JP2010169600A - Measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately measure the effective value on a contact current of an AC waveform on which a DC component is superimposed. <P>SOLUTION: A processing part 7 executes: a measuring processing for measuring a DC component Idc and an AC component Iac from waveform data D1 of a contact current Itc flowing in a human body simulation circuit 2; an effective value calculation processing for calculating q sinusoidal wave effective value Iev of the contact current Itc, by dividing a swinging width Ipp of the contact current Itc calculated from the waveform data D1 by a value (2×√2), when each component Idc, Iac is equal to or more than each reference value Ir1, Ir2 together, and a duration T1 of the contact current Itc is over m times a cardiac cycle Tc, and calculating a sinusoidal wave effective value Iev, by dividing the maximum absolute value Ip of a peak value of the contact current Itc calculated from the waveform data D1 by a value of Ip/√2, when each component Idc, Iac is equal to or more than each reference value Ir1, Ir2 together, and the duration T1 is below n times the cardiac cycle Tc; and an output processing for outputting the sine wave effective value Iev to an output part 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a current measuring device that measures a contact current of a device to be measured.

  As this type of current measuring device, a current measuring device disclosed as a conventional technique in Patent Document 1 below is known. This current measuring device is provided with a human body simulation circuit, and in accordance with “Detailed Regulations for Handling Ordinances for Establishing Technical Standards for Electrical Appliances in the Electrical Appliance and Material Safety Law” and “International Standards of IEC 60335-1: 1994”. Measure the leakage current between any one of the two AC power lines (hereinafter also referred to as “power lines”) connected to the (measurement target device) and the exterior (exposed charging part) of the electrical appliance. It is configured to be possible.

JP 2004-138565 A (second page)

  By the way, in addition to the above-mentioned standard for leakage current, there is a standard for contact current (IEC60990 “Measurement method for contact current and protective conductor current”), and a current measuring device capable of measuring contact current based on this standard is also available. Various developments have been made. On the other hand, since the contact current with a waveform not defined in any of the above standards (AC current including the DC component shown in FIGS. 3 and 4) also affects the human body, its effective value can be measured accurately. Is preferred. However, both the current measuring device proposed by the applicant of the present application and the current measuring device for measuring the contact current described above have a contact current having a waveform as shown in FIGS. Therefore, there is a problem that the effective value of the contact current cannot be measured accurately.

  The present invention has been made to solve such a problem, and a main object of the present invention is to provide a current measuring device capable of accurately measuring an effective value of a contact current having an AC waveform on which a DC component is superimposed.

  In order to achieve the above object, a current measuring device according to claim 1 is provided between a human body simulation circuit, an AC power supply line including a ground wire and an exterior of a measuring target device, and each of two measuring target devices. When the human body simulation circuit is connected to any of the leakage current measuring terminals, the voltage between both ends generated between both ends of the predetermined element constituting the human body simulation circuit due to the contact current flowing through the human body simulation circuit A current measuring device including a processing unit that measures an effective value of the contact current based on the A / D conversion unit that samples the voltage between both ends and generates waveform data about the contact current; and an output A measurement process for measuring the direct current component and the alternating current component of the contact current based on the waveform data, and the absolute value of the direct current component and the magnitude of the alternating current component are both Therefore, when the duration of the contact current exceeds m times the cardiac cycle (m is a positive number), the fluctuation width Ipp of the contact current is calculated based on the waveform data. And the sine wave effective value of the contact current is calculated by dividing the fluctuation width Ipp by the value (2 × √2), and the absolute value of the DC component and the magnitude of the AC component are both greater than or equal to the reference value. When the duration is less than n times the cardiac cycle (n is a positive number less than m), the maximum absolute value Ip of the peak value of the contact current is calculated based on the waveform data and the maximum absolute An effective value calculation process for calculating the sine wave effective value of the contact current by dividing the value Ip by the value Ip / √2, and causing the output unit to output the sine wave effective value calculated in the effective value calculation process Execute output processing .

  The current measurement device according to claim 2 is the current measurement device according to claim 1, wherein the output unit is configured by a display device, and the processing unit is the sine wave effective calculated in the effective value calculation processing. The value is compared with a predetermined reference effective value, and the comparison result is displayed on the display device.

