SU752505A2 - Magnetic shield - Google Patents

Description

one

The invention relates to electrical engineering.

According to the main author. St. No. 649045 is known for a magnetic screen made in the form of a hollow body containing demagnetizing windings, the coils of which are orthogonal, sensors of spatial magnetic flux components located on mutually perpendicular planes of the magnetic screen body, and signal amplifiers of sensors connected to the outputs of demagnetizing windings 1 .

The disadvantage of this magnetic screen is the low reliability of its operation due to pickups in high-resistance input circuits and intermediate stages of amplifiers under the influence of external time-varying magnetic interference fields leading to a distortion of a given characteristic of the input-output amplifiers. As a result, in the device for some time there may be undercompensation or overcompensation of the external magnetic flux and penetration of the interference field into the screened region. The use of conventional shielding means to protect amplifiers from interference due to powerful magnetic fields (ferromagnetic shields) would significantly increase the overall dimensions of the device.

The purpose of the invention is to increase the effectiveness of shielding.

This goal is achieved by the fact that in a magnetic screen made in the form of a hollow body containing demagnetizing windings whose orbital surfaces are orthogonal, sensors of the spatial components of the magnetic flux located on mutually perpendicular planes of the magnetic screen body are connected to the outputs of the demagnetizing windings, the amplifiers of the sensor signals are placed inside the hollow body of the magnetic screen.

FIG. Figure 1 shows the layout of sensors and amplifiers relative to the body of the magnetic screen; in fig. 2 shows the wiring of sensors, amplifiers and windings.

Claims (1)

The magnetic screen consists of a hollow body 1, made in the form of a parallelepiped, the inner space of which is the area protected from the magnetic field. Sensors 2 and 3 of the magnetic flux (for example, Hall sensors) are superimposed on the mutually perpendicular surfaces of housing 1, i.e., those surfaces of the housing are used that are perpendicular to the spatial components of the magnetic flux to be suppressed. FIG. 1 and 2, the downstream and downward components of the flow (the plane with sensor 2) and from left to right or from right to left (the plane with sensor 3) are subject to suppression. Sensors 2 and 3 are connected to amplifiers 4 and 5, which by their outputs are connected to demagnetizing windings 6 and 7. Moreover, demagnetizing winding 6 is wound on housing 1 in such a way that its axis coincides with the direction of the spatial component of the magnetic flux acting perpendicularly of the surface of the corpus 1, on which the sensor 2 is superimposed, through an amplifier connected to this winding 6. B. Turn, the demagnetizing winding 7 is wound on the housing 1 in such a way that its axis coincides with the direction of the magnetic flux component ka, acting perpendicular to that surface of housing 1, on which sensor 3 is superimposed, through amplifier 5 connected to this winding 7. Amplifiers are shielded by the same magnetic screen, the operability of which they provide, since the internal space of the hollow housing 1 of the device according to the basic invention is protected from interference fields area. The magnetic screen works as follows. When a disturbance occurs, the magnetic flux of which acts, for example, in the direction perpendicular to the plane with sensor 2 (top to bottom), the output of the latter appears proportional to this flux signal, which is amplified by amplifier 4 and enters winding 6, creating It has an electric current, which, in turn, creates a magnetic flux directed against the flow of interference, i.e. from bottom to top, and almost equal to it. With an increase in the noise field, the counter-compensating field increases accordingly. Thus, penetration of the external field into the cavity of the housing 1 is prevented, i.e. the object located in it, as well as the amplifiers 4, 5, are protected from the magnetic field of the corresponding direction. If a field of interference occurs, the magnetic note of which acts in the direction perpendicular to the plane with sensor 3, sensor 3 - amplifier 5 - winding 7 likewise creates a magnetic flux that compensates for the interference field. In general, various spatial components of the interfering field are compensated. The invention makes it possible to abandon the protection of amplifiers in strong magnetic fields with special powerful shields and to increase the shielding efficiency without increasing the size of the device. A magnetic screen is most effective when used in conditions of strong time-varying magnetic fields, and especially to protect against magnetic fields created by the limiting short-circuit currents in high-voltage high-power systems such as autonomous, electric power systems. The invention of the Magnetic screen on the author. St. No. 649045, characterized in that, in order to increase the efficiency of shielding, sensor signal amplifiers are housed inside a hollow body of a magnetic screen. Sources of information taken into account during the examination 1. USSR author's certificate No. 649045, cl. G 12 V 17/02, 1977.