RU111307U1 - DEVICE FOR MEASURING ELECTRIC FIELD TENSION - Google Patents

Abstract

 A device for measuring electric field strength containing a spherical sensor with sensitive conductive electrodes located on the coordinate axis passing through the center of the sensor housing and symmetrically relative to its body, a differential sensor signal transducer, an alternating voltage to DC converter and a measuring device, while sensitive conductive electrodes connected to the first and second inputs of the differential Converter, the output of which is through a constant voltage generator is connected to the input of the measuring device, calibrated in units of electric field strength, and the sensitive conductive elements of the electrode are made in the form of a spherical layer, the external size of which is limited by a central cone with an apex angle of θ1≤90 °, and the inner one by a central cone with angle θ2 <θ1 at the vertex, selected on the basis of the required error and spatial range of measurement, characterized in that the sensor performs with one pair of senses electrically conductive electrodes, each sensitive conductive electrode of the sensor consists of two galvanically coupled electrically conductive sensitive elements, and the coordinate axis of the sensor exiting from its center passes between the axes of the two conductive sensitive elements forming the sensitive electrode at equal angular distances from these axes and lies in their plane.

Description

The utility model relates to the field of measurement technology and can be used to measure the electric field in a wide spatial range with increased accuracy.

A device for measuring electric field strength [Feser K. A potential free spherical sensor for the measurement of transient electric fields / K. Feser, W. Pfaff // IEEE Transaction on Power Apparatus and Systems, vol. Pas-103. - 1984. - No. 10. - P. 2904-2911], containing a spherical sensor with three pairs of electrically conductive sensitive elements placed on its surface, pairwise located on the coordinate axes, passing through the center of the sensor housing, the sensitive elements being connected to the inputs of differential amplifiers, the outputs of which are connected to the inputs of the squares and the outputs of the quadrators through the adder are connected to the input of the root extractor, the output of which is connected to the output terminal of the device.

However, this device can be used to measure the electric field in a narrow spatial range, i.e. at distances from field sources significantly exceeding the size of the sensor. In this region, the electric field can be considered homogeneous. As the sensor approaches the source of the field, the electric field becomes inhomogeneous, and the measured voltage depends on the orientation of the sensor, which also leads to significant measurement errors. In addition, such a device has an extended range of conversion of input signals and has increased implementation complexity.

The closest device to the claimed is a device for measuring the electric field [Certificate for a utility model No. 26136 RF MKI G01R 29/08. Device for measuring electric field strength / S.V. Biryukov - Publ. 10.11.2002, Bull No. 31] containing a spherical sensor with three pairs of sensitive conductive elements, pairwise located on the coordinate axes passing through the center of the sensor housing and symmetrically relative to its body, a differential transducer of the sensor signals, an alternating voltage to DC converter and a measuring device, this, the first sensitive conductive elements of each pair are connected together at the first nodal point, and the second at the second nodal point, in turn the first nodal point connected to the first input, and the second to the second input of the differential transducer, the output of which is connected to the input of a measuring device calibrated in units of electric field intensity through an AC / DC converter, moreover, the sensitive electrically conductive elements are made in the form of a spherical layer, the external size of which is limited by the central cone with an apex angle θ ₁ ≤90 °, and the inside - with a central cone angle of θ ₂ <θ ₁ at the vertex selected within an error on the basis of the required minute and spatial span.

The advantage of this device is the simplicity of the circuit implementation, and the disadvantage is the significant errors in measuring the voltage at distances from the source of the electric field greater than or equal to 1.5 · R, where R is the conditional radius of the sensor housing and the complicated design of the sensor.

The objective of the utility model is to expand the spatial range of measurement of electric field strength towards smaller distances of 1.5 · R from the field source and to simplify the design of the sensor.