  According to the current measuring device of claim 1, the absolute value of the direct current component and the magnitude of the alternating current component are equal to or greater than a predetermined reference value for each, and the duration of the contact current is m times the cardiac cycle. , The sine wave effective value of the contact current can be calculated by calculating the oscillating width Ipp of the contact current based on the waveform data and dividing the oscillating width Ipp by the value (2 × √2). When the absolute value of the current and the magnitude of the alternating current component are both greater than or equal to the reference value and the duration is less than n times the cardiac cycle, the maximum absolute value Ip of the peak value of the contact current is calculated based on the waveform data. In addition, the sine wave effective value of the contact current can be calculated by dividing the maximum absolute value Ip by the value Ip / √2, so that the measurement of the sine wave effective value for the contact current that is an alternating current on which the direct current is superimposed; Evaluation IEC60479-2 can be carried out in accordance with the standard. Further, according to this current measuring device, based on the waveform data, whether or not the contact current is an alternating current superimposed with a direct current, and further, how long the duration of the contact current is based on the cardiac cycle. Since the sine wave effective value is automatically calculated and the sine wave effective value is automatically calculated, the sine wave effective value defined in IEC60479-2 can be calculated accurately and in a short time.

  According to the current measuring device of claim 2, since the comparison result between the calculated sine wave effective value and the reference effective value defined in advance is displayed on the output unit configured by the display device, the direct current is It is possible to reliably recognize the result of automatically evaluating the sine wave effective value for the contact current that is the superimposed alternating current according to the IEC60479-2 standard.

1 is a block diagram showing a configuration of a current measuring device 1. FIG. It is a circuit diagram of the human body simulation circuit 2 in FIG. It is a wave form diagram of contact current Itc. It is another wave form diagram of contact current Itc. It is a block diagram which shows the structure of 1 A of current measuring devices.

  Hereinafter, an embodiment of a current measuring device according to the present invention will be described with reference to the accompanying drawings.

  First, the configuration of the current measuring device 1 will be described.

  As shown in FIG. 1, the current measuring device 1 includes a human body simulation circuit (simulated human body impedance circuit) 2, an A / D conversion unit 3, a switch circuit 4, an input terminal unit 5, an output terminal unit 6, a processing unit 7, and a memory. Unit 8, operation unit 9, and output unit 10, and the sine wave effective value of the contact current Itc for the measurement target device 11 (in this example, as described later, an equivalent sine wave current obtained by an expression defined by IEC 60479-2) The effective value) can be measured. Further, in the current measuring device 1, the human body simulation circuit 2, the A / D conversion unit 3, the switch circuit 4, the processing unit 7 and the storage unit 8 are disposed in one housing 1a, and the input terminal unit 5 and the output The terminal part 6, the operation part 9, and the output part 10 are attached to the wall surface of the housing 1a.

  The human body simulation circuit 2 uses at least one of a known circuit (for example, a circuit defined for measuring a contact current in IEC 60990) configured by only a resistive element or a combination of a resistive element and a capacitive element. Configured. In this example, as an example, the human body simulation circuit 2 is configured by combining three resistance elements (resistances R1 to R3) and two capacitance elements (capacitors C1 and C2) as shown in FIG. Specifically, in the human body simulation circuit 2, two resistors R1 and R2 are connected in series in this order between a terminal (current input terminal) A and a terminal (reference terminal) B, and a capacitor C1 is connected to the resistor R1. Connected in parallel. Further, a low-pass filter circuit including a resistor R3 and a capacitor C2 is connected between both ends of the resistor R2 (a predetermined element in the present invention). A terminal (voltage output terminal) C is connected to a connection point between the resistor R3 and the capacitor C2. The terminal A of the human body simulation circuit 2 is connected to a connector 12 provided on the housing 1a. The detection probe 2a is detachably connected to the connector 12. With this configuration, in this human body simulation circuit 2, the contact current Itc flowing from the detection probe 2a through the terminal A to the terminal B is converted to the voltage Vtc by the resistor R2, and the voltage Vtc (voltage across the present invention) is converted to Output from the terminal C is possible via a low-pass filter circuit.

