SU1576877A1 - Apparatus for measuring tensit yo fariable magnetic field - Google Patents

Abstract

The invention relates to the field of magnetic measurements and can be used to measure the strength of a non-uniform magnetic field in a wide frequency range. The aim of the invention is to improve the measurement accuracy. A device for measuring the voltage of an alternating magnetic field contains a two-section induction converter from sections 1-1, 1-2 and 2, whose magnetic axes are parallel, aperiodic links 3,4,5 and 6 of the first order with the corresponding time constants, adder 7 and block 8 representation of information. Improving the measurement accuracy is achieved by changing the distance between the axes of the inductor coils. 4 il.

Description

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FIG. one

31576877

This invention relates to magnetic

ny

measurements are intended to measure the intensity (magnetic induction) of a non-uniform magnetic field in a wide frequency range.

The purpose of the invention is to improve the measurement accuracy.

Figure 1 shows the functional diagram of the device; figure 2 - amplitude-frequency characteristics of individual units; FIG. 3 is a wiring diagram of sections of a two-section induction converter;

and it has a slope, rational to frequency

4 shows the construction of a two-section nitration induction 3)

th information converter.

The device (Fig. 1) contains a two-section induction converter from sections 1 and 2. The magnetic axes are parallel, aperiodic links 3-6 of the first order with time constant respectively T5, T4, T, T, adder 7 and block 8 of information . The low frequency section consists of one coil containing two series and according to included concentric windings 1-1 and 1-2 with parallel axes. The high-frequency section consists of several (in FIG. 2, three 2-1.2-2 and 2TZ) coils evenly spaced along a cylindrical generatrix in the gap between the two windings 1-1 and J-2 of the coil section 1.

The device works as follows.

A sectioned induction transducer is placed in a measured alternating magnetic field with induction Btc. Each section of the converter with its aperiodic links converts the induction Vi into a variable electric voltage proportional to it in its specific frequency range, which goes to the adder 7 to sum the analog signals and then feed them to the block 8.

The slope of the amplitude-frequency characteristic (AFC) of the first branch of the device, consisting of windings 1-1, 1-2 and links 3 and 5, in the range from 1 to 2 (figure 2, a) is determined

The characteristics of section 1, the output voltage of which is proportional to the frequency of the measured induction BU. In the frequency range to - characteristics of stars 20

25

thirty

The slope of the frequency response of the second cabbage of the coils 2-1, niev 4 and 6, in range 1

to determine

- (figure 2, b) H

the characteristics of section 2, whose understanding is proportional to CO. In the range of h

one

- star characteristics

T4

read frequency frequency

from frequency --- to x

T4-branch begins to influence

in view of what

1 1 no frequencies - - - h

T4 TЈJ sima. Start from -

branch characteristic n 35 link 6 and it has a proportional hour

In the case of 40 sections of coils, captured by the actual frequency C0 (the section is located in the working frequency of section 2), the forward 45 th frequency response (figure 2, b - pu causes this device (figure 2, in nor).

In order to reduce 50 between sections when underfloor, an increase between sections is required. to ensure the absence of non-uniformity of the frequency response of the 55 frequency zone when measuring the magnetic field. inhomogeneous magnetic increase

Niv 3 and 5 can be considered frequency-independent. Starting with

frequency --- T3

The link 3 begins to affect the branch characteristic, and therefore the branch characteristic in the frequency range from

1T

before - frequency independent. Beginning

5 I from the frequency - (and higher) on the characteristics of the branch begins to influence the link 5

and it has a slope, inversely proportional to the frequency to (measured by

five

0

The slope of the frequency response of the second branch, consisting of coils 2-1, 2-2, 2-3 and links 4 and 6, in the frequency range up to 1

determined by the

- (figure 2, b) H

The characteristics of section 2, the output voltage of which is proportional to the frequency of CO. In the frequency range to

one ,

- characteristics of links 4 and 6 can

T4

considered frequency-independent. Start

from frequency --- to characteristic

The T4 branches start to influence link 4,

in view of which the characteristic in the frequency range 1 1 is not frequency - - - frequency independent

T4 TЈJ sima. Starting from - (and above) link 6 begins to influence the branch characteristic and it has a slope inversely proportional to frequency 6).

Providing Ti T5 we will get the total -, - the frequency response of the measuring instrument (figure 2, c) In case of mutual influence of the coil sections, the rise of the frequency response due to the resonance frequency C0 (section 1 ((0, can be located in the working frequency range) section 2) leads to an increase in the frequency response (figure 2, b - dashed line), this causes a rise in the frequency response of the entire device (figure 2, c, dotted line).

To reduce the magnetic coupling between the sections, all other things being equal, an increase in the distance between the sections is required. This makes it possible to ensure that there is no error due to uneven frequency response in a wide range of frequencies when measuring a uniform magnetic field. But when measuring inhomogeneous magnetic fields, the usual increase in the distance between sec5

This leads to the fact that the magnetic center of the converter is located in different points of space for different, measurement values of induction B. In this case, only a change in the distance between sections 1 and 2 reduces the error due to the non-uniformity of the magnetic field, and the decrease in this distance leads to an increase in the unevenness of the frequency response due to the mutual influence of the sections. In the proposed device, the magnetic fields of the windings of the low-frequency section at the location of the coils of the high-frequency section are in the opposite direction, which can always be ensured by choosing a4 and a2 (Fig.4) so that the total tray penetrating the carcass of the high-frequency section due to the magnetic field of the low-frequency section (from is due to the flow of current I) through it, is equal to zero, in this case is equal to zero and mutual inductanceV

the capacity of M is between sections and, accordingly, is equal to zero, the coupling coefficient between sections, which allows

t / tj

Rig. 2

r / rs w

ten

76877

Claims (1)

change the distance between the axes of the coils and thereby increase the accuracy. Formula invented and A device for measuring the voltage of an alternating magnetic field containing a partitioned induction coil, sections of which are made in the form of cylindrical coils with parallel magnetic axes, the geometric centers of which are located 1 in a plane perpendicular to their longitudinal axis, while the first section is made in the form of a single coil, and each of the subsequent ones - in the form of several series-according to the included coils, characterized in that, in order to increase the accuracy of measurements, each coil, except the coil very high-frequency section, comprises two successively and according included concentric windings with parallel axes, each coil after-blowing section 25 uniformly arranged along the cylindrical generatrix in the gap between two windings of each coil previous section., J T5 20 1-1 1-2 2-1 2-2 2-3 Ue. J 2-1 8ts FIG. four BB B1 R & B1 1-2