JP2017191018A - Current measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve measurement accuracy.SOLUTION: A current measurement device comprises: a main body part 2; a clamp sensor 3 having a pair of clamp arms and provided at the main body part 2 such that end portions of the respective clamp arms can be joined to and separated from each other through open/close operation, for detecting a detected amount generated by current flowing in a measurement object in the state in which the end portions are joined to each other to be a ring form surrounding the measurement object; a flexible sensor 4 provided separately from the main body part 2 and formed into a cable shape having flexibility, for detecting a detected amount in the state in which both end portions are joined to each other to be a ring form surrounding the measurement object; and a measurement section provided at the main body part 2, for measuring current on the basis of the detected amount. The flexible sensor 4 includes a flexible core formed from magnetic material.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a current measuring device that measures a current flowing through a measurement object.

  As this type of current measuring device, a current measuring device (clamp type multimeter) disclosed in Patent Document 1 below is known. The current measuring device is housed in a housing, a pair of clamp portions provided in the housing, a lever provided in the housing for opening and closing each clamp portion, a display provided in the housing, and a housing. A signal switching circuit and electronic circuits such as a processing circuit and an integrating circuit are provided. The current measuring device includes a Rogowski coil configured separately from the housing and configured to be connectable to the housing via a cable. Using either the clamp unit or the Rogowski coil It is possible to measure the current flowing through the measurement object.

  When measuring the current flowing to the measurement target using the clamp unit, the lever is operated to clamp the measurement target with the clamp unit, and then the signal switching circuit is operated to send the signal from the clamp unit to the processing circuit. input. Subsequently, the processing circuit measures the current flowing through the measurement object based on the input signal, and displays the current value on the display. On the other hand, when measuring the current flowing through the measurement object using the Rogowski coil, the measurement object is surrounded by the Rogowski coil, and then the signal switching circuit is operated to integrate the integration circuit output from the Rogowski coil. Signal) is input to the processing circuit. Subsequently, the processing circuit measures the current flowing through the measurement target based on the input signal, and displays the current value on the display. In this case, since the clamp part is provided in the housing in which the display is disposed, the current value displayed on the display can be visually recognized while confirming the state in which the measurement target is clamped by the clamp part. On the other hand, since the Rogowski coil has flexibility, it can be used by being deformed according to the shape of the measurement object, the presence of an obstacle around the measurement object, and the like. Further, since the Rogowski coil is connected to the housing via a cable, the current value displayed on the display can be visually recognized at a position away from the measurement target. Thus, in this current measuring device, it is possible to use the clamp part and the Rogowski coil properly according to the measurement mode.

U.S. Pat. No. 8,304,449

  However, the conventional current measuring apparatus has the following problems to be improved. That is, in this current measuring device, it is possible to selectively use the clamp part and the Rogowski coil depending on the measurement mode. However, the Rogowski coil is formed of a hollow coil, and due to its structure, it is difficult to improve detection accuracy. For this reason, this current measuring device has a problem that it is difficult to improve measurement accuracy when measuring current using a Rogowski coil, and improvement of this is desired.

  The present invention has been made in view of the problems to be improved, and a main object of the present invention is to provide a current measuring device capable of improving measurement accuracy.

  In order to achieve the above object, the current measuring device according to claim 1 is composed of a main body portion and a pair of clamp arms, and each end portion of each clamp arm is arranged on the main body portion so as to be able to contact and separate by opening and closing operations. The first sensor for detecting the detected amount generated by the current flowing through the measurement target in a state where the end portions are joined to form an annular body surrounding the measurement target, and the main body is configured separately. A second sensor for detecting the detected amount in a state of being formed into a flexible cable and having both ends joined together to form an annular body surrounding the measurement object, and disposed in the main body And a measuring unit that measures the current based on the detected amount, wherein the second sensor includes a flexible core formed of a magnetic material. ing.

  The current measuring device according to claim 2 is the current measuring device according to claim 1, wherein the second sensor includes a coil formed of a covered electric wire wound around the core. Yes.

  The current measurement device according to claim 3 is the current measurement device according to claim 1, wherein the second sensor includes a magnetic detection element disposed in the core or in the vicinity of the core. It is configured.