  The A / D conversion unit 3 samples the voltage Vtc output from the human body simulation circuit 2 at a predetermined period, thereby showing a voltage waveform of the voltage Vtc (that is, a waveform of the contact current Itc converted to the voltage Vtc). Data D1 is generated and output. As an example, the switch circuit 4 is configured by combining a plurality of relays. The switch circuit 4 is disposed between the AC power supply lines AC1 and AC2 including the ground wire G and the human body simulation circuit 2, and the connection / disconnection state of each relay according to the control signal S1 output from the processing unit 7. Is controlled so that the human body simulation circuit 2 is connected to any one of the ground line G, the AC power supply line AC1, and the AC power supply line AC2 (any one of the AC power supply lines including the ground line G). Connect terminal B.

  As an example, the input terminal portion 5 includes a connector (for example, an AC inlet) including a ground connection terminal and a pair of AC input terminals. As an example, the output terminal portion 6 includes a connector (for example, an AC outlet) including a ground connection terminal and a pair of AC output terminals, and the ground connection terminal is connected to the ground connection terminal of the input terminal portion 5. A pair of AC output terminals are connected to a pair of AC input terminals of the input terminal portion 5. The measurement target device 11 has a power cord (including a ground wire) 13 connected to the output terminal unit 6 and is supplied with an AC power source Vac via the current measuring device 1 and connected to the ground.

  The processing unit 7 includes a CPU as an example, and executes measurement processing, effective value calculation processing, comparison processing, output processing, and control processing. Specifically, in the measurement process, the processing unit 7 determines the absolute value of the direct current component Idc (the absolute value of the level of the direct current component Idc) and the amplitude of the alternating current component Iac (the present invention) for the contact current Itc based on the waveform data D1. Measure the magnitude of the AC component Iac at. Further, in the effective value calculation process, the processing unit 7 has both the absolute value of the direct current component Idc and the amplitude of the alternating current component Iac are equal to or greater than the reference values Ir1 and Ir2 defined in advance for each (that is, the contact current Itc is When the duration T1 of the contact current Itc exceeds m times the cardiac cycle Tc (m is a positive number), the fluctuation width Ipp of the contact current Itc is based on the waveform data D1. And the sine wave effective value Iev (= Ipp / (2 × √2)) of the contact current Itc is calculated, and the absolute value of the direct current component Idc and the amplitude of the alternating current component Iac are defined in advance for each reference. When the values are Ir1 and Ir2 or more and the duration T1 is less than n times the cardiac cycle Tc, the maximum absolute value Ip of the peak value of the contact current Itc is calculated based on the waveform data D1. Sinusoidal effective value of Rutotomoni contact current Itc for calculating the Iev (= Ip / √2). In this case, the above two calculation formulas for the sine wave effective value Iev are equations for calculating the effective value of the equivalent sine wave current defined in IEC60479-2. The reference value Ir1 is 0.005 mA, and the reference value Ir2 is 10% of the direct current component Idc.

  In the comparison process, the processing unit 7 compares the sine wave effective value Iev calculated in the effective value calculation process with a reference effective value Ievr defined in advance. In the output process, the processing unit 7 outputs the sine wave effective value Iev calculated in the effective value calculation process and the comparison result in the comparison process to the output unit 10. In this example, as will be described later, since the output unit 10 is configured by a display device (for example, a display device such as an LCD), the processing unit 7 executes display processing as an example of output processing and performs sine wave effective. The value Iev and the comparison result in the comparison process are displayed on the display device. Further, in the control process, the processing unit 7 outputs a control signal S1 and executes control for the switch circuit 4 (control of the relay connection / disconnection state).

  The storage unit 8 includes a ROM and a RAM, and stores reference values Ir1 and Ir2 and a reference effective value Ievr used in each process executed by the processing unit 7. The storage unit 8 stores calculation results and comparison results in each process, a cardiac cycle Tc input from the operation unit 9 and selection data D2 described later by the processing unit 7. The operation unit 9 includes a numeric keypad and a setting switch, and processes the cardiac cycle Tc and selection data D2 indicating one wiring connected to the human body simulation circuit 2 of the ground line G and the AC power supply lines AC1 and AC2. The unit 7 can be output. The output unit 10 is configured by a display device such as a display device as an example, and displays the calculation result and the comparison result of the processing unit 7.

