JP2017187355A - Measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce installation space of an input terminal occupying an entire surface.SOLUTION: A measurement device comprises: two input terminals 12a and 12b to which two output terminals of one of two output terminals 35a and 35b and two output terminals 54a and 54a about a current detection probe 2 detecting a detected current I to output a current detection signal from output terminals 35a and 35b of a connector 35, and about voltage detection probes 3 and 3 being used in a pair and outputting a voltage detection signal indicative of a detected voltage V from between the output terminals 54a and 54a of respective connectors 54 and 54 are capable of selectively connecting, in which the two input terminals are configured as a common input terminal,; and a measurement circuit unit 14 that, when the output terminals 35a and 35b are connected to the input terminals 12a and 12b, measures the detected current I on the basis of the current detection signal, and when the output terminals 54a and 54b are connected to the input terminals 12a and 12b, measures the detected voltage V on the basis of the voltage detection signal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a measuring apparatus including a plurality of input terminals capable of selectively connecting one output terminal of an output terminal of a current detection probe and an output terminal of a voltage detection probe.

  As an example of this type of measuring apparatus, a digital multimeter disclosed as a conventional technique in Patent Document 1 below is known. This digital multimeter freely arranges individual insertion of test leads determined based on the correspondence between the changeover switch that can be switched to each function such as voltage measurement and current measurement and the function that is determined by the changeover of this changeover switch. 3 input terminals (for example, a voltage measurement input terminal, a common input terminal that is a ground or a common, and a current measurement input terminal), and the selector switch and the three input terminals are arranged on the surface. It is configured.

  In another digital multimeter disclosed as a conventional technique in Patent Document 1, a circuit (internal circuit) necessary for voltage measurement is provided between the voltage measurement input terminal and the common input terminal. A circuit (other internal circuit) necessary for current measurement is provided between the current measurement input terminal and the common input terminal.

Japanese Patent Laid-Open No. 2002-350177 (2nd page, FIG. 5-6)

  However, the measurement apparatus described above has the following problems to be improved. That is, in this measuring apparatus, since the three input terminals of the voltage measuring input terminal, the common input terminal, and the current measuring input terminal are arranged on the surface, each measuring terminal is installed on the entire surface. There is a problem of large space.

  The present invention has been made in order to improve such a problem, and has as its main object to provide a measuring apparatus that can reduce the installation space of each input terminal occupying the entire surface.

  In order to achieve the above object, the measuring apparatus according to claim 1 includes: a current detection unit that detects a detected current and outputs a current detection signal; and two first output terminals for outputting the current detection signal to the outside. A current detection probe having a first connector portion arranged, and a second connector portion used for detecting a detected voltage and a second connector portion each having a voltage detection signal indicating the detected voltage. A plurality of input terminals that can selectively connect one of the two second output terminals of the voltage detection probe that outputs between two output terminals and one of the two first output terminals; When the one of the two output terminals connected to the input terminal is the two first output terminals, the detected current is measured based on the current detection signal output from the two first output terminals. In addition, when the one of the two output terminals connected to the plurality of input terminals is the two second output terminals, the detected voltage is based on the voltage detection signal output from the two second output terminals. The plurality of input terminals are configured as two common input terminals to which the one two output terminals can be connected.

  According to a second aspect of the present invention, there is provided the measuring apparatus according to the first aspect, comprising: a voltage source that outputs a DC voltage; and a switch that turns on and off the output of the DC voltage between the two shared input terminals. The current detection unit includes a coil unit that detects the current to be detected, and a detection circuit that detects a signal output from the coil unit and outputs the signal as the current detection signal. When one output terminal is connected to the two shared input terminals as the one two output terminals, the output of the DC voltage by the switch is turned on and the DC voltage is superimposed on the current detection signal. Thus, the DC voltage is supplied to the current detection probe as the operation voltage of the detection circuit.

  According to the measuring apparatus of claim 1, two input terminals are respectively connected to the two first output terminals disposed in the first connector portion of the current detection probe and the second connector portion of the pair of voltage detection probes. It is configured as a shared input terminal to which any one of the two second output terminals arranged can be connected.

  Therefore, according to this measuring apparatus, unlike the conventional configuration in which the three input terminals of the voltage measurement input terminal, the common input terminal, and the current measurement input terminal are arranged on the surface, the two input terminals are arranged on the surface. Therefore, the installation space for each input terminal on the entire surface can be sufficiently reduced.