  The current measuring device according to claim 1, comprising: a first sensor disposed in the main body portion; and a second sensor formed separately from the main body portion and formed in a flexible cable shape, The second sensor includes a flexible core made of a magnetic material. For this reason, according to this current measuring device, the first sensor and the second sensor can be properly used according to the measurement mode, and the current sensor is deformed according to the shape of the measurement object, the presence of an obstacle around the measurement object, and the like. Therefore, it is possible to sufficiently improve the measurement accuracy when measuring the amount to be measured using the flexible second sensor that can be used.

  According to the current measuring device of the second aspect, the second sensor is configured by including the coil formed of the covered electric wire wound around the core, whereby the alternating current flowing through the measurement target is converted to the second sensor. It is possible to sufficiently improve the measurement accuracy when using and measuring.

  According to the current measuring device according to claim 3, since the second sensor is configured by including the magnetic detection element, the measurement accuracy when measuring the direct current flowing through the measurement object using the second sensor is sufficiently improved. Can be made.

1 is a configuration diagram showing a configuration of a current measuring device 1. FIG. 1 is a perspective view of a current measuring device 1. FIG. It is explanatory drawing explaining the structure of the main-body part 2 and the clamp sensor 3. FIG. It is explanatory drawing explaining the measuring method using the clamp sensor 3. FIG. 3 is an explanatory diagram illustrating a configuration of a flexible sensor 4. FIG. It is explanatory drawing explaining the measuring method using the flexible sensor 4. FIG. 4 is an explanatory diagram illustrating a configuration of a flexible sensor 104. FIG.

  Hereinafter, embodiments of a current measuring device will be described with reference to the accompanying drawings.

  First, the configuration of the current measuring device 1 as an example of the current measuring device will be described with reference to the drawings. The measuring apparatus 1 shown in FIGS. 1 and 2 is configured to be able to measure a current (a direct current and an alternating current) flowing through a measurement target (for example, the electric wire 100 shown in FIG. 3). Specifically, as shown in FIGS. 1 and 2, the current measuring device 1 includes a main body 2, a clamp sensor 3, and a flexible sensor 4.

  As shown in FIG. 1, the main body 2 includes a display unit 21, an operation unit 22, a processing unit 23, and a main body case 20 (see FIG. 2) in which each of these components is accommodated or arranged. ing.

  The display unit 21 is composed of a liquid crystal panel, for example, and is disposed on the front panel of the main body case 20 as shown in FIG. Further, the display unit 21 displays a current value or the like of a current (measured amount) according to the control of the processing unit 23. The operation unit 22 includes various switches 22a and a dial 22b arranged on the front panel of the main body case 20, and outputs operation signals according to these operations.

  The processing unit 23 controls each unit constituting the main body unit 2 according to the operation signal output from the operation unit 22. The processing unit 23 functions as a measurement unit and flows to the measurement target based on the detection signal Sd (detected amount detected by the clamp sensor 3 and the flexible sensor 4) output from the clamp sensor 3 and the flexible sensor 4. The current value of the current is measured, and the measured current value is displayed on the display unit 21.

  As shown in FIG. 3, the body case 20 of the body 2 is provided with a pair of operation buttons 20a for opening / closing (turning) the clamp arm 31 constituting the clamp sensor 3. . The main body case 20 is provided with a connector 20b for connecting a connector 43a attached to the signal cable 43 of the flexible sensor 4.

  The clamp sensor 3 corresponds to a first sensor and includes a pair of clamp arms 31 formed in an arc shape in plan view and a hall element 32 as an example of a magnetic detection element, as shown in FIG. Yes.

  As shown in FIG. 3, each clamp arm 31 includes, for example, a core 31a formed of a soft magnetic material (ferrite) and a clamp case 31b in which each core 31a is accommodated. Each clamp arm 31 is attached to the main body case 20 of the main body portion 3 in a state where the clamp arm 31 is rotatable with respect to the main body portion 3 around a fulcrum provided at a base end portion (lower end portion in the figure). It is arranged. Further, each clamp arm 31 is opened and closed with respect to each operation button 20a disposed on the main body case 20 (the upper ends in the figure and the lower ends in the figure). Is rotated so as to contact and separate.

