SU1185423A1 - Versions of current transducer - Google Patents

Description

The invention relates to automation and can be used in devices for automatic regulation and control.

The aim of the invention is to expand the operational capabilities of the sensor.

FIG. I shows a reed switch surrounded by a screen of an electrically conductive diamagnetic material in a magnetic field of a conductor; in fig. 2 - reed switch, the case of which is made of an electrically conductive diamagnetic material, and the contacts are isolated from the case in a magnetic field of a conductor; in fig. 3 presents: οί —the dependence of the amount of direct current in the controlled circuit, necessary for the sensor to operate, on the thickness of the screen (reed switch housing) made of a conducting diamagnetic material; β — Dependence of the actual value of the alternating current necessary for the sensor to operate on the thickness of the screen (reed switch housing) made of a conducting diamagnetic material; in fig. 4 shows the dependence of the effective value of the alternating current necessary for the sensor to operate on the frequency of the alternating current for different values of the screen thickness (the reed switch bulb).

The sensor (Fig. I) contains a reed switch I, a screen 2 made of an electrically conductive diamagnetic material, the conductor 3, the indicator 4 of the reed switch actuation.

The sensor of FIG. 2 contains a reed switch 1, the body of which, acting as a screen 2, is made of an electrically conductive diamagnetic material, bushings 5 made of any non-ferromagnetic dielectric material, the conductor 3, the indicator 4 of the reed switch.

The choice of the type of electrically conductive diamagnetic material depends on the specific conditions of use.

An indicator of the reed switch is, for example, ohmmeter.

The sensor works as follows.

When an alternating current flows through a conductor 3 around the latter, an alternating magnetic field arises, which, according to the law of electromagnetic induction, induces eddy currents in the screen body 2 (Fig. 1) or in the reed switch 1 (Fig. 2). In turn, the eddy currents in the screen housing 2 (Fig. 1) or the reed switch 1 (Fig. 2), according to the same law, excite an alternating magnetic field, always directed oppositely to the original magnetic field.

The intensity of the resulting alternating magnetic field is always less than the intensity of the initial alternating magnetic field by the magnitude of the magnetic field generated by the vortex

currents in the case of the screen 2 (Fig. 1) or

reed switch 1 (Fig. 2).

The reed switch I triggers under the influence of the amplitude of the resulting alternating magnetic field induced by the alternating current in the conductor 3, and the indicator 4 detects the fact of tripping.

When exposed to a magnetic field induced by direct currents in the conductor 3, the reed switch 1 also works.

When the current reaches the value of L (Fig. 3, the point A of the intersection of dependencies

and β) (you can determine the thickness of the screen 2 (Fig. 1) or the thickness of the body of the reed switch 1 (Fig. 2).

When the current reaches the value of L! (Fig. 3 point A screen 2 (Fig. 1) or the body of the reed switch 1 (Fig. 2) attenuates the amplitude of the alternating magnetic field 12 times, which corresponds to the actual value of the magnetic field induced by alternating current in the conductor 3.

In a DC magnetic field, the magnitude of which is equivalent to the actual value of the alternating current, the reed switch 1 also works when the current L reaches the value L] [at point A (Fig. 3).

Thus, the sensor operates on the amplitude value of the alternating current, equivalent to the actual value of the alternating current in the conductor 3.

Adjustment of the sensor response in an alternating current magnetic field, equivalent in magnitude to the actual value of the alternating current, is carried out by moving the reed switch 1 relative to the conductor 3.

The depth of penetration of an alternating magnetic field into an electrically conductive diamagnetic material is inversely proportional to the frequency of the alternating magnetic field. For a given screen thickness (the reed switch housing) (Fig. 4) L _g , L _g , L ₅ and the frequency change of the magnetic field induced by alternating current, the depth of penetration of the alternating magnetic field changes and the sensor responds when the magnetic field reaches a value corresponding to the sensitivity of the reed switch i.e. it works as an ac frequency sensor. FIG. 4 shows that for given values of the screen thickness (the reed switch housing) L ₂ , L _e at a certain value of the frequency of the alternating current, different effective values of the alternating current in the conductor 3 are needed for the sensor to operate: ^ 1, Лг. F>

In the initial state at a given position of the sensor in a magnetic field of alternating current of a given frequency reed switch 1 is not

closed As the frequency of the alternating current decreases, the depth of the pro3 increases.

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The presence of an alternating magnetic field in the screen material 2 (Fig. 1) or the body of the reed switch 1 (Fig. 2) reduces the degree of absorption of the magnetic field by the diamagnetic conductive material and upon reaching the controlled frequency the reed switch is triggered.

Claims (2)

1. The current sensor containing the conductors and the reed switch, characterized in that, in order to expand its operational capabilities, it is equipped with a screen that is made of an electrically conductive diamagnetic material and installed so that it covers the reed switch. 2. Current sensor containing conductors and reed switches, characterized in that, in order to expand its operational capabilities, the reed switch body is made of an electrically conductive diamagnetic material. Phage. ί 2 one II85423