This problem is achieved by the fact that in the known device for measuring electric field strength, containing a spherical sensor with sensitive conductive electrodes, pairwise located on the coordinate axes passing through the center of the sensor housing and symmetrically relative to its body, a differential sensor signal transducer, an alternating voltage to DC converter and a measuring device, while the first sensitive conductive electrodes are respectively connected to the first m and with the second inputs of the differential transducer, the output of which is connected to the input of a measuring device calibrated in units of electric field intensity through an AC / DC converter, moreover, the sensitive electroconductive elements of the electrode are made in the form of a spherical layer whose external size is limited by a central cone with an angle at the apex θ ₁ ≤90 °, and the inside - with a central cone angle of θ ₂ <θ ₁ at the vertex selected based on the desired spatial errors and According to the claimed utility model, the sensor is made with one pair of sensitive conductive electrodes, each sensitive conductive electrode of the sensor consists of two galvanically coupled conductive sensitive elements, and the coordinate axis of the sensor exiting from its center passes between the axes of two conductive sensitive elements forming a sensitive electrode at equal angular α distances from these axes and lies in their plane.

The proposed utility model is illustrated by drawings of figure 1 - figure 5, where

figure 1 shows the sensor and the structural diagram of a device for measuring electric field strength;

figure 2 is an example of one of the possible forms of the sensitive elements 4-7 of the electrodes of the sensor 2-3, made, in the General case, in the form of a spherical layer with external θ ₁ and internal θ ₂ angular dimensions;

figure 3 - figure 5 - presents graphs of the error of the sensor depending on the spatial range of measurement and the angular dimensions of its sensitive elements with angular distances between the axes of the sensitive elements and the coordinate axis of the sensor α = 45 °.

A device for measuring the electric field strength contains a sensor 1 with a pair of conductive sensitive electrodes 2 and 3 located on its surface, centers 12 and 13 of which are placed on the axis of the Cartesian coordinate system symmetrically with respect to its beginning 14, a differential transducer 15, an alternating voltage to direct current converter 16 and a measuring one device 17. Sensitive electrodes 2, 3, respectively, consist of the same electrically conductive sensitive elements 4, 6 and 5, 1 in the form of spherical segments, Neighboring central external cone with an apex angle θ ₁ <90 °, in which the window cut central inner cone with an angle of θ ₂ <θ _1. Sensitive elements 4, 5 and 6, 7 are arranged in pairs symmetrically on diametrically opposite sections of the spherical conductive housing 1, isolated from it and one from the other. The axis of the pairs of sensing elements 4, 5 and 6, 7 pass through the center of the sensor 14 and the centers 8, 9 and 10, 11 of the pairs of sensing elements. The coordinate axis of the sensor leaves its center 14, passes through the centers 12 and 13 of the sensitive electrodes 2, 3, located between the axes of the pairs of sensitive elements 4, 5 and 6, 7 at an equal angle and the distance from them lies in the same plane with the axes of the sensitive elements 4, 5 and 6, 7. Sensitive elements 4 and 6 are galvanically connected and connected to the first input of the differential transducer 15, and sensitive elements 5 and 7 are galvanically connected and connected to the second input of the same differential transducer 15, the output of which is converter AC to DC 16 is connected to the input of the measuring device 17 is calibrated in terms of electric field intensity.

The device operates as follows.

A sensor 1 with sensitive electrodes 2 and 3 is placed in the space of the investigated alternating electric field, while on the sensitive electrodes 2 and 3 there are time-varying electric charges proportional to the component of the modulus of the vector of the measured field intensity, i.e. the sum of the source field and the sensor’s own field. A change in charges over time leads to the appearance of electric currents proportional to these charges. These currents contain a component due to the intrinsic field of the sensor 1. Due to the differential conversion of the signals from the sensitive electrodes 2 and 3 of the sensor 1, an alternating voltage U _~ is allocated to the output of the differential transducer 15, which is proportional to the magnitude of the voltage vector of the initial electric field E. This is the voltage 16 AC to DC is converted into a DC voltage U _=, which is measured by the measuring device 17, a calibrated in units ah electric field intensity.