  According to the measuring apparatus of the second aspect, the detection circuit which is likely to fail due to the application of overvoltage is disposed in the current detection probe, so that two current input terminals serving as two common input terminals are erroneously detected in the current measurement operation state. Even if the second output terminal of the pair of voltage detection probes is connected to the input terminal and a voltage is applied between the two input terminals, the occurrence of a situation in which the detection circuit fails due to the applied voltage is surely prevented. be able to.

It is an external view of measuring device 1 (1A), current detection probe 2, and voltage detection probes 3 and 3. It is a block diagram of the measuring apparatus 1 and the current detection probe 2 in FIG. It is a block diagram of other measuring apparatus 1A and other current detection probe 2A.

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

  First, the configuration of the measuring apparatus 1 as a measuring apparatus will be described with reference to the drawings.

  As shown in FIG. 1, the measuring device 1 is configured so that either one of the current detection probe 2 and the pair of voltage detection probes 3 and 3 can be selectively connected, and measurement is performed when the current detection probe 2 is connected. A current value I1 of a detected current (alternating current) I flowing in the target electric circuit 101 or the like is measured, and when the voltage detection probe 3 is connected, for example, a detected voltage (alternating voltage) V generated between both ends of the measuring object 111 is measured. It is possible to measure the voltage value V1.

  Specifically, as shown in FIGS. 1 and 2, the measurement apparatus 1 includes a case 11, two input terminals 12 a and 12 b, a selection switch 13, a measurement circuit unit 14, and an output unit 15. The case 11 is formed in a box (in this example, a rectangular parallelepiped box as an example) using an insulating synthetic resin material. The input terminals 12a and 12b are configured by terminals having the same configuration (for example, if one is a banana jack and the other is the same configuration), as an example in this example, the front surface 11a of the case 11 (selection switch 13 and The surface on which the output unit 15 is disposed). In this example, the input terminal 12b is connected to a portion (internal ground G) serving as a reference potential in the measurement circuit unit 14. In addition, about the input terminals 12a and 12b, the structure arrange | positioned in surfaces other than the front surface 11a in the case 11 (for example, any one of the side surfaces 11b, 11c, 11d, and 11e orthogonal to the front surface 11a). It may be.

  The selection switch 13 is a switch for selecting a measurement operation to be executed in the measurement apparatus 1 (that is, selecting either one of the current measurement operation and the voltage measurement operation). In this example, as an example, the front surface 11a of the case 11 is selected. It is arranged. The selection switch 13 can be constituted by a changeover switch such as a toggle switch, a rocker switch, a push button switch, a rotary switch, or a slide switch.

  As shown in FIG. 2, the measurement circuit unit 14 includes an input circuit 21, a processing circuit 22, and a voltage supply circuit 23. The input circuit 21 and the processing circuit 22 calculate a current value I1 based on a voltage signal (AC voltage signal) S1 input between the input terminals 12a and 12b when the current measurement operation is selected by the selection switch 13. On the other hand, when the voltage measuring operation is selected by the selection switch 13, the voltage value V1 is calculated.

  In this example, as an example, the input circuit 21 includes an input resistor 21a, a capacitor 21b, a ground resistor 21c, and a buffer amplifier 21d. The input resistor 21a is composed of a resistor having a high resistance value (for example, a resistance of several M ohms) for making the input impedance between the input terminals 12a and 12b high, and one end thereof is connected to the input terminal 12a. . Capacitor 21b has one end connected to the other end of input resistor 21a, and when a DC component (DC voltage Vdc described later) is superimposed on voltage signal S1, this DC component is removed, and AC component of voltage signal S1. Only from the other end. The grounding resistor 21c is connected between the other end of the capacitor 21b and the internal ground G. The grounding resistor 21c defines the center of the amplitude of the AC component of the voltage signal S1 output from the capacitor 21b as the potential of the internal ground G (zero volts). The buffer amplifier 21d receives the AC component of the voltage signal S1, and outputs the same amplitude to the processing circuit 22 with the same amplitude.

  The processing circuit 22 is configured by, for example, a DSP (Digital Signal Processor) including an A / D converter and the like, and inputs the AC component of the voltage signal S1 output from the input circuit 21 and switches the selection switch 13. A state (selection state) is detected, and when the detected switching state (selection state) is to select a current measurement operation, a current measurement operation is performed to calculate a current value I1 based on the AC component of the voltage signal S1. When the detected switching state (selected state) is to select the voltage measuring operation, the voltage measuring operation for calculating the voltage value V1 based on the AC component of the voltage signal S1 is executed. Further, when the processing circuit 22 calculates the current value I1 and the voltage value V1, the processing circuit 22 outputs the calculated current value I1 and voltage value V1 to the output unit 15.

