.

A reference capacitor is known, consisting of four parallel ones. electrodes, the capacity of which is determined by its length l.

However, such a capacitor, due to the inability to control the location of the electrodes, does not provide the required accuracy.

The closest to the proposed technical essence and the achieved result is a flat capacitor with a guard electrode, the capacity of which is determined, in particular, by the area of its electrodes.

However, its area cannot be measured with the required accuracy, and therefore such a capacitor is not used as a reference.

The purpose of the invention is to improve the accuracy in the proposed reference electrical capacitor of fixed capacitance.

The goal is achieved by the fact that in a capacitor containing two flat parallel electrodes, one; of which is surrounded by a guard electrode, the electrodes are divided into symmetric sections by straight dielectric gaps, made in the form of squares and divided into four symmetric sections by two mutually perpendicular dielectric gaps, and the electrode surrounded by the guard electrode is divided by dielectric gaps along the diagonal, and the other electrode is gaps parallel to its sides.

In addition, the electrodes are divided into four symmetrical sections of two

5 mutually perpendicular dielectric gaps, the electrode surrounded by the guard electrode being square and divided by dielectric gaps located parallel to its sides.

FIG. 1 shows the electrodes of the proposed capacitor (without shield and cable entries); in fig. 2 is the same cross section.

five

The capacitor electrodes are quartz plates with metallized internal surfaces, interferometer mirrors. Electrodes 1-4 are limited by gaps, which are

0 by the sides and diagonals of the rectangle, and surrounded by a guard electrode 5 Electrodes 6–9 are limited by gaps H and M. All electrodes are placed in a screen 10 with windows 11 for passing an interferometer beam and provided with cable entries 12. The lower electrode is located on devices 13 for its movement during alignment. The capacitor is evacuated, its capacitances are measured by alternately connecting the electrodes into the equipment, which is presented in the table. The electrodes not connected with this measurement, the guard electrode 5, the shield 10 and the cable shields are grounded.

Table

The calculated value of the capacitance C is determined by the expression

 ., H (| T - 1-.

 C -.-T, C - 0.5 (, - C.,)

-o 5

.

(l-vit f)

G - -1 11 p.

/; - l (-f.Tc- | -) e «3. .

 WITH

d is the distance between the upper and

lower electrodes, measured with a high accuracy by the interference method; p, the dimensions of the sides of the rectangle bounding the electrodes 1, 2; 3/4, measured as dashed length measures with an accuracy that is several orders of magnitude smaller than the measurement accuracy d depending on the P / d ratio (or q / d), presented in table 2.

table 2

To eliminate the SPHIG screen. 2) it is necessary to enforce the inequality (2)

.. (5-6) d, (2) where 2 h is the size of the guard electrode 5.

Combining the electrodes with the interferometer mirrors makes it possible to control the location of the electrodes, and dividing them into sections with straight gaps reduces the required accuracy of measuring the electrode area (1–4) by several orders of magnitude.

Claims (3)

1. The reference electrical design capacitor of a constant capacitance, containing two Plr parallel electrodes, one of which is surrounded by a protective electrode, is so that, in order to improve the accuracy, the electrodes are divided into symmetrical sections linear dielectric gaps. 2. A capacitor in accordance with claim 1, wherein the electrodes are made in the form of squares and are divided into four symmetrical sections by two mutually perpendicular dielectric gaps, and the electrode surrounded by the guard electrode is divided by dielectric gaps diagonally, and the other electrode - gaps located parallel to its sides. 3. The capacitor according to claim 1, from which the electrodes are divided into four symmetrical sections by two mutually perpendicular dielectric gaps, wherein the electrode surrounded by the guard electrode is made in the form of a circle, and the other electrode is in the form of a square and divided by dielectric gaps parallel to its sides. Sources of information taken into account in the examination 1. USSR Author's Certificate No. 209590, cl. H 01 G 4/36, 03.11.66. .2.Eme F. Dielectric measurements. M., Himi, 1967, p.68 (prototype / // /// / // f // ff 4