To obtain the measurement result, the sensor 1 is oriented in an electric field until the maximum reading of the measuring device 17 is reached, which will correspond to the strength of the initial electric field. The maximum reading of the measuring device 17 will be achieved when the coordinate axis x of the sensor coincides with the direction of the electric field vector .

In this case, the readings N of the measuring device will be equal

where k is the dimensionless constant coefficient; k ₁ - coefficient taking into account the conversion factors of the current integrator, AC to DC converter and measuring device; ε ₁ is the dielectric constant of the medium in which the sensor is located; R is the radius of the sensor housing; φ, θ ₁ and θ _{2 are the} angular dimensions of the sensitive element made in the form of a spherical layer (φ = π) or its part (φ <π); σ (θ ₁ , θ ₂ , α) is the error of the sensor in an inhomogeneous EP, depending on the angles θ ₁ θ ₂ and parameter α; α = R | d is a parameter that determines the spatial range of measurement (d is the distance from the center of the sensor to the field source); E is the intensity of the initial electric field.

Reducing the error of the device and expanding the spatial range of measurement is achieved:

1) due to the organization of the sensitive electrode of the sensor from two galvanically coupled sensitive elements made in the form of spherical segments (spherical layers), the centers of which are deviated from the coordinate axis of the sensor in the general case by an angle α;

2) due to the optimal choice of the angular dimensions θ ₁ and θ _{2 of the} spherical layers.

Simplification of the design of the sensor is achieved through the use of one pair of sensitive electrodes instead of three in the prototype.

In this case, the distribution of charges induced on the surface of the sensor electrodes obtained in this way approaches the distribution in a uniform field.

From the graphs of FIGS. 3 to 5, it can be seen that a change in the external angular size θ _{1 of the} spherical segment and the internal angular size θ _{2 of the} window of the spherical layer with a fixed external angular size θ ₁ leads to both a decrease in the error of the sensor and the expansion of its spatial range measurements compared to the prototype.

Thus, when measuring the electric field, the sensor 1 is oriented in the field until the maximum reading of the measuring device 17 is obtained. Hold the sensor 1 in this position and the measuring device 17 measures the magnitude of the vector of the initial electric field.

The size of the sensitive elements made in the form of a spherical segment or a spherical layer is selected based on the maximum possible spatial range of measurement and the minimum possible measurement error, according to the graphs presented in figures 3-5 and tables 1-3.

According to figure 3 and figure 4, the optimal dimensions of the sensitive elements 4-7, made in the form of a spherical segment or part thereof lie in two ranges of changes in their angular dimensions: 47 ° <θ1 <60 ° at θ ₂ = 0 and 72 ° < θ ₁ <90 ° at θ ₂ = 0. The optimal dimensions of the sensitive elements 4-7, made in the form of a spherical layer (figure 5) with θ ₁ = 45 ° lie in the range of 8 ° <θ ₂ <22 °.

Table 1 - Dependences of the external angular size θ _{1 of the} sensitive element made in the form of a spherical segment with its internal size θ ₂ = 0 ° and the maximum possible parameter α _max. determining the spatial range of measurement from the required sensor error ± σ (for the first range) at angular distances between the axes of the sensing elements and the coordinate axis of the sensor α = 45 °.

σ,% 0.125 0.25 0.5 one 1.5 2 θ ₁ 60 58 56.5 53.4 51.5 50.1 α max 0.4 0.45 0.53 0.62 0.69 0.73 Continuation of table 1 σ,% 2.5 3 3.5 four θ ₁ ° 49.1 48.3 47.65 47.1 α _max 0.78 0.81 0.84 0.88

Table 2 - Dependences of the external angular size θ _{1 of the} sensitive element made in the form of a spherical segment with its internal size θ ₂ = 0 and the maximum possible parameter α _max , which determines the spatial measurement range, on the required sensor error ± σ (for the second range) for angular the distances between the axes of the sensing elements and the coordinate axis of the sensor α = 45 °.