  The voltage supply circuit 23 has a function of outputting (supplying) a DC voltage Vdc having a predetermined constant voltage value between the input terminals 12a and 12b. In this example, as an example, the voltage supply circuit 23 includes a thermistor (positive temperature coefficient thermistor) 23a, a switch 23b, a surge gap 23c, and a voltage source 23d. The thermistor 23a is an example of an overcurrent protection element, and one end is connected to the input terminal 12a. As an example, the switch 23b is configured by a switch (on / off switch) that switches in conjunction with the selection switch 13, and one end is connected to the other end of the thermistor 23a. Specifically, the switch 23b switches to an off state when the selection switch 13 is in a switching state (selection state) in which the voltage measurement operation is selected, and the switch 23b is in a switching state (selection state) in which the selection switch 13 selects a current measurement operation. Sometimes it turns on.

  The surge gap 23c is an example of an overvoltage protection element, and is connected between the other end of the switch 23b and the internal ground G. The voltage source 23d has one output terminal of a pair of output terminals (not shown) connected to the other end of the switch 23b and the other output terminal connected to the internal ground G. The voltage source 23d outputs a DC voltage Vdc (voltage based on the potential of the internal ground G) between the pair of output terminals. In this voltage supply circuit 23, the thermistor 23 a is an overcurrent protection circuit (voltage source 23 d) that limits the current value of the current toward the voltage source 23 d generated due to disturbance input between the input terminals 12 a and 12 b. The surge gap 23c is an overvoltage protection circuit (voltage source) that limits the voltage value of the voltage directed to the voltage source 23d generated due to disturbance input between the input terminals 12a and 12b. 23d protection circuit). The overcurrent protection circuit can be configured by using other known overcurrent protection elements other than the thermistor 23a described above (single use or combined use), and the overvoltage protection circuit is also described above. Other known overvoltage protection elements (for example, bidirectional Zener diodes) other than the surge gap 23c may be used (single use or combined use).

  For example, the output unit 15 includes a display device such as an LCD, and inputs the current value I1 and the voltage value V1 output from the processing circuit 22 of the measurement circuit unit 14 and displays them on the screen. The output unit 15 may be configured by various interface circuits instead of the display device. For example, the output unit 15 may store a current value I1 or a voltage value V1 in a removable medium as a media interface circuit, or a network as a network interface circuit. A configuration in which the current value I1 and the voltage value V1 are transmitted to the external device via the route can also be employed.

  Next, the configuration of the current detection probe 2 as a current detection probe will be described with reference to the drawings.

  As shown in FIG. 1, the current detection probe 2 is circularly bent around a measurement target circuit 101 such as a wire conductor or a bar conductor for supplying current, such as an electric wire or a bus bar, around the measurement target circuit 101. By mounting in an enclosed state, the current to be detected I (alternating current) flowing in the measurement target electric circuit 101 can be detected and a current detection signal Si can be output. In this example, the current detection probe 2 includes, as an example, a coil unit 31, a holding unit 32, a detection circuit unit 33, a signal cable 34 (for example, a two-core covered electric wire), and a connector 35 as a first connector unit. .

  As an example, the coil part 31 is provided with a flexible core material, a winding wound around the core material, and is disposed through the core material along the longitudinal direction of the core material. A flexible sensor (Rogowski coil in this example) is provided with a return line connected to one end portion of the wire and an insulating coating (both not shown) for covering the core material and the winding. With this configuration, the coil unit 31 generates a signal waveform detection signal Sd1 (see FIG. 2) obtained by differentiating the signal waveform of the detected current I flowing in the measurement target electric circuit 101, and the other end of the winding and the return line. Output from between the other end. The coil unit 31 constitutes a current detection unit CDT together with the detection circuit unit 33.

  The holding | maintenance part 32 is formed in the box shape as shown in FIG. 1 as an example using a synthetic resin material. Further, the other end portion (the right end portion in FIG. 1) of the coil portion 31 is fixedly connected to the holding portion 32 in a state of being inserted into the holding portion 32. The holding portion 32 is configured to be able to detachably hold one end portion of the coil portion 31 (left end portion in FIG. 1, the end portion on the one end portion side of the winding constituting the coil portion 31). .

  The detection circuit unit 33 is disposed in the holding unit 32 as shown in FIG. 1, and as shown in FIGS. 1 and 2, the other end of the winding constituting the coil unit 31 and the other end of the return line. Are connected to the signal cable 34 (both other end portions are indicated by the symbol A in the figure). In this case, as shown in FIGS. 1 and 2, the connector 35 connected to the signal cable 34 is provided with two first output terminals 35a and 35b (hereinafter also referred to as output terminals 35a and 35b). Yes. Each output terminal 35a, 35b is configured by a terminal having the same configuration (for example, if one is a banana plug, the other is the same configuration banana plug). As shown in FIGS. 1 and 2, the connector 35 is configured to be connectable to two input terminals 12a and 12b arranged in the measuring apparatus 1, but the output terminal 35a is connected to the input terminal 12a. And the output terminal 35b is connected to the input terminals 12a and 12b only in the polarity that is connected (inserted) to the input terminal 12b.

