KR101190926B1 - Contactless current measuaring device - Google Patents

Abstract

PURPOSE: A contactless current measuring apparatus is provided to measure current without the cut and separation of an electric cable with a contactless method. CONSTITUTION: Housing comprises an electric wire groove for inserting an electric cable. A first sensor module is arranged along the outer circumference of the electric wire groove. The sensor module measures a discharged magnetic field of the electric cable and contact pressure with the electric cable. A memory(160) comprises a magnetic field table. The magnetic field table defines a current value for pressure and a magnetic field. A current measurement controller(150) calculates a magnetic field mean value for a magnetic field measured in the sensor module based on the magnetic field table. The current measurement controller displays the current value corresponding to the magnetic field mean value in a display unit. [Reference numerals] (140) Input unit; (151) Three-shaft average electric field calculating unit; (152) Current value calculating unit; (160) Memory; (161) Electric field table; (170) Display unit

Description

Contactless current measuring device {Contactless current measuaring device}

The present invention relates to a non-contact current measuring device, and more particularly to a non-contact current measuring device for measuring the current without cutting the wire cable or inserted into the closed circuit detection sensor.

The measurement of the commercial alternating current is usually performed by cutting a wire cable and connecting the cut wire cable to a current meter to form a current path, and inserting the wire cable into a closed circuit detection sensor and detecting magnetic fields generated from the wire cable. It is measured by inferring the current through the wire cable.

In the most classical way, cutting wire cables requires direct connection with a current meter, which places a number of constraints on practical use in homes, businesses and industrial sites. Normally, when cutting a wire cable, after the current is measured with the wire cable, the wire cable must be welded again and insulated. If this process is repeated for a large number of wire cables, the current meter is connected to the wire cable. Work requires a lot of time and manual work.

In contrast, the closed-loop detection sensor is formed by winding a coil around a magnetic field core having a donut shape around a wire cable, measuring a magnetic field formed around the wire cable at the center of the magnetic field core, and measuring the measured magnetic field as a current value. The current value that conducts the electric wire cable by reducing it is measured. However, the closed loop detection sensor can be measured only when the wire cable is disconnected, and cannot be applied to a conventional wire cable having two or more wires.

This is because when the magnetic field is measured for a single-phase two-wire wire cable having a pair of closed-circuit detection sensors, one of the wire cables and the other current propagation direction are different from each other, so that each other cancels the magnetic field and, accordingly, cancels the magnetic field. This is because the calculated magnetic field fails to calculate a current value proportional to the magnetic field. Therefore, the conventional closed-loop detection sensor applies a method of measuring a single wire after separating the single wire from the two-wire or three-wire wire cable one by one.

This type of measurement causes inconvenience for the current measuring device to separate all the wires into a single wire.

As a non-contact current measuring device, Korean Patent Laid-Open Publication No. 10-2001-0016949 has proposed a non-contact current and temperature detecting device for more accurately measuring a current value of a magnetic field value measured by a Hall sensor by compensating for temperature. . However, the non-contact current and temperature detector disclosed in Korean Patent Laid-Open Publication No. 10-2001- 0016949 is similar to the conventional closed-loop detection sensor in that the current is measured for a single wire, and the current value is measured using a magnetic field. In order to do this, it is still different from the conventional one in that the wire cable must be separated into a single wire.

An object of the present invention is to provide a non-contact current measuring device capable of measuring the current value in a non-contact manner without disconnecting the wire cable.

According to the present invention, the above object is a housing having a wire groove for inserting a wire cable, arranged along the outer circumferential surface of the wire groove and spaced apart from each other and the contact pressure with the wire cable and the magnetic field radiated from the wire cable A sensor module including a first sensor module, a second sensor module, and a third sensor module to measure, a memory having a magnetic field table in which current values for magnetic fields and pressures are defined, and the first sensor module with reference to the magnetic field table And a current measurement controller for obtaining a magnetic field average value of the magnetic field values measured by the third sensor modules, and displaying a current value corresponding to the magnetic field average value on the display unit.

According to the present invention, it is possible to measure the current value in a non-contact manner for a wire cable having a structure in which a plurality of wires are inserted into a single-phase two-wire, three-phase three-wire, and other single wire cable without separating a single wire separately.

1 is a block diagram of a non-contact current measuring device according to an embodiment of the present invention.
2 shows an external view of a current measuring device according to an embodiment of the present invention.
3 illustrates a reference diagram for frequency filtering characteristics of a bandpass filter and a lowpass filter.
4 shows a reference view of the structure of an electric wire groove.
5 shows a reference view for an example in which a magnetic field sensor is disposed.