  Next, the operation of the current measuring device 1 will be described. As shown in FIG. 1, the measurement target device 11 is supplied with the AC power supply Vac via the current measuring device 1 by connecting the power cord 13 to the output terminal portion 6 of the current measuring device 1. It shall be in the operating state. In addition, it is assumed that the current measuring device 1 is also in an operating state.

  In this state, the operator operates the operation unit 9 to input the cardiac cycle Tc and selection data D2 to the processing unit 7. The processing unit 7 causes the storage unit 8 to store the input cardiac cycle Tc and selection data D2. Further, the processing unit 7 controls the connection / disconnection state of each relay in the switch circuit 4 by outputting the control signal S1 to the switch circuit 4, and the single wiring (grounding) indicated by the selection data D2 is controlled. A line selected from the line G and the AC power supply lines AC1 and AC2 (in this example, the ground line G as an example) is connected to the terminal B of the human body simulation circuit 2.

  Thereafter, the operator brings the detection probe 2 a into contact with the exterior (exposed charging unit) of the measurement target device 11. Thereby, the contact current Itc flows between the measurement target device 11 and the ground wire G via the detection probe 2a and the human body simulation circuit 2, and the voltage Vtc indicating the contact current Itc is supplied from the terminal C of the human body simulation circuit 2. Is output. The A / D converter 3 samples the voltage Vtc to generate waveform data D1 for the contact current Itc (the current having the waveform shown in FIG. 3 or FIG. 4), and outputs the waveform data D1 to the processing unit 7.

  The processing unit 7 inputs this waveform data D1 and stores it in the storage unit 8. Next, the processing unit 7 performs a measurement process. In this measurement process, the processing unit 7 measures the absolute value of the direct current component Idc and the amplitude of the alternating current component Iac of the contact current Itc based on the waveform data D1. In this example, for example, regarding the contact current Itc having the waveform shown in FIGS. 3 and 4, the processing unit 7 assumes that the periodically changing waveform portion corresponds to the waveform of the AC component Iac, and the peak to Calculate the peak as the amplitude of the AC component Iac. Further, the absolute value of the center voltage in the amplitude of the AC component Iac is calculated as the absolute value of the DC component Idc. When there is no periodically changing portion in the waveform of the contact current Itc, the difference between the maximum value and the minimum value of the contact current Itc during the period in which the amplitude varies is calculated as the amplitude of the AC component Iac. For the absolute value of the DC component Idc, the absolute value of the average level of the contact current Itc during the period in which the amplitude of the AC component Iac is calculated is calculated as the absolute value of the DC component Idc. Finally, the processing unit 7 causes the storage unit 8 to store the absolute value of the DC component Idc and the amplitude of the AC component Iac of the measured (calculated) contact current Itc. Thereby, the measurement process is completed.

  Subsequently, the processing unit 7 executes an effective value calculation process. In this effective value calculation process, the processing unit 7 first calculates the absolute value of the DC component Idc for the contact current Itc stored in the storage unit 8 and the reference value for the DC component Idc stored in the storage unit 8. In addition to comparison with Ir1, the amplitude of the alternating current component Iac for the contact current Itc stored in the storage unit 8 is compared with the reference value Ir2 for the alternating current component Iac stored in the storage unit 8. As a result of this comparison, when the absolute value of the direct current component Idc is greater than or equal to the reference value Ir1 and the amplitude of the alternating current component Iac is greater than or equal to the reference value Ir2, the processing unit 7 determines that the contact current Itc is as shown in FIGS. It is determined that the direct current component is an alternating current, and the duration T1 (see FIGS. 3 and 4) of the contact current Itc is calculated based on the waveform data D1 stored in the storage unit 8. And stored in the storage unit 8. In this case, the duration of the contact current Itc refers to the time from when the contact current Itc is generated until it stops.

