SU1071981A1 - Induction-type magnetometer - Google Patents

Description

The invention relates to magnetometry and can be used in geophysics in the study of natural and artificial magnetic fields with a wide frequency range in the dielectric and conductive media with electric power.

Known induction magnetometers for measuring variable magnetic fields, based on induction of emf in turns of the frame, placed in a variable magnetic field. Known magnetometers contain primary converters in the form of a single or multiple turn frame with a core of ferromagnetic material, an amplifier for increasing the signal level from the primary converter and unit registration GP.

The disadvantage of the devices is low sensitivity.

The closest in technical essence to the invention is a device for measuring an alternating magnetic field containing a frame primary transducer in the form of a circular pl square squared, preamplifier and recording unit. In the device, the course of the loop antenna is directly connected to the input of the amplifier G2}.

A disadvantage of the known device is the low sensitivity and accuracy of measurement.

The purpose of the invention is to increase the sensitivity and accuracy of measurements by eliminating the influence of interference from an electric field with a non-uniform scale larger than the sensor.

The goal is achieved by the fact that an inductive magnetometer consisting of a frame primary converter in the form of a round or square turn, a preamplifier and a registration unit has four matching transformers, and the primary converter turn is made in four equal sections, the midpoints of which are interconnected by radial conductors with a common point in the center of the coil, between the sections include the primary windings of matching transformers, while the secondary windings of two pairs are diametrically About opposite matching transformers are connected in series and according to included between the common point in the center of the coil, as well as the inverting and non-inverting inputs of the pre-amplifier, the output of which is connected to the registration unit.

The drawing shows the block diagram of the device.

The device contains a ray primary primary generator I in the form of a square coil divided into four equal sections 2. The middle of sections 2 are interconnected by radial conductors 3 with common point 4 in the center of the coil. Between sections 2, primary windings 5 of matching transformers are included b. The secondary windings of 7 two pairs of diametrically opposite matching transformers b are connected in series and are connected according to between {the point and the inverting and non-inverting inputs of the preliminary

5 amplifier 8. The output of the amplifier 8 is connected to the input of the registration unit 9.

The device works as follows.

When the primary converter 1 is placed in harmonically varying with frequency (JU, a uniform magnetic field with induction Bj, directed to the cool of the plane of the equipment, a partial EMF is induced in each section, formed by the coil section and shorting radial conductors 3

6 jUJ5 / 4-B2, where 5 is the coil area.

-1B force of symmetry currents in all

the coil sections are the same, and there are no currents in the shorting radial conductors 3.

If we neglect the inductances of dissipation and the resistances of the windings of the transformer 6, the voltage of the signal brought to the input of the amplifier 8 can be written as

where RD is the input impedance of the amplifier 8 at the differential input;

5 (. | - the impedance of the primary winding of the matching trans (5xRmator 6;

) - output impedance of the primary converter 1.

QIf in the measurement zone is valid

homogeneous electric field of strength E, then when decomposed into orthogonal components

-T xEx + evEv + zEz / where 6,, 6.62 are single units in the received coordinate system.

The voltage induced in the square turn of the pfvichnogo converter 1 with side b of the proposed magnetometer of each component

since e is perpendicular to dC;

# e, e ,,., f ,, - oi vd her

ivi

E ,, d

.

M CD

Thus, interference from a uniform electric field does not affect the readings of the magnetometer, whereas for a known alternating magnetic field meter with the same geometrical dimensions

(ii-v},

CD

m

since it is induced in the EMF circuit from the action of an electric field due to asymmetry caused by the inclusion of a load (or the presence of a gap) on one side of the coil. When measuring the magnetic field near the conductive bodies, a capacitive coupling of the frame primary 1Feater 1 occurs through an electric field with the conductive body, resulting in additional interference due to the potential difference between the amplifier body and the conductive body in the presence of capacitive coupling. The potential difference is created by the source of interference e with the impedance Zj, and the capacitive coupling is taken into account with the help of lumped capacitance C.

If for simplicity of calculations we assume a harmonic disturbance (our measurement, with an industrial frequency), the interference voltage at the input of the amplifier is defaulted by the expression (for a lime device);

 "NS

IVS „(W“ y)

where is Rn Oshivpenie prdvod acih

wires;

RX amplifier input impedance; Z |. capacitance on

interference frequency Fr. A simple calculation implies that dp of the proposed magnetometer (due to the cxei рии i) Un 0.

Thus, the magnetometer is not sensitive to the electric field and the influence of conductive masses, which makes it possible to significantly improve the measurement accuracy of the magnetic field and the sensitivity of the magnetometer.

Claims (1)

INDUCTION MAGNETOMETER, consisting of a frame primary transducer in the form of a round or square coil, pre-power and a recording unit, characterized in that, in order to increase the sensitivity and accuracy of measurements by eliminating the influence of interference from the electric field with a large size inhomogeneity scale, sensor, four matching transformers are introduced into it, and the coil of the primary Converter is made in the form of four equal sections, the middle of which are connected by a meode to a radial conductor with a common point in the center of the coil, between the sections the primary windings of the matching transformers are included, while the secondary windings of two pairs of diametrically opposite matching transformers are connected in series and according to and including between the common point in the center of the coil and the Inverting and non-inverting inputs of the pre-amplifier, the output of which is connected to the registration unit. SU „„ 1071981