The wire cable referred to in the present invention may refer to a form in which several individual wires are embedded in one tube or a shape in which one individual wire is inserted in one tube. If several individual wires are contained within a tube, each individual wire can be insulated from neighboring individual wires by rubber, plastics, plastics and various other non-conductors.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a block diagram of a non-contact current measuring device according to an embodiment of the present invention.

Referring to FIG. 1, a non-contact current measuring device (hereinafter, referred to as a “current measuring device”) according to an exemplary embodiment may include a sensor module 101, a current measuring controller 150, an input unit 140, and a memory 160. And a display unit 170.

Sensor module 101 may be composed of a first sensor module 110, a second sensor module 120 and a third sensor module 130, each sensor module (110, 120, 130) for the wire cable The magnetic field values of the wire cable can be detected at different positions. This is to refer to the fact that the magnetic field values emitted by individual wires vary depending on the position of the individual wires embedded in the wire cable. In the case of a single-phase two-wire wire cable having a ground wire, one of the first sensor module 110, the second sensor module 120, and the third sensor module 130 constituting the sensor module 101 is adjacent to the ground wire. In this case, the magnetic field value can hardly be output when adjacent to the ground line. That is, one of the first sensor module 110, the second sensor module 120, and the third sensor module 130 may have a measured magnetic field value close to “0”.

The first sensor module 110, the second sensor module 120, and the third sensor module 130 may include pressure sensors 116, 126, and 136, respectively. The pressure sensors 116, 126, 136 protrude toward the wire cable, and after protruding, convert the force exerted by the wire cable into a pressure value. The pressure sensors 116, 126, 136 are magnetic field sensors 111, 112. , 113) is used to determine how close the wire cable is to the cable.

The first sensor module 110 may include a magnetic field sensor 111, a shielding layer 112, a bandpass filter 113, a lowpass filter 114, and an amplifier 115.

The magnetic field sensor 111 is formed by winding a coil of 0.1 mm to 1 mm on the cylindrical ferrite core 111 a and wound from 2,000 turns to 6,000 turns. When the magnetic field sensor is positioned adjacent to the electric wire cable, the magnetic field sensor 111 is emitted from the electric wire cable. The magnetic field value can be obtained.

The bandpass filter 113 has a frequency pass band of 30 Hz to 120 Hz. The bandpass filter 113 is for detecting a conduction current of a wire cable having a frequency of 60 Hz band. The band pass filter 113 removes high frequency and harmonics exceeding 120 Hz, and filters the frequency band below 30 Hz. Minimize the impact on

In this embodiment, the frequency band for passing the 30Hz to 120Hz band is illustrated, but the passband of the bandpass filter 113 may be set lower than 30Hz or higher than 120Hz.

The low pass filter 114 performs low frequency filtering on the output value of the band pass filter 113 to provide only the magnetic field generated from the wire cable to the amplifier 115. The low pass filter 115 may set a slightly higher frequency of 70 Hz or less as a pass band when the commercial AC is 60 Hz. Through this, magnetic field values in the 70 Hz to 120 Hz band may be prevented from entering the amplifier 115.

The amplifier 115 may amplify the output value of the low pass filter 114 and provide it to the current measurement controller 150. Preferably, the amplifier 115 may be a two-stage or three-stage amplifier connected to Darlington, and a pre-amp is provided at the first stage, and the power amplifier may amplify the output of the pre-amplifier again. It may be implemented in the form. However, it is not limited.

The second sensor module 120 and the third sensor module 130 have the same structure and function as the first sensor module 110. For example, the magnetic field sensors 121 and 131, the shielding layers 121a and 131a, the bandpass filters 123 and 133, and the lowpass filters 124 and 134 of the second and third sensor modules 120 and 130. ), The amplifiers 125 and 135, and the pressure sensors 126 and 136, respectively, the magnetic field sensor 111, the shielding layer 111a, the bandpass filter 113, and the looppass filter 114 of the first sensor module 110. ), The amplifier 115 and the pressure sensor 116. Since the functions are the same, the descriptions of the components of the second sensor module 120 and the third sensor module 130 apply to those of the first sensor module 110 mutatis mutandis.

The current measuring controller 150 obtains the magnetic field value and the pressure value measured by each of the first sensor module 110, the second sensor module 120, and the third sensor module 130, and calculates an average magnetic field value based on the measured magnetic field value and the pressure value. The current magnetic field value is calculated by referring to the magnetic field table 161 provided in the memory 160. Here, the magnetic field table 161 means data defining current values according to average magnetic field values and pressure values.

The average magnetic field value may be an arithmetic mean value calculated for the magnetic field values measured by each of the first sensor module 110, the second sensor module 120, and the third sensor module 130. Alternatively, the average magnetic field value may be a value calculated by summing up the largest magnetic field value and the second largest magnetic field value and then dividing it. However, among the magnetic field values measured by the first sensor module 110 to the third sensor module 130, the measured value of the sensor module 110 to 130 adjacent to the ground line of the wire cable may be very small.