  Next, the processing unit 7 determines that the calculated duration T1 exceeds m times the cardiac cycle Tc stored in the storage unit 8 (m is a positive number, 1.5 as an example), or the cardiac cycle Tc. Is determined to be less than n times (n is a positive number less than m, for example, 0.75), or more than n times and less than m times the cardiac cycle Tc. When it is determined that it exceeds m times, the fluctuation width Ipp of the contact current Itc (difference between the minimum value and the maximum value within the duration T1; see FIGS. 3 and 4) is calculated based on the waveform data D1. The sine wave effective value Iev (= Ipp / (2 × √2)) of the contact current Itc is calculated and stored in the storage unit 8 as the sine wave effective value Iev1. Further, when the processing unit 7 determines that the duration T1 is less than n times the cardiac cycle Tc, the processing unit 7 calculates the maximum absolute value Ip of the peak value of the contact current Itc based on the waveform data D1 (see FIGS. 3 and 4). At the same time, the sine wave effective value Iev (= Ip / √2) of the contact current Itc is calculated and stored in the storage unit 8 as the sine wave effective value Iev2. Further, when the processing unit 7 determines that the duration T1 is not less than n times and not more than m times the cardiac cycle Tc, the above two types of sine wave effective values Iev1 and Iev2 (the sine wave is used unless otherwise distinguished). Wave effective value Iev) is calculated and stored in the storage unit 8. 3 and 4 show the waveform of the contact current Itc including the positive DC component Idc, the absolute value of the DC component Idc is also calculated for the waveform of the contact current Itc including the negative DC component Idc. Thus, the sine wave effective value Iev is calculated in the same manner as in the case of the waveform including the positive DC component Idc described above.

  On the other hand, as a result of the comparison between the absolute value of the DC component Idc and the reference value Ir1 and the comparison between the amplitude of the AC component Iac and the reference value Ir2, the absolute value of the DC component Idc is greater than or equal to the reference value Ir1. When the amplitude of the component Iac is less than the reference value Ir2, the processing unit 7 determines that the contact current Itc is a direct current, and makes contact according to a known measurement method (calculation method) defined by a standard such as IEC60990. The effective value (DC value) of the current Itc is measured and stored in the storage unit 8. Further, when the amplitude of the AC component Iac is equal to or greater than the reference value Ir2, but the absolute value of the DC component Idc is less than the reference value Ir1, the processing unit 7 determines that the contact current Itc is an AC current, IEC60990, etc. The effective value of the contact current Itc (the effective value of the alternating current) is measured and stored in the storage unit 8 in accordance with a known measurement method (calculation method) defined in the above standard. Thereby, the effective value calculation process is completed.

  Subsequently, the processing unit 7 executes a comparison process that compares the effective value calculated in the effective value calculation process with the reference effective value. In this comparison process, when the processing unit 7 calculates the sine wave effective value Iev in the effective value calculation process, the processing unit 7 compares the sine wave effective value Iev with the reference effective value Ievr stored in the storage unit 8 to determine the sine wave. When the wave effective value Iev exceeds the reference effective value Ievr, it is determined that the contact current Itc is at a level that affects the human body. When the sine wave effective value Iev is less than or equal to the reference effective value Ievr, the contact current Itc is applied to the human body. It is determined that the level is not influential, and the comparison result is stored in the storage unit 8. On the other hand, when the processing unit 7 measures the effective value of the contact current Itc in accordance with a known measurement method (calculation method) defined in a standard such as IEC60990, instead of the sine wave effective value Iev, in the effective value calculation process, The effect on the human body of the contact current Itc is determined by comparison with the reference effective value defined by the standard, and the comparison result is stored in the storage unit 8.

  Finally, the processing unit 7 calculates the sine wave effective value Iev calculated in the effective value calculation process or the comparison result of the comparison process (for example, since the sine wave effective value Iev is equal to or less than the reference effective value Ievr, the contact current Itc is The result indicating that the level is not affected is displayed on the display device of the output unit 10. Thus, the measurement of the effective value of the contact current Itc flowing from the measurement target device 11 to the ground wire G through the human body simulation circuit 2 is completed with the desired cardiac cycle Tc input from the operation unit 9 as a reference.

  Subsequently, when measuring the sine wave effective value Iev of the contact current Itc flowing from the measurement target device 11 to the wiring other than the ground wire G (AC power supply line AC1 or AC power supply line AC2), the operation unit 9 is operated, Selection data D2 indicating the AC power supply line AC1 or the AC power supply line AC2 is input to the processing unit 7. Thereby, the connection / disconnection state of each relay in the switch circuit 4 is controlled by the processing unit 7, and one wiring (wiring selected from the AC power supply lines AC1 and AC2) indicated by the selection data D2 is obtained. Connected to the terminal B of the human body simulation circuit 2, the measurement of the sine wave effective value Iev is performed by the processing unit 7 in this state. When the sine wave effective value Iev for the contact current Itc is measured by changing the cardiac cycle Tc, the operation unit 9 is operated to input the desired cardiac cycle Tc to the processing unit 7. Thereby, since the new cardiac cycle Tc is updated and stored in the storage unit 8 by the processing unit 7, the measurement of the sine wave effective value Iev of the contact current Itc in the desired cardiac cycle Tc is executed.