  As shown in FIG. 3, the hall element 32 is disposed at the proximal end portion of one clamp arm 31. The Hall element 32 detects a magnetic field generated when each core 31a of each clamp arm 31 is excited and outputs a detection signal Sd (DC voltage).

  In this case, in the configuration of the clamp sensor 3 provided with the core 31a and the hall element 32, as shown in FIG. 4, each end of each clamp arm 31 is joined to form an annular body surrounding the electric wire 100. In the state, the Hall element 32 detects a static magnetic field (static magnetic field generated in each core 31a excited by the static magnetic field) as a detected amount generated when a direct current flows through the electric wire 100, and outputs a detection signal Sd. . Therefore, in the current measuring device 1, it is possible to measure the direct current flowing through the electric wire 100 by using the clamp sensor 3.

  The flexible sensor 4 corresponds to a second sensor, and includes a sensor cable 41, a connecting portion 42, and a signal cable 43 as shown in FIG.

  The sensor cable 41 is formed in a cable shape having flexibility. Specifically, as shown in FIG. 5, the sensor cable 41 includes a flexible core 41a, a coil 41b, and a jacket (sheath) 41c.

  The flexible core 41a is a flexible core (magnetic core), and is formed by combining a magnetic material and a flexible (flexible) resin. As an example, metallic magnetic materials such as silicon steel, iron, permalloy, sendust and permendur, and ferrite magnetic materials such as spinel ferrite and hexagonal ferrite are used in powder, granular, fibrous, and pellet forms. Further, it is formed by mixing one in a chip-like state with pellets of resin such as soft vinyl chloride, polyethylene and urethane, and injection-molding this mixture into a cable shape.

  As shown in FIG. 5, the coil 41b is formed by winding a covered electric wire around the flexible core 41a, detects an alternating magnetic field generated in the flexible core 41a, and outputs a detection signal Sd (alternating current).

  The jacket 41c is formed of a flexible insulating material (for example, soft vinyl chloride or polyethylene), and covers the flexible core 41a and the coil 41b.

  As shown in FIG. 5, an insertion member 41 d is attached to one end of the sensor cable 41.

  As shown in FIGS. 5 and 6, the connecting portion 42 has an insertion port 42 a for inserting an insertion member 41 d attached to one end portion of the sensor cable 41, and one end portion and the other end portion of the sensor cable 41. Are connected (joined) and disconnected (joined).

  The signal cable 43 is a cable for transmitting the detection signal Sd output from the coil 41b to the processing unit 23 of the main body 2 and, as shown in FIG. 3, via a connector 43a attached to the distal end. And connected to the connector 20b of the main body 2.

  In this case, in the flexible sensor 4 including the flexible core 41a and the coil 41b made of soft magnetic material and having flexibility, both ends of the sensor cable 41 are connected (joined) as shown in FIG. In the state of forming an annular body surrounding the electric wire 100, an AC magnetic field as a detected amount generated when an AC current flows through the electric wire 100 is detected and a detection signal Sd is output. Therefore, in the current measuring apparatus 1, it is possible to measure the alternating current flowing through the electric wire 100 by using the clamp sensor 3.

  Moreover, since this flexible sensor 4 has the coil 41b formed by winding a covered electric wire around the flexible core 41a, the flexible core 41a is excited by an alternating magnetic field generated when an alternating current flows through the electric wire 100. The coil 41b detects an alternating magnetic field generated in the excited flexible core 41a. For this reason, in this flexible sensor 4, compared with a flexible sensor that does not have a flexible core 41a, such as a Rogowski coil, it is possible to reliably detect an AC magnetic field that is generated when an AC current flows through the electric wire 100. As a result, the detection accuracy can be sufficiently improved.

  Next, a method for measuring the current flowing through the electric wire 100 using the current measuring device 1 will be described with reference to the drawings.

  The current measuring device 1 includes two sensors, a clamp sensor 3 and a flexible sensor 4, and the two sensors can be used properly according to the measurement mode (according to the amount to be measured). For example, when measuring a direct current flowing through the electric wire 100, the clamp sensor 3 is used. In the measurement using the clamp sensor 3, the power switch 22a in the operation unit 22 provided in the main body 2 is operated, and then the dial 22b of the operation unit 22 is operated to set the measurement mode to the direct current measurement. Set to mode.

