SK284162B6 - The measuring insulation alternating current converter - Google Patents

Abstract

The measuring insulation alternating current converter comprising of an excitation winding and a pick-up winding attached to the electronic phase circuit input. The conductor (1) of the excitation winding is formed into a two-dimensional or a three-dimensional periodic system of parallel sections (3) of the excitation winding conductor (1) oriented in such a way that the conductor (1) of the excitation winding in adjacent parallel sections (3) is oriented opposite each other and at least one turn of the conductor (2) of the pick-up winding in a parallel position according to the conductor (1) of the excitation winding.

Description

Technical field

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to AC / AC isolation measuring transducers for an electrical voltage or current.

BACKGROUND OF THE INVENTION

The alternating current circuits for measurement purposes, which also provide the galvanic isolation function of the transmitter output circuit from the circuit being measured, are based on the transmission of electric current through a magnetic field, an electric field in capacitors, or an electromagnetic field in optical transmission elements. The known circuits work in principle either with direct conversion by means of a magnetic field generated by the measured current or by converting the measured current to an auxiliary quantity which is transferred via a magnetic, electric or electromagnetic field to the galvanically isolated part of the circuit. . Transmitters based on the Snake phenomenon are also known which directly convert the magnetic field created by the measured current to the output voltage, but the accuracy of the conversion is limited by the relatively low stability of the parameters of the Snake probes. Therefore, they are virtually not used in precision applications. The advantage of current transmission through the magnetic field in transformers is that the transmission is direct, and hence in principle allows maximum transmission accuracy. For this reason, only transformers are practically used for accurate conversion. The disadvantage of direct current transfer through the transformer is that the presence of a DC component in the measured current affects the magnetic properties of the transformer core and thus reduces the accuracy of the transfer. Methods of electronic compensation of the influence of the direct current component of the measured current on the transmission are known, their common disadvantage is the need for a complicated electronic and magnetic circuit, which brings a considerable increase in realization costs.

There is also known a method of transferring alternating current without a ferromagnetic core, in which the measuring transducer consists of an excitation winding, from which a voltage is induced into the sensing winding via mutual inductance and this output voltage is then phase corrected in an electronic phasing circuit. Due to the problematic suppression of the influence of external magnetic fields, this method is only used for high frequency applications.

SUMMARY OF THE INVENTION

AC measuring transducer consisting of an excitation winding and a sensing winding connected to the input of an electronic phasing circuit. The drive winding conductor is shaped into a planar or spatial periodic array of parallel sections of the conductor, which are oriented in such a way that the electric current in opposite parallel sections is opposite to one another. This conductor arrangement creates a periodic spatial magnetic field in the space filled by the excitation winding. Outside this space, the magnetic field quickly disappears. The sensing winding formed by the conductor guided in parallel with the excitation winding is oriented synchronously with the periodic magnetic field and therefore the partial contributions of the periodic field-induced voltage in the sensing winding are calculated. The external magnetic field has little effect on the resulting induced voltage, since its partial contributions are compensated for each other in opposite directions. Another advantage of the spatial arrangement of the excitation winding according to the invention is the rapid disappearance of the magnetic field of the excitation winding outside this winding, which is manifested also by the reduction of the influence of the surrounding properties on the mutual coupling of the excitation and sensing windings.

By shielding the electrically conductive material placed between the excitation and sensing winding conductors, it is possible to suppress the parasitic capacitive transmission of the voltage signal from the excitation to the sensing winding.

Placing the excitation winding and sensing winding together in the cavity of the electrically conductive material body reduces the coupling of both windings to the environment, thereby reducing the radiation, the effect of the environment on the coupling coefficient and the sensitivity of the transmitter to external magnetic fields.

The phase of the AC isolation converter may be advantageously realized such that the field winding is connected between the signal ground and the non-inverting input of the operational amplifier, the reference resistor is connected between the signal ground and the inverting input of the operational amplifier. an operational amplifier input, wherein a low pass filter is also connected between the output and the inverting operational amplifier input such that a low pass filter input is connected to the operational amplifier output and a low pass filter output is connected to the inverting operational amplifier input.

Due to the circumferential simplicity, it is advantageous to use an AC measuring transducer in electronic meters.

BRIEF DESCRIPTION OF THE DRAWINGS

In FIG. 1 shows an AC measuring transducer in principle.

In FIG. 2 shows in principle a shielded AC measuring transducer.

In FIG. 3 shows, in principle, an example of the connection of a phasing circuit of an AC measuring converter.

In FIG. 4 shows in principle another circuit of the AC isolation converter phasing circuit.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 shows, in principle, an AC measuring transducer whose excitation conductor 1 is shaped into a spatial periodic system of four parallel conductor sections (3) oriented in such a way that adjacent parallel sections are oppositely oriented with respect to current flow. Four windings of the sensor winding conductor 2 are guided parallel to the excitation winding conductor 1. The conductor of the sensing winding is provided with a shield 9 extending through the space between the sensing and excitation windings.

In FIG. 2 shows an AC measuring transducer whose excitation winding conductor 1 and the sensing winding conductor 2 are housed in a cavity of a body of electrically conductive material.

In FIG. 3 shows an alternating current phasing circuit in which the field winding 2 is connected between the signal ground and the non-inverting input of the operational amplifier 14. The reference resistor 13 is connected between the signal ground and the inverting input of the operational amplifier 14. The integrating capacitor 15 is connected between the output and an inverting input of the operational amplifier 14 and parallel to the integrating capacitor between the output and the inverting input of the operational amplifier 14 is connected to the inlet filter 16. The filter is connected such that a lowpass filter input is connected to the output of the operational amplifier. low pass filter output 16.

Industrial usability

The AC transducer can be used as an input circuit for gauges and measuring systems to measure AC, power, and electrical power.

Claims (4)

PATENT CLAIMS An alternating current measuring transducer comprising an excitation winding and a sensing winding connected to an input of an electronic phasing circuit, characterized in that the excitation winding conductor (1) is shaped into a flat or spatial periodic array of parallel excitation conductor sections (3). windings oriented so that adjacent parallel sections (3) are oppositely oriented in terms of electric current flow and at least one thread of the sensor winding conductor (2) is guided in parallel with the driving winding conductor (1). 2. The alternating current measuring transducer according to claim 1, characterized in that the space between the sensor winding conductor (2) and the field winding conductor (1) is provided with a shield (9) of electrically conductive material. An alternating current measuring transducer according to claims 1 and 2, characterized in that the excitation winding (1) and the sensing winding (2) are co-located in a cavity of the body (10) of an electrically conductive material. The AC current converter according to claims 1 to 3, characterized in that the phasing circuit comprises at least an operational amplifier (14), a reference resistor (13), an integrating capacitor (15) and a low-pass filter (16), the excitation winding ( 2) is connected between the signal ground and the non-inverting input of the operational amplifier (14), the reference resistor (13) being connected between the signal ground and the inverting input of the operational amplifier (14), the integration capacitor (15) connected between the output and the inverting input of the operational amplifier a low pass filter (16) is connected between the output and the inverting input of the operational amplifier (14), so that the low pass filter (16) and the inverting input of the operational amplifier (14) are connected to the output of the operational amplifier (14). ) the output of the low pass filter (16) is connected.