  Thus, according to the current measuring apparatus 1, the absolute value of the direct current component Idc and the amplitude of the alternating current component Iac are not less than the reference values Ir1 and Ir2 defined in advance for each (that is, the direct current is superimposed). When the duration T1 of the contact current Itc (which is an alternating current) exceeds m times the cardiac cycle Tc (1.5 times in the above example), the sine wave effective value Iev1 (= Ipp / (2 × √2)) Since the sine wave effective value Iev2 (= Ip / √2) can be calculated when the duration T1 is less than n times (0.75 times) the cardiac cycle Tc, DC The measurement and evaluation of the sine wave effective value Iev for the contact current Itc, which is an alternating current on which current is superimposed, can be performed in accordance with the IEC60479-2 standard. Further, based on the waveform data D1, the processing unit 7 determines whether or not the contact current Itc is an alternating current on which a direct current is superimposed, and what the duration T1 of the contact current Itc is based on the cardiac cycle Tc. Since the sine wave effective value Iev is automatically calculated by automatically determining whether it is in the length, the sine wave effective value Iev defined in IEC60479-2 can be calculated accurately and in a short time.

  Further, according to the current measuring apparatus 1, the processing unit 7 compares the calculated sine wave effective value Iev with a reference effective value Ievr specified in advance, and the comparison result (for example, the sine wave effective value Iev is the reference value). The sine wave effective value Iev for the contact current Itc, which is an alternating current on which a direct current is superimposed, is defined in the IEC60479-2 standard. As a result, it is possible to reliably recognize the result automatically performed.

  In addition, this invention is not limited to said structure. For example, each time the measurement of the sine wave effective value Iev of the contact current Itc with one wiring connected to the human body simulation circuit 2 is completed, the selection data D2 is input to the processing unit 7 by operating the operation unit 9 By doing this, the configuration (in the human body simulation circuit 2) that reselects one wiring (arbitrary one of the ground wire G, the AC power supply line AC1, and the AC power supply line AC2) to be connected to the human body simulation circuit 2 The configuration in which the wiring to be connected is manually changed is described above, but the measurement of the sine wave effective value Iev of the contact current Itc in a state where one wiring is connected to the human body simulation circuit 2 is completed. It is also possible to adopt a configuration in which the control for the switch circuit 4 is automatically executed each time, all the wirings are sequentially connected to the human body simulation circuit 2 and the sine wave effective value Iev of the contact current Itc is measured. According to this configuration, the manual wiring (the ground line G, the AC power supply line AC1, and the AC power supply line AC2) can be omitted, so that the time required for measurement can be further shortened. Further, it is possible to manually connect the human body simulation circuit 2 and the wiring (the ground wire G, the AC power supply line AC1, and the AC power supply line AC2). In this configuration, it takes time to manually switch the wiring. Since the switch circuit 4, the input terminal unit 5, and the output terminal unit 6 can be omitted, the configuration of the current measuring device 1 can be simplified.

  In addition, the current measuring apparatus 1 employs a configuration that measures the contact current Itc flowing between the exterior of one measurement target device 11 and one of the AC power supply lines AC1 and AC2 including the ground wire G. However, like the current measuring device 1A shown in FIG. 5, a configuration for measuring the contact current Itc flowing between the leakage current measuring terminals (F-type mounting portions) 11t and 11t of the two measuring target devices 11a and 11b is further measured. It can also be adopted. Hereinafter, the current measuring apparatus 1A will be described. The current measuring device 1A measures the contact current Itc flowing between the exterior of one measurement target device 11 and one of the AC power supply lines AC1 and AC2 including the ground wire G. Since the configuration is the same as that of the measuring apparatus 1, the same components are denoted by the same reference numerals and redundant description is omitted, and the leakage current measuring terminals 11t of the two measuring target devices 11a and 11b having different configurations are used. The structure for measuring the contact current Itc flowing between 11t and 11t will be mainly described.