  The detection circuit unit 33 includes a decoupling circuit 41, an intermediate voltage generation circuit 42, and an integration circuit 43, as shown in FIG. In the detection circuit unit 33, as shown in FIG. 2, in the state where the current detection probe 2 is connected to the measuring device 1 via the connector 35, the internal ground G1 on the detection circuit unit 33 side is connected to the signal cable 34. The lead wire 34b, the output terminal 35b of the connector 35, and the input terminal 12b on the measuring device 1 side are connected to the internal ground G on the measurement circuit section 14 side in the measuring device 1, and the decoupling circuit 41 and the integrating circuit 43 are connected. The input circuit 21 and the voltage supply circuit 23 on the measurement circuit unit 14 side in the measurement apparatus 1 are connected to the other lead wire 34a in the signal cable 34, the output terminal 35a of the connector 35, and the input terminal 12a on the measurement apparatus 1 side. Connected.

  For example, the decoupling circuit 41 includes an impedance element 41a (which is a resistor in this example, but may be an inductor) having one end connected to the conducting wire 34a in the signal cable 34, and the other end of the impedance element 41a. A capacitor 41b connected between the internal ground G1 is provided. With this configuration, the decoupling circuit 41 is configured such that when the DC voltage Vdc is supplied from the voltage supply circuit 23 on the measurement device 1 side between the conducting wires 34a and 34b in the signal cable 34 via the input terminals 12a and 12b. The capacitor 41b is charged to the DC voltage Vdc via the impedance element 41a, and the charged DC voltage Vdc is output to the intermediate voltage generation circuit 42 and the integration circuit 43 in the detection circuit unit 33 as an operating voltage with low impedance.

  As an example, the intermediate voltage generation circuit 42 includes two voltage dividing resistors 42a and 42b, a capacitor 42c, and an operational amplifier 42d. The two voltage dividing resistors 42 a and 42 b are connected in parallel to the capacitor 41 b constituting the decoupling circuit 41 while being connected in series with each other. With this configuration, the two voltage dividing resistors 42a and 42b divide the DC voltage Vdc output from the decoupling circuit 41 at a ratio defined by the respective resistance values to generate an intermediate voltage Vme. In this example, the voltage dividing resistors 42a and 42b are defined to have the same resistance value as an example, so that the DC voltage Vdc is divided at a ratio of 0.5 to generate the intermediate voltage Vme (= Vdc / 2). This ratio is not limited to 0.5. For example, as long as it is within a range in which the integration circuit 43 can normally integrate the detection signal Sd1 as described later, an arbitrary value (for example, 0.4 or more and 0) .6 or less).

  The capacitor 42c is connected in parallel to the voltage dividing resistor 42b on the internal ground G1 side of the voltage dividing resistors 42a and 42b, and stabilizes the intermediate voltage Vme (reducing fluctuations in the intermediate voltage Vme). For example, the operational amplifier 42d is configured as a voltage follower circuit that operates with a DC voltage Vdc (that is, a positive voltage) with the internal ground G1 as a reference, and reduces the intermediate voltage Vme generated by the voltage dividing resistors 42a and 42b. The impedance is output to the integrating circuit 43.

  The integration circuit 43 is an example of a detection circuit, and includes an operational amplifier 43a, an input resistor 43b, a feedback capacitor 43c, and a capacitor 43d. For example, the operational amplifier 43a has a non-inverting input terminal connected to the other end of a winding constituting the coil unit 31, and the other end of a return line constituting the coil 31 is connected to the inverting input terminal of the input resistor 43b. Connected through. The non-inverting input terminal of the operational amplifier 43a is connected to the output terminal of the intermediate voltage generation circuit 42 (specifically, the output terminal of the operational amplifier 42d constituting the intermediate voltage generation circuit 42). The operational amplifier 43a has a feedback capacitor 43c connected between its output terminal and its inverting input terminal. One end of the capacitor 43 d is connected to the output terminal of the operational amplifier 43 a and the other end is connected to the conducting wire 34 a of the signal cable 34.

