JP2007093469A - Current measurement device and current measurement system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely measure current, even at a location where a power source cord 1 is installed and has no spatial margin. <P>SOLUTION: A current measurement device 3 comprises a clamp sensor 5 attached surrounding the power source cord 1, a current measurement part 3 for measuring the current made to flow in the power source cord 1, on the basis of a detection value from the clamp sensor 5 by being connected to the clamp sensor 5, and an RFID tag 7 for transmitting the measured result at the current measurement part 3, by being connected to the current measurement part 3. A current measurement system comprises the current measurement device 3, and a RFID reader for performing transmission and reception of a signal with the RFID tag 7 of the current measuring device 3 and supply of electric power. The RFID reader is provided with the input means of a current measurement instruction and ID information. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a current measuring device and a current measuring system for measuring a current flowing through a conductor in a live line state.

  In general, a clamp-type ammeter has a configuration as described in Patent Document 1. By attaching the clamp sensor of the clamp type ammeter so as to surround the conductor, the current flowing through the conductor can be measured without cutting the circuit in a live line state.

  However, the clamp-type ammeter disclosed in Patent Document 1 is mainly composed of a clamp sensor and an instrument body, and thus the apparatus is large, so that it is difficult to use it in a narrow place where there is no space.

A configuration for solving this problem is shown in Non-Patent Document 1. Here, a clamp probe is provided, and a current detected by taking in a value detected by the clamp probe by the instrument body.
JP 2003-302423 A Supervised by Hiroshi Takahashi, published by Ohm Co., Ltd.

  However, even in the configuration of Non-Patent Document 1, measurement is difficult in a place where there is not enough space. That is, even in the non-patent document 1, since the clamp probe part and the instrument body part must be physically integrated or at least electrically connected, the clamp probe part is inserted into a narrow space. It was not easy to attach to a conductor, and it was difficult to measure in a place where there was not enough space.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a current measuring device and a current measuring system capable of reliably performing current measurement even in a place where there is not enough space.

  In order to solve the above problems, a current measuring device according to the present invention is a current measuring device for measuring a current flowing through a conductor, and includes a clamp sensor that is attached to surround the conductor, and a clamp sensor connected to the clamp sensor. A current measuring unit that measures a current flowing through the conductor based on a detected value from the RFID tag, and an RFID tag that is connected to the current measuring unit and transmits a measurement result of the current measuring unit. To do.

  In addition, the current measurement system of the present invention includes the current measurement device described above and an RFID reader that transmits and receives signals between the RFID tag of the current measurement device and supplies power by electromagnetic energy without contact. It is characterized by having.

  In the current measuring device, a clamp sensor is attached to the conductor, a current measuring unit measures a current flowing through the conductor based on a detection value from the clamp sensor, and transmits the measurement result using an RFID tag. Thus, even in a place where there is no space, current measurement can be reliably performed by incorporating the current measurement device in advance and transmitting measurement information by wireless communication.

  In addition, since the current measurement system is configured to include the current measurement device and the RFID reader that performs transmission and reception of signals and supply of electric power by electromagnetic energy between the RFID tag of the current measurement device, the current measurement device is Even if it is built in the vicinity of the conductor, no maintenance is required, and current measurement can be performed by supplying power to the current measurement device with an RFID reader and receiving the measurement results only during current measurement. it can.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings. Recent electronic devices are used in various fields. Various electronic devices have come to be used in factories and households. And the necessity to manage the electric current which flows into such an individual electronic device has also increased. On the other hand, when electronic devices are complicated and large-scale devices, or various electronic devices are arranged in various ways, conductors to be measured such as power supply wiring are arranged in a place where there is not enough space. There are many things to do. The current measuring device and the current measuring system of the present invention are improved so that current can be reliably measured in this manner. Hereinafter, a specific configuration will be described.

[First embodiment]
The first embodiment of the present invention will be described below. FIG. 1 is a schematic configuration diagram showing a current measuring apparatus according to the present embodiment, FIG. 2 is a block diagram showing a configuration of an RFID tag, and FIG. 3 is a configuration diagram showing a current measuring system.

  1 in FIG. 1 indicates a power cord as a conductor to be measured. The power cord 1 is composed of two electric wires, and a plug 2 is attached to the end thereof.

  3 in the figure indicates a current measuring device. The current measuring device 3 is a device for measuring the current of the power cord 1. The current measuring device 3 includes a clamp sensor 5, a current measuring unit 6, and an RFID tag 7.