  Subsequently, the electric wire 100 is clamped by each clamp arm 31 of the clamp sensor 3. Specifically, as shown in FIG. 3, the two operation buttons 20 a disposed on the main body 2 are pushed. At this time, each clamp arm 31 is rotated in a direction in which each end portion is separated (opened) around a fulcrum provided at the base end portion.

  Next, the electric wire 100 is passed through the gaps between the tip portions of the clamp arms 31, and then the push of each operation button 20a is released. At this time, each clamp arm 31 is rotated by the biasing force of the biasing member (not shown), so that the ends of the clamp arms 31 are joined to each other as shown in FIG. An annular body is formed, and the electric wire 100 is surrounded (clamped) by the annular body.

  In this case, when a direct current flows through the electric wire 100, the Hall element 32 detects the static magnetic field generated in each core 31a excited by the static magnetic field generated by the direct current, and outputs the detection signal Sd. Next, the processing unit 23 measures the current value of the direct current flowing through the electric wire 100 based on the detection signal Sd (detected amount detected by the clamp sensor 3), and then displays the measured current value on the display unit 21. Display.

  Next, when the measurement is finished, the respective operation buttons 20a are pushed in, thereby separating the respective distal end portions of the respective clamp arms 31 from each other, and subsequently, the clamping of the electric wire 100 by the respective clamp arms 31 is released.

  On the other hand, the flexible sensor 4 is used when measuring the alternating current flowing through the electric wire 100. In the measurement using the flexible sensor 4, the connector 43 a attached to the tip of the signal cable 43 of the flexible sensor 4 is connected to the connector 20 b of the main body 2, and then the dial 22 b of the operation unit 22 is operated. Set the measurement mode to AC current measurement mode.

  Next, the flexible sensor 4 surrounds the periphery of the electric wire 100. Specifically, as shown in FIG. 5, the insertion member 41 d attached to one end of the sensor cable 41 is pulled out from the insertion port 42 a of the connecting portion 42, and then the electric wire 100 is surrounded by the sensor cable 41. Next, as shown in FIG. 6, the insertion member 41 d attached to one end of the sensor cable 41 is inserted into the insertion port 42 a of the connecting portion 42, and the one end and the other end of the sensor cable 41 are connected ( Bonding). At this time, the sensor cable 41 forms an annular body, and the electric wire 100 is surrounded by the annular body.

  In this case, when an alternating current is flowing through the electric wire 100, the flexible core 41a is excited by an alternating magnetic field generated by the alternating current, and the coil 41b detects the alternating magnetic field generated in the excited flexible core 41a and generates the detection signal Sd. Output. Subsequently, the processing unit 23 inputs the detection signal Sd via the signal cable 43 and measures the current value of the alternating current flowing through the electric wire 100 based on the detection signal Sd (the detected amount detected by the flexible sensor 4). To do. Next, the processing unit 23 causes the display unit 21 to display the measured current value.

  In this case, since the flexible sensor 4 has the coil 41b formed by winding the covered electric wire around the flexible core 41a as described above, an AC magnetic field generated when an AC current flows through the electric wire 100 is used. As a result of the coil 41b detecting the alternating magnetic field generated in the excited flexible core 41a when the flexible core 41a is excited, it is possible to reliably detect the alternating magnetic field as a detected amount generated when an alternating current flows through the electric wire 100. It has become. For this reason, in the current measuring apparatus 1 provided with this flexible sensor 4, the flexible sensor 4 which has the flexibility which can be used by changing according to the shape of the electric wire 100, the presence of an obstacle around the electric wire 100, etc. It is possible to sufficiently improve the measurement accuracy of the alternating current flowing through the electric wire 100 while maintaining the above characteristics.

  Subsequently, when the measurement is completed, the connection portion 42 is pulled out from the insertion port 42a, and then the surrounding of the electric wire 100 by the sensor cable 41 is released.