  The current measuring device 1A is provided with two connectors 12a and 12b in its housing 1a. The detection probe 2a is connected to the connector 12a, and the detection probe 2b is connected to the connector 12b. The connector 12 a is connected to the terminal A of the human body simulation circuit 2. The switch circuit 4A has a four-contact circuit configuration that is one more contact than the switch circuit 4 of the current measuring device 1, and the increased one contact is connected to the connector 12b. The other three contacts are connected to the ground line G and the AC power supply lines AC1 and AC2 in the same manner as the switch circuit 4 (three-contact circuit configuration) of the current measuring device 1.

  With this configuration, in the current measurement device 1A, the detection probe 2a is connected to the leakage current measurement terminal 11t of one measurement target device 11a, and the detection probe 2b is connected to the leakage current measurement terminal 11t of the other measurement target device 11b. To do. In this state, in the control process, the processing unit 7 outputs a control signal S1 to control the switch circuit 4 (control of the relay connection / disconnection state), and connect the connector 12b to the terminal B of the human body simulation circuit 2. (The connection state in FIG. 5). Thereby, the contact current Itc flows between the two measurement target devices 11a and 11b via the leakage current measurement terminal 11t, the detection probe 2a, the human body simulation circuit 2, the detection probe 2b, and the leakage current measurement terminal 11t. A voltage Vtc indicating the current Itc is output from the terminal C of the human body simulation circuit 2. Therefore, according to the current measuring apparatus 1A, it is possible to measure the contact current Itc flowing between the two measurement target devices 11a and 11b, and calculate the sine wave effective value.

  In the current measuring devices 1 and 1A, the processing unit 7 compares the calculated sine wave effective value Iev with a comparison result (for example, a sine wave) between the sine wave effective value Iev and a predetermined reference effective value Ievr. When the effective value Iev is equal to or less than the reference effective value Ievr, the display device of the output unit 10 displays that the contact current Itc is not at a level that affects the human body. It is also possible to adopt a configuration for displaying the duration time T1, the fluctuation width Ipp, the maximum absolute value Ip of the peak value, and the like. The output unit 10 has been described above with respect to a configuration including a display device as an example, but it is needless to say that a configuration including a printing device such as a printer device, a communication device, and the like may be employed.

1 Current measuring device
2 Human body simulation circuit
3 A / D converter
7 Processing unit 10 Display unit 11 Device to be measured AC1, AC2 AC power supply line D1 Waveform data
G ground wire Iev sine wave effective value Itc contact current T1 duration Vtc voltage (voltage between both ends)

Claims (2)

The human body simulation circuit is connected to one of the AC power supply line including the ground wire and the exterior of the measurement target device, and between each leakage current measurement terminal of the two measurement target devices. A processing unit that measures an effective value of the contact current based on a voltage across both ends of a predetermined element constituting the human body simulation circuit due to the contact current flowing through the human body simulation circuit. Current measuring device,
An A / D conversion unit that samples the voltage between both ends and generates waveform data about the contact current, and an output unit,
The processing unit is configured to measure a direct current component and an alternating current component of the contact current based on the waveform data, and the absolute value of the direct current component and the magnitude of the alternating current component are both equal to or greater than a predetermined reference value. And when the duration of the contact current exceeds m times the cardiac cycle (m is a positive number), the fluctuation width Ipp of the contact current is calculated based on the waveform data and the fluctuation width Ipp is a value. The effective value of the sine wave of the contact current is calculated by dividing by (2 × √2), the magnitude of the direct current component and the magnitude of the alternating current component are both greater than or equal to the reference value, and the duration is When the cardiac cycle is less than n times (n is a positive number less than m), the maximum absolute value Ip of the peak value of the contact current is calculated based on the waveform data, and the maximum absolute value Ip is calculated as the value Ip / √. Divide by 2 Serial contact effective value calculating process for calculating the sine wave effective value of the current, and the current measuring apparatus of the sine wave effective value calculated in the effective value calculating process to execute the output process of outputting to the output unit. The output unit includes a display device,
The current measuring device according to claim 1, wherein the processing unit compares the sine wave effective value calculated in the effective value calculating process with a reference effective value defined in advance, and displays the comparison result on the display device. .

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