 Preferably, the current measurement controller 150 may be configured of a three-axis average magnetic field calculator 151 and a current value calculator 152.

The 3-axis average magnetic field calculator 151 calculates an average magnetic field value with respect to the magnetic field values measured by the first sensor module 110, the second sensor module 120, and the third sensor module 130, respectively, and is calculated. With reference to the magnetic field table 161, the pressure value calculated by each of the first sensor module 110 to the third sensor module 130 is readjusted to the average magnetic field value, and the size of the average magnetic field is readjusted. The corresponding current value can be calculated. In this case, the larger the pressure value, the smaller the average magnetic field value is calculated, and the smaller the pressure value, the larger the average magnetic field value is preferably calculated. The closer the wire cable and the magnetic field sensors 111, 121, and 131 are in close contact with each other, the larger the magnetic field value is measured. The farther the magnetic field sensors 111, 121, and 131 are away from each other, the magnetic field values are measured by the magnetic field sensors 111, 121, and 131. This is because the magnetic field value becomes smaller.

The input unit 140 may include a key for turning on and off the current measuring device according to the present embodiment, a direction key for selecting a menu, and a selection key. The input unit 140 may be provided with a menu key for calling a menu for selecting a standard wire standard and a selection key for selecting a standard wire selected by the menu key. In the case of standard wires, it is possible to know in advance the distance between individual wires and tubes provided in the wire cable and the overall diameter of the individual wires.The magnetic field table can define the current value of each standard wire, and the current measurement controller The reference numeral 150 may acquire current value information corresponding to the average magnetic field value and the pressure value for each standard wire defined in the magnetic field table.

The display unit 170 may display the current value measured by the current measurement controller 150. If the display unit 170 is coupled to the touch panel to drive the touch screen, the input unit 140 may be integrally formed with the display unit 170.

2 shows an external view of a current measuring device according to an embodiment of the present invention.

Referring to FIG. 2, the current measuring device includes a housing 180, a display unit 170 exposed on one side of the housing 180, and an input unit 140, and an upper end of the housing 180. An electric wire groove 190 for inserting the electric wire cable 5 may be provided.

The wire groove 190 has a shape recessed in a semicircle toward the inside of the housing 180, the pressure rods (116a, 126a, 136a) may be located on the inner surface of the wire groove 190. The magnetic field sensors 111, 121, and 131 may be located around the pressure rods 116a 126a and 136a, or may be located inside the pressure rods 116a 126a and 136a.

Similarly, the pressure sensors 116, 126, 136 may also be located inside the pressure rods 116a 126a, 136a, or inside the wire groove 190 adjacent to the pressure rods 116a 126a, 136a. In this case, the pressure sensors 116a 126a and 136a and the magnetic field sensors 111, 121 and 131 may be integrally formed in the pressure rods 116a 126a and 136a. However, it is not limited.

3 shows a reference diagram for the frequency filtering characteristics of the bandpass filter 113 and the lowpass filter 114.

Referring to FIG. 3, the bandpass filter 113 sets only the frequency of the 30 Hz to 120 Hz band as a pass frequency, thereby removing harmonics or high frequencies of 120 Hz or more. The magnetic field value passing through the bandpass filter 113 may again provide only the magnetic field value measured by the magnetic field sensor 111 through the pass band of the low pass filter 114 to the amplifier 115.

Similarly, the band pass filters 123 and 133 and the low pass filters 124 and 134 of the second sensor module 120 and the third sensor module 130 also have a band pass filter of the first sensor module 110 in FIG. 3. The same operation as the 113 and the low pass filter 114, and overlapping description will be omitted.

4 shows a reference view of the structure of the wire groove 190.

Referring to FIG. 4, the pressure rods 116a, 126a, and 136a may protrude in the direction of the wire cable 5 when the wire cable 5 is inserted into the wire groove 190. The pressure rods 116a, 126a, and 136a may protrude in the wire cable 5 direction by the input unit 140 or may be inserted into the housing 180. The magnetic field sensors 111, 121, 131 may be inserted into the pressure rods 116a, 126a, 136a, or the pressure sensors 116, 126, 136 may be inserted therein, and the magnetic field sensors 111, 121, 131 may be inserted therein. Adjacent to the pressure rods 116a, 126a, 136a, but spaced apart from the pressure rods 116a, 126a, 136a, they may be exposed to the wire grooves 190 or embedded inside the outer circumferential surface of the wire grooves 190. .

5 shows a reference view for an example in which a magnetic field sensor is disposed.