  The clamp sensor 5 includes a ring-shaped iron core 9 attached so as to surround one of the two electric wires of the power cord 1, and a conductive wire 10 wound around the iron core 9. Thereby, the magnetic flux in the iron core 9 changes according to the magnitude of the current flowing through the power cord 1, and the induced electromotive force generated in the conducting wire 10 changes. That is, the current of the power cord 1 and the induced electromotive force generated in the conducting wire 10 are changed in proportion. As the clamp sensor 5, another method may be used. For example, a sensor using a Hall element utilizing the Hall effect may be used.

  The current measuring unit 6 is a part that measures the current flowing through the power cord 1 based on the detection value from the clamp sensor 5. The current measuring unit 6 includes a bridge circuit 11 and a resistor 12. One end of the bridge circuit 11 is connected to the lead wire 10 of the clamp sensor 5, and the other end is connected to the lead wire 13 on the RFID tag 7 side. The resistor 12 is connected to the conducting wire 13. The current measuring unit 6 has a minimum configuration including only the bridge circuit 11 and the resistor 12 to reduce the size.

  The RFID tag 7 is a part that is connected to the current measuring unit 6 and transmits a current value measured by the current measuring unit 6. As shown in FIG. 2, the RFID tag 7 includes a processing unit 15 and an antenna 16.

  The processing unit 15 is a processing unit for specifying the current value in the power cord 1 from the detection value of the current measuring unit 6. The processing unit 15 includes an RFID transceiver unit 18, a nonvolatile memory 19, an analog interface unit 20, and a digital I / O 21.

  The RFID transmission / reception unit 18 includes a CPU, a wireless unit, and the like, and is a part that executes processing such as transmission / reception. The RFID transceiver 18 demodulates the radio signal captured by the antenna 16 into a digital signal, analyzes the digital signal, executes processing according to a question from the RFID reader 23 described later, and forms a response signal. The response signal is modulated and returned from the antenna 16. The interrogation signal from the RFID reader 23 is an ID symbol such as a current value at the power cord 1 or an ID number assigned to the RFID tag 7 in the current measuring device 3.

  The RFID transmitter / receiver 18 is a power supply unit (not shown) having a function of obtaining power necessary for the operation of the RFID transmitter / receiver 18 and the nonvolatile memory 19 from the radio signal captured by the antenna 16. And is supplied to each unit as an operating power source.

  The nonvolatile memory 19 is composed of, for example, an EEPROM or an FeRAM, and stores data such as an ID assigned to the nonvolatile memory 19 and a program executed by the RFID transceiver unit 18. Also, management information may be recorded. This management information includes the previous access date and time, the previous current value, and the like.

  The analog interface unit 20 is composed of, for example, a comparator circuit or an A / D converter circuit, and converts an analog change in value in the current measurement unit 6 into a digital quantity.

  The digital I / O 21 is an element for connecting to an external expansion element. Here, an identification lamp (not shown) is connected to the digital I / O 21. That is, an identification lamp is connected as a visual display means for individual identification. An LED or the like is used as the identification lamp. When an ID for identifying a desired current measuring device 3 and an identification lamp lighting command are transmitted from the RFID reader 23, the RFID transmitter / receiver 18 of the current measuring device 3 to which the ID is assigned sends the identification lamp lighting command and Upon receiving the power supply, the identification lamp is turned on via the digital I / O 21 so that the desired current measuring device 3 can be quickly identified.

  The antenna 16 is a transmission / reception shared antenna, receives question information from the RFID reader 23, and transmits a response to the question. Further, it has a function of receiving power supply from the RFID reader 23.

  The current measuring device 3 including the clamp sensor 5, the current measuring unit 6 and the RFID tag 7 is integrally attached so as to surround the power cord 1 as shown in FIG. Here, the current measuring device 3 includes the RFID tag 7 and wirelessly transmits the current value measured by the current measuring unit 6 to the RFID reader 23, so that the current measuring unit 6 has a minimum configuration, and current measurement is performed. By significantly downsizing the device 3, it is integrally attached to the power cord 1 without being bulky as shown in FIG.

  The RFID reader 23 is a device that exchanges information wirelessly with the RFID tag 7. The RFID reader 23 includes a display unit 24 (see FIG. 5), an operation button 25 (see FIG. 5), a processing unit (not shown), and an antenna (not shown). The display unit 24 is a part that displays information such as a current value. The operation button 25 is a button for performing a current measurement instruction, inputting ID information, and the like. That is, the operation button 25 has at least functions as a current measurement instruction unit and an ID information input unit. The processing unit exchanges information with the RFID tag 7 via the antenna to process the received information and display the information on the display unit 24. In response to an instruction from the operation button 25, the RFID This is a part for transmitting an instruction signal to the tag 7. Further, the processing unit supplies power to the RFID tag 7 via the antenna.