  As described above, in the current measuring device 1, the clamp sensor 3 disposed in the main body 2 and the flexible sensor 4 formed separately from the main body 2 and formed into a flexible cable shape. The flexible sensor 4 includes a flexible core 41a having flexibility and formed of a magnetic material. For this reason, according to this electric current measurement apparatus 1, while being able to use the clamp sensor 3 and the flexible sensor 4 properly according to a measurement aspect, according to the shape of the electric wire 100, the presence of the obstruction around the electric wire 100, etc. It is possible to sufficiently improve the measurement accuracy when measuring the amount to be measured using the flexible sensor 4 having flexibility that can be used by being deformed.

  Moreover, according to this electric current measuring apparatus 1, since the 2nd sensor was comprised including the coil 41b formed with the covering electric wire wound around the flexible core 41a, the alternating current which flows into the electric wire 100 is made into a flexible sensor. The measurement accuracy when measuring using 4 can be sufficiently improved.

  Note that the configuration of the current measuring device is not limited to the above configuration. For example, instead of the above-described flexible sensor 4, a flexible sensor 104 shown in FIG. 7 can be employed. In addition, in the following description, the same code | symbol is attached | subjected about the component similar to the flexible sensor 4, and the overlapping description is abbreviate | omitted. As shown in the figure, the flexible sensor 104 is disposed on the flexible core 41a, the outer cover 41c that covers the flexible core 41a, and the end of the flexible core 41a (one example in or near the core). And a Hall element 41e as a magnetic detection element for detecting a static magnetic field.

  In the flexible sensor 104, the provision of the flexible core 41a makes it possible to reliably detect a static magnetic field as a detected amount generated by a direct current flowing through the electric wire 100. Therefore, also in the current measuring apparatus 1 including the flexible sensor 104, the clamp sensor 3 and the flexible sensor 104 can be properly used according to the measurement mode, and the shape of the electric wire 100, the presence of obstacles around the electric wire 100, and the like. Therefore, it is possible to sufficiently improve the measurement accuracy when measuring the amount to be measured using the flexible sensor 104 having flexibility that can be used by being deformed according to the above.

  Further, the flexible core 41a formed by combining the magnetic material and the flexible resin has been described as an example, but the configuration of the flexible core 41a is not limited thereto. For example, inside a flexible cylinder (a cylinder formed of a soft resin), any of strips (powder, granules, pellets, and chips) formed of a magnetic material as a magnetic material It is also possible to employ a flexible core 41a configured by filling a magnetic material in such a state.

  Moreover, it replaces with the above-mentioned clamp sensor 3, It equips with a pair of clamp arms which have a core and the coil (core coil) formed by winding a covering electric wire around a core, and it is the structure which can detect an alternating current magnetic field The clamp sensor 3 that has been used can also be employed. Furthermore, it is also possible to employ a clamp sensor 3 that includes a pair of clamp arms each having a coil (air core coil) that does not have a core and is configured to detect an alternating magnetic field.

  In the above example, the Hall element is used as the magnetic detection element. However, instead of the Hall element, a flux gate type magnetic detection element as another example of the magnetic detection element may be used.

DESCRIPTION OF SYMBOLS 1 Current measuring device 2 Main body part 3 Clamp sensor 4 Flexible sensor 20a Operation button 23 Processing part 31 Clamp arm 41 Sensor cable 41a Flexible core 41b Coil 41d Hall element 100 Electric wire Sd Detection signal

Claims (3)

An annular body composed of a main body part and a pair of clamp arms, each end part of each clamp arm being detachably arranged by opening / closing operation, and each end part joined to surround the measurement object The first sensor for detecting the amount to be detected caused by the current flowing through the measurement object in the state of the body, and the body portion are configured separately from each other, and are formed in a flexible cable shape with both ends. And a second sensor for detecting the detected amount in a state of forming an annular body surrounding the measuring object, and a measuring unit disposed in the main body portion and measuring the current based on the detected amount A current measuring device comprising:
The second sensor is a current measuring device configured to include a flexible core formed of a magnetic material.   The current measuring apparatus according to claim 1, wherein the second sensor includes a coil formed of a covered electric wire wound around the core.   The current measurement device according to claim 1, wherein the second sensor includes a magnetic detection element disposed in either the core or the vicinity of the core.

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