SU1061067A1 - Variable value angle of loss tangent measure - Google Patents

Abstract

TANGENS MEASURE ANGLE LOSS. VARIABLE VALUE, containing a series-connected resistor and a first variable capacitor arranged in a shielding housing, a second alternating condenser-pp connected in parallel with them, differentially connected to the first, and a third capacitor connected between the shielding housing and the common connection terminal of the resistor and the first condenser the fact that, in order to increase accuracy and expand the range of linearity of reproducible quantities, the third capacitor is variable and the differential About the first capacitor, and the measure is equipped with a T-shaped circuit containing two connected between the terminals of the measure of series-connected capacitors and ns-circuit, included Hi o between the shielding housing and the middle connection terminal of these capacitors, g

Description

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The invention relates to electrical measuring equipment and can be used as an exemplary measure of the loss tangent (tgS).

A known measure tgS is a variable, and in which a capacitor is used as an adjustable element, and the total capacitance at the terminals of the measure remains unchanged 1.

The disadvantage of the measure is the quadratic nature of the scale and the presence of the initial value tgS,

A measure of the tangent of the loss angle of a variable value is also known, in which the scale is close to linear. In this measure, a capacitor is used as an adjustable element, and the total capacitance at the terminals of the measure remains unchanged. The known measure comprises a series-connected resistor and a first variable capacitor, connected in parallel to the screen, a second variable capacitor differentially connected to the first one, and a third capacitor connected between the screening box and the common connection terminal of the resistor and the first capacitor. The value of tgg at the terminals of the measure depends on the capacity of the first variable capacitor 2.

The disadvantages of the known measure are that the accuracy at the end of the scale is reduced and the range of reproducible values is limited.

The decrease in accuracy is associated with a violation of linearity at the end of the scale. It is revealed when considering a formula expressing the dependence tg b. measures on capacitance C j of the first variable capacitor

: 1h “oh,

WITH.

, 1 C + Cj

where (C, + C) is the main capacity of the measure (the magnitude is constant),

 const.

The aim of the invention is to improve the accuracy and expand the range of linearity of reproducible values,

This goal is achieved by the fact that, in a measure of the loss tangent of a variable value, containing a series-connected resistor placed in a shielding housing and a first variable capacitor connected in parallel with a second variable condenser differentially connected to the first, and a third capacitor connected between the shielding the case and the common output of the connection of the resistor and the first capacitor, the third capacitor is made variable and connected differentially with the first capacitor, and measure 5 is equipped with a T-shaped This circuit contains two capacitors connected in series between the terminals of a measure and an EC circuit connected between the shield case and the middle terminal of the connection of these capacitors.

The implementation of a third-capacitor variable and its differential inclusion with the first allows for obtaining a linear scale of loss angle tangent, which improves the accuracy of the measure. The introduction of a T-shaped circuit provides compensation for the initial tangent of the loss angle of the measure and thereby expands the range of reproducible values.

The drawing shows an electrical diagram of the measure.

Measure consists of consistently

5 connected resistors 1 and a variable capacitor 2 connected between pins 3 and 4, a variable capacitor 5 connected in parallel with this circuit, and a variable capacitor 6 connected between the shield housing 7 and the common output of resistor 1 and capacitor 2. Condensers 5 and 6 cc are differential with capacitor 2. Between pins 3 and 4 and housing 7 is on

 A T-shaped circuit containing two series-connected capacitors 8 and 9 and an RC circuit from resistor 10 and trimmer capacitor 11. The measure works as follows.

0 When certifying the measure, the capacitor 2 is set to the zero point of the scale and the zero value of the loss tangent of the measure is adjusted with the help of the capacitor 11. When used as a means of verification, the measure is attached to the bridge being tested and the capacitor 2 is changed, differential related capacitance

0 with it capacitors 5 and 6 that

allows to obtain linear increments of the loss angle tangent at a constant eiflKOCTH on pins 3 and 4. The loss tangent of the described

5 measures when tgS 6 0,1 is described by the formula

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€ “: ts; b: y; A 7

and Rrt is the resistance of the resistor R moat 1 and 10} C.-С, is the capacitance of capacitors 2,5,6,8,9 and 11, respectively

.

The first term of the formula is the main one and depends only on the capacitance C f, since, due to the differential connection of the capacitors 2 and 6, the total capacitance (C + C) remains constant. This allows to obtain a linear dependence of the loss tangent on the capacitance Cf, which provides an increase in accuracy

H - -. ,

The second term of the formula characterizes the negative losses introduced by the T-shaped circuit from the resistor | 10 and the capacitors 8,9 and 11. Egi. Losses can compensate for I the initial loss tangent and

thereby expanding the range of reproducible values in the direction of smaller values by approximately two orders of magnitude. Compensation is carried out by changing the capacitance C. In order for this change not to affect the constancy of the capacitance at the terminals of the measure, the capacitance of one of the capacitors 8 or 9 (C or C) is chosen much smaller than the capacitance ().

0

The proposed technical solution provides an increase in accuracy as a result of elimination of the error due to non-linearity of the scale; it has an expansion by two orders of magnitude and frequency ranges.

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Claims (1)

· Ί 54) ~ MEASURE OF THE TANGENT ANGLE FOR LOSS. A VARIABLE VALUE comprising a resistor and a first alternating capacitor located in a shielding case, a second alternating capacitor connected in parallel thereto, differentially connected to the first, and a third capacitor connected between the shielding case and the common connection terminal of the resistor and the first capacitor, characterized in that, in order to improve the accuracy and expand the range of linearity of reproducible quantities, the third capacitor is made variable and is switched on differentially with the first capacitor, and the measure is equipped with a T-shaped circuit containing two connected capacitors between the terminals of the series capacitor and an RC circuit connected between the shielding housing and the middle connection terminal of these capacitors.