Referring to FIG. 5, the magnetic field sensors 111, 121, and 131 may be arranged along the outer circumferential surface of the wire cable 5 when the wire cable 5 is inserted into the wire groove 190. The magnetic field sensors 111, 121, and 131 may be spaced apart from each other by 120 degrees with respect to the wire cable 5. The magnetic field sensor 111 located on the outer circumferential surface of the electric wire cable 5 is adjacent to the individual electric wire 51, the magnetic field sensor 131 is adjacent to the individual electric wire 52, and the magnetic field sensor 53 is the individual electric wire 53. ) And an example of neighboring. At this time, the measured value of the magnetic field sensor 111 and the magnetic field sensor 131 is the maximum value, but the direction of the magnetic field is opposite, and the measured value of the magnetic field sensor 121 is adjacent to the ground line of the wire cable 5, so the measured value is minimal. Can be.

Since the measured values of the magnetic field sensor 111 and the magnetic field sensor 131 are in the reverse direction of the current flow of the commercial alternating currents of the individual wires 51 and 53, the reverse magnetic field may cancel each other when measured at a long distance. have. However, in this embodiment, each of the magnetic field sensors 111, 121, and 131 is in contact with the individual wires 51 to 53 in close contact with the individual wires 51 to 53 before the magnetic fields of the individual wires 51 to 53 cancel each other. The magnetic field value of) is measured and amplified and provided to the current measurement controller 150.

In the conventional closed-loop sensor having a donut shape having a diameter of 10 cm or more and having an empty center, the magnetic fields of the individual wires 51 and 53 are formed in opposite directions according to the advancing direction of the reverse AC current. The magnetic field sensors 111 and 131 of the present embodiment in close contact with 5) may not cause such a problem.

101: sensor module 110: first sensor module
111: magnetic field sensor 111a: ferrite core
112: shielding layer 113: bandpass filter
114: low pass filter 115: amplifier
140: input unit 150: current measurement control unit
151: 3-axis average magnetic field calculation unit 152: current value calculation unit
160: memory 161: magnetic field table
170: display unit

Claims (10)

A housing having a wire groove for inserting the wire cable;
A sensor module disposed spaced apart from each other along the outer circumferential surface of the wire groove and including a first sensor module, a second sensor module, and a third sensor module measuring contact pressure with the wire cable and a magnetic field radiated from the wire cable;
A memory having a magnetic field table in which current values for the magnetic field and pressure are defined; And
A current measurement controller which obtains a magnetic field average value of the magnetic field values measured by each of the first sensor module and the third sensor module by referring to the magnetic field table, and displays a current value corresponding to the magnetic field average value on a display unit; Non-contact current measuring device, characterized in that. The method of claim 1,
The magnetic field table,
Non-contact current measuring device characterized in that for defining the current value for each pressure with respect to the average magnetic field value measured by the sensor module. The method of claim 1,
Each of the first sensor module, the second sensor module, and the third sensor module,
Magnetic field sensors;
A bandpass filter that passes a band of 30 Hz to 120 Hz with respect to the detection value of the magnetic field sensor;
A low frequency filter that passes only a band of 70 Hz or less with respect to an output value of the band pass filter; And
Non-contact current measurement device comprising a; amplifier for amplifying the output of the low frequency filter. The method of claim 3,
The magnetic field sensor,
Non-contact current measuring device characterized in that the coil of 0.1mm to 1mm wound around 2000 to 6,000 turns in a 10mm to 15mm diameter ferrite core. The method of claim 1,
Current measurement control unit,
A three-axis average magnetic field calculator for calculating a magnetic field average value of the magnetic field values detected by the first to third sensor modules; And
And a current value calculator for calculating a current value for the average magnetic field calculated by the three-axis average magnetic field calculator with reference to the magnetic field table. The method of claim 1,
The wire groove is,
It is formed in a semi-circular toward the housing to allow the wire cable to be inserted and detached,
Non-contact current measuring device, characterized in that the first sensor module, the second sensor module and the third sensor module is provided on the inner surface of the wire groove is spaced at a predetermined separation angle. The method of claim 6,
The separation angle is,
Non-contact current measuring device, characterized in that 120 degrees. The method of claim 6,
The first sensor module to the third sensor module,
And three pressure rods each protruding toward the wire cable from the inside of the wire groove.
The pressure bar generates a pressure value according to the state of close contact with the wire cable and provides it to the current measuring control unit, characterized in that the non-contact current measuring device. 9. The method of claim 8,
The first sensor module to the third sensor module,
Non-contact current measuring device, characterized in that each formed integrally with one of the pressure rods. The method of claim 1,
The first sensor module to the third sensor module,
Non-contact current measuring device, characterized in that each is shielded by a metal shielding layer.

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