  As a result, bulky parts such as a display unit, an operation unit, and a power source are provided on the RFID reader 23 side, and the current measuring device 3 side has a minimum configuration. A small current measuring device 3 that is integrally attached to the power cord 1 and an RFID reader 23 that incorporates bulky components and exchanges information with the current measuring device 3 by wireless communication constitute a current measuring system. It is composed.

  The current measurement system configured as described above is used as follows.

  The current measuring device 3 is integrally attached to the power cord 1 in advance. In this state, the current measuring device 3 is not particularly bulky and normal power supply is performed.

  When measuring the current of the power cord 1, the operation button 25 of the RFID reader 23 is operated to request current measurement. Accordingly, the processing unit of the RFID reader 23 transmits a current measurement request signal to the RFID tag 7 of the current measuring device 3 via the antenna. At the same time, power is supplied.

  The RFID tag 7 operates upon receiving power supply, measures the current of the power cord 1 with the clamp sensor 5 and the current measurement unit 6 based on the current measurement request signal, and transmits information on the current value with the RFID tag 7. To do.

  Upon receiving this signal, the RFID reader 23 displays the current value on the display unit 24 via the antenna and the treatment unit.

  When it is desired to turn on the identification lamp, the operation button 25 of the RFID reader 23 is used to turn on the identification lamp and supply power. As a result, the RFID tag 7 is supplied with power and turns on the identification lamp. This lighting of the identification lamp is particularly effective when there are a plurality of power cords 1. A specific aspect will be described in detail in the third embodiment.

  As described above, the current measuring device 3 and the RFID reader 23 can be separated, and the current measuring device 3 can be greatly downsized with the downsizing of the RFID tag 7. As a result, the current measuring device 3 can be securely attached to the power cord 1 even in a narrow space where there is no room.

  In addition, since the current measuring device 3 does not have a power source and operates by receiving power supplied from the RFID reader 23, it is not necessary to provide a bulky power source, and the current measuring device 3 can be further downsized. .

  As a result, the current measuring device 3 and the power cord 1 can be integrally formed, and the power cord 1 is used as a normal power cord when not measuring, and the RFID reader 23 is only brought close when measuring the power. Get better. As a result, current measurement can be reliably performed even in a narrow space where there is no space.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. Since the overall configuration of the current measurement system according to the present embodiment is substantially the same as that of the current measurement system according to the first embodiment, the same members are denoted by the same reference numerals and description thereof is omitted here.

  The current measurement system of the present embodiment is characterized by the iron core of the clamp sensor 5. In the first embodiment, the iron core 9 of the clamp sensor 5 is ring-shaped and incorporated in the power cord 1 in advance. However, as shown in FIG. 4, an annular iron core 27 is configured to be opened and closed by a hinge 28. Yes. That is, the iron core 27 is configured to be able to be opened and closed in half, and by closing it, one of the two electric wires of the power cord 1 can be enclosed and attached.

  As a result, the current measuring device 3 and the power cord 1 need not be integrally formed in advance. As a result, it can be arbitrarily incorporated into an existing power cord without cutting the circuit. As a result, in addition to the effects of the first embodiment, it is possible to reliably perform current measurement even on an existing power cord that is already disposed in a narrow space where there is not enough space. .

[Third Embodiment]
Next, a third embodiment of the present invention will be described. Since the overall configuration of the current measurement system according to the present embodiment is substantially the same as that of the current measurement system according to the first embodiment, the same members are denoted by the same reference numerals and description thereof is omitted here.

  The current measurement system according to the present embodiment is an example in the case of having a plurality of power cords 1. Specifically, as shown in FIG. 5, when a plurality (three in FIG. 5) of power cords 1 are provided, it is necessary to specify which power cord 1 is to be measured. For this reason, the ID number is described on each current measuring device 3 with the current measuring device 3 attached to each power cord 1. That is, an ID number as an ID symbol is written on the surface position of each current measuring device 3 that can be recognized from the outside. The ID symbol may be a symbol other than a number. In addition, 30 is an outlet.

  Further, as described in the first embodiment, the RFID reader 23 can input an ID number from the operation button 25.

  With the above configuration, when the current measurement of a specific power cord 1 is performed, the ID number of the power cord 1 is input from the operation button 25 of the RFID reader 23. At the same time, a current measurement instruction is input from the operation button 25.