σ,% 2.1 2.25 2.5 3 3.25 3.5 θ ₁ ° 90 83 80 77 76.2 75.4 α _max 0.88 0.93 0.99 0.99 0.99 0.99 Continuation of Table 2 σ,% 3.75 four 4.25 4.5 4.75 5 θ ₁ ° 74.8 74.2 73.7 73.3 72.9 72.55 α _max 0.99 0.99 0.99 0.99 0.99 0.99

From the analysis of tables 1 and 2 it follows that the best angular dimensions of the sensitive element made in the form of a spherical segment are angular dimensions θ ₁ = 90 ° and θ ₂ = 0, corresponding to errors σ = 2.1%. A spherical segment with such an angular size will be a hemisphere. Thus, the sensitive elements 4-7 are performed in the form of hemispheres formed by four congruent (equal) spherical triangles obtained by dissecting a sphere by three mutually perpendicular planes passing through the center of the sphere. Sensitive elements with angular sizes 47 ° <θ ₁ <90 ° and θ ₂ = 0 should be performed as part of a spherical segment.

Table 3 - Dependences of the internal angular size θ _{2 of the} sensing element made in the form of a spherical layer with its external size θ ₁ = 45 ° and the maximum possible parameter α _max , which determines the spatial measurement range, on the required sensor error ± σ at angular distances between the axes sensitive elements and the coordinate axis of the sensor α = 45 °.

σ,% 0.5 one 1.5 2 2.5 3 3.5 four 4.5 5 θ ₂ ° 22 18.5 16.1 14.5 13.1 12 11.1 10.3 9.5 8.8 α _max 0.46 0.6 0.74 0.86 0.97 0.99 0.99 0.99 0.99 0.99

From the analysis of table 3 it follows that the optimal angular dimensions of the sensing element, made in the form of a spherical layer is the angular dimensions θ ₁ = 45 ° and θ ₂ = 12 °, corresponding errors σ = 3%

In the tables, the parameter α _max = R | d _min , where R is the radius of the spherical body of the sensor; d _min - the minimum possible distance from the center of the sensor to the source of the field with the required error.

Thus, the spatial measurement range of the sensor will be in the range from d _min = R | α _max to ∞. Therefore, the greater the α _max ., The wider the spatial range and the closer to the source of the field the sensor can be located.

The claimed technical solution allows, with the right choice of configuration and size of the sensitive elements, to achieve a measurement error of less than ± 3% at distances from the field source and conductive surfaces greater than or equal to 1.01R, where R is the radius of the spherical housing of the sensor, and also to simplify the design of the sensor by using one, instead of three pairs of sensing elements.

Claims (1)

A device for measuring electric field strength containing a spherical sensor with sensitive conductive electrodes located on the coordinate axis passing through the center of the sensor housing and symmetrically relative to its body, a differential sensor signal transducer, an alternating voltage to DC converter and a measuring device, while sensitive conductive electrodes connected to the first and second inputs of the differential Converter, the output of which is through the ac voltage generator is connected to the input of the measuring device, calibrated in units of electric field strength, and the sensitive conductive elements of the electrode are made in the form of a spherical layer, the external size of which is limited by a central cone with an apex angle θ ₁ ≤90 °, and the inner one - by a central cone with an angle θ ₂ <θ ₁ at the vertex, selected on the basis of the required error and spatial range of measurement, characterized in that the sensor is performed with one pair of senses conductive electrodes, each sensitive conductive electrode of the sensor consists of two galvanically coupled electrically conductive sensitive elements, and the coordinate axis of the sensor emerging from its center passes between the axes of the two conductive sensitive elements forming the sensitive electrode at equal angular distances from these axes and lies in their plane.