  Thereby, the RFID reader 23 and the RFID tag 7 of the current measuring device 3 attached to the specific power cord 1 exchange signals to measure the current of the specific power cord 1.

  Instead of describing the ID number, each power cord 1 may be specified by turning on an identification lamp connected to the digital I / O 21. In this case, an identification lamp lighting instruction is input from the operation button 25 of the RFID reader 23 together with the ID number. At the same time, a current measurement instruction may be input.

  Thereby, even when a plurality of power cords 1 are connected to the table tap, that is, when a plurality of current measuring devices 3 are close to each other, the desired power cord 1 is specified and the current is measured. can do.

[Modification]
In the first embodiment, the power cord 1 has been described as an example of the conductor to be measured. However, the present invention is not limited to the power cord 1 and a conductor through which a current passes and the current needs to be measured. It can be applied to all.

  Moreover, in the said 1st Embodiment, although the iron core 9 was made into the ring shape and was integrally provided in the power cord 1, you may make the whole into a half member. That is, two halved members (not shown) formed in a cylindrical shape so as to surround the power cord 1 and hinges provided between the halved members so as to be openable and closable (Not shown), and the clamp sensor 5, the current measuring unit 6, and the RFID tag 7 may be integrally incorporated in each half member. Also in this case, the same operations and effects as the above embodiment can be achieved.

  In the first embodiment, the current measuring device 3 is incorporated in the power cord 1. However, the current measuring device 3 may be incorporated in a member disposed on the wiring of the power cord 1. For example, you may incorporate in the plug 2 in FIG. You may incorporate in the outlet 30 in FIG. Further, the power cord 1 may be integrated into an extension cord (not shown). In the case of this extension cord, it may be incorporated in the cord or plug. In these cases, the same operations and effects as the above-described embodiments can be obtained.

It is a lineblock diagram showing the current measuring device concerning a 1st embodiment of the present invention. It is a block diagram which shows the RFID tag of the electric current measurement apparatus which concerns on the 1st Embodiment of this invention. It is a lineblock diagram showing the current measurement system concerning a 1st embodiment of the present invention. It is a side view which shows the iron core of the clamp sensor which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the electric current measurement system which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

1: power cord, 2: plug, 3: current measuring device, 5: clamp sensor, 6: current measuring unit, 7: RFID tag, 9: iron core, 10: conductor, 11: bridge circuit, 12: resistance, 13: Conductor, 15: processing unit, 16: antenna, 18: RFID transceiver unit, 19: nonvolatile memory, 20: analog interface unit, 21: digital I / O, 23: RFID reader, 24: display unit, 25: operation button .

Claims (12)

A current measuring device for measuring a current flowing through a conductor,
A clamp sensor that is mounted surrounding the conductor;
A current measurement unit that is connected to the clamp sensor and measures a current flowing through the conductor based on a detection value from the clamp sensor;
A current measuring device comprising an RFID tag connected to the current measuring unit and transmitting a measurement result of the current measuring unit. The current measuring device according to claim 1,
The RFID tag includes an ID for distinguishing from others, and transmits the ID information together with the measurement result. In the current measuring device according to claim 1 or 2,
A current measuring device, wherein the clamp sensor is configured to be able to be opened and closed in half, and is attached so as to surround the conductor by being closed. The current measuring device according to any one of claims 1 to 3,
A current measuring device, wherein the clamp sensor, the current measuring unit, and the RFID tag are integrally incorporated in a member disposed on the conductor wiring. The current measuring device according to claim 4,
A current measuring device, wherein the member disposed on the conductor wiring is an outlet. The current measuring device according to claim 4,
A current measuring device, wherein the member disposed on the conductor wiring is a plug inserted into an outlet. The current measuring device according to claim 4,
The current measuring device, wherein the member disposed on the conductor wiring is an extension cord. The current measuring device according to claim 1,
Two half members formed so as to surround the conductor, and a hinge that supports each half member so as to be openable and closable,
A current measuring apparatus comprising the clamp sensor, a current measuring unit and an RFID tag incorporated in the two halved members. In the current measuring device according to any one of claims 1 to 8,
A current measuring device, wherein the RFID tag is supplied with electric power from the outside through a built-in antenna. The current measuring device according to any one of claims 1 to 9,
A current measuring apparatus characterized in that an ID symbol is described at a position that can be recognized from the outside. The current measuring device according to any one of claims 1 to 10,
A current measurement system comprising: an RFID reader that transmits and receives signals and supplies power to the RFID tag of the current measurement device. The current measurement system according to claim 11,
A current measurement system, wherein the RFID reader comprises an ID information input means.

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