  In the integrating circuit 43, as shown in FIG. 2, the operational amplifier 43a operates with a DC voltage Vdc (that is, a positive voltage) with the internal ground G1 as a reference, but the potential of the non-inverting input terminal of the operational amplifier 43a is The detection signal Sd1 output from the coil unit 31 is an AC signal based on the intermediate voltage Vme, while being defined by the intermediate voltage Vme output from the intermediate voltage generation circuit 42. With this configuration, the integration circuit 43 flows in the measurement target electric circuit 101 by detecting (detecting normal integration) the detection signal Sd1 while operating with the DC voltage Vdc (that is, operating with a so-called single power supply). A current detection signal Si0 (an AC signal having the intermediate voltage Vme as a central potential) whose amplitude changes according to the signal waveform of the detected current I is generated and output to the capacitor 43d. The capacitor 43d removes the DC component (intermediate voltage Vme) included in the current detection signal Si0 and outputs it as a new current detection signal Si to the conducting wire 34a of the signal cable 34. This current detection signal Si is detected when the DC voltage Vdc is supplied from the voltage supply circuit 23 on the measuring device 1 side between the conducting wires 34a and 34b in the signal cable 34 via the input terminals 12a and 12b (that is, detected). When the intermediate voltage generation circuit 42 and the integration circuit 43 of the circuit unit 33 are operated), the measurement device 1 side is superimposed on the DC voltage Vdc (that is, as an AC signal having the DC voltage Vdc as the central potential). The signal is output via the signal cable 34.

  Then, the structure of the voltage detection probes 3 and 3 as a voltage detection probe is demonstrated with reference to drawings.

  As shown in FIG. 1, the two voltage detection probes 3 and 3 include a knob 51 formed in a column shape with an insulating synthetic resin material, a contact terminal 52 projecting from one end of the knob 51, A signal cable (for example, a one-core coated electric wire) 53 having one end side attached to the inside of the knob portion 51 from the other end of the knob portion 51 and one end side of the core wire connected to the contact terminal 52, and the signal cable 53 Each is provided with a connector 54 as a second connector portion disposed on the end side, and is configured identically. In this case, the connector 54 is provided with a second output terminal 54a (hereinafter also referred to as an output terminal 54a) to which the other end of the core of the signal cable 53 is connected. Further, the output terminal 54a is composed of terminals having the same configuration as the output terminals 35a and 35b. As shown in FIG. 1, any one of the two input terminals 12a and 12b disposed in the measuring apparatus 1 is used. It is configured to be connectable (pluggable) to one side. That is, the two input terminals 12a and 12b of the measuring apparatus 1 are connected to the output terminals 35a and 35b of the connector 35 on the current detection probe 2 side and the output terminals 54a and 54a of the connectors 54 and 54 on the voltage detection probe 3 and 3 side. Any one of the output terminals (specifically, any one set) can be connected as a common input terminal.

  Next, the measurement operation of the measurement apparatus 1 will be described.

  First, the current detection probe 2 is connected to the measurement apparatus 1 (the output terminals 35a and 35b are connected to the input terminals 12a and 12b), and the current value I1 of the detected current I flowing in the measurement target circuit 101 is measured. The measurement operation in this case will be described. As shown in FIG. 1, the current detection probe 2 is assumed to be attached to the measurement target electric circuit 101 so as to be bent in an annular shape and surround the measurement target electric circuit 101. It is assumed that the selection switch 13 is switched so as to select the current measurement operation.

  In this state, in the measuring apparatus 1, the voltage supply circuit 23 is switched to the ON state in conjunction with the switching state of the selection switch 13 (the switching state for selecting the current measurement operation). The DC voltage Vdc output from the source 23d is output (supplied) between the input terminals 12a and 12b. This DC voltage Vdc is supplied to the current detection probe 2 via the connector 35 and the signal cable 34.

  In the current detection probe 2, the coil unit 31 generates a signal waveform detection signal Sd 1 obtained by differentiating the signal waveform of the detected current I flowing in the measurement target electric circuit 101, and the other end of the winding and the other end of the return line. Output to the integration circuit 43 in the detection circuit unit 33. Further, the decoupling circuit 41 in the detection circuit unit 33 generates the DC voltage Vdc based on the internal ground G1 based on the DC voltage Vdc supplied from the measurement apparatus 1 in this way, and the detection circuit unit The output signal is output to the intermediate voltage generation circuit 42 and the integration circuit 43 in 33 at a low impedance. In the current detection probe 2, the DC voltage Vdc supplied from the measuring device 1 is also supplied to the integration circuit 43, but the DC voltage to the output terminal of the operational amplifier 43 a is provided by the capacitor 43 d provided in the integration circuit 43. Application of Vdc is avoided.

  In the current detection probe 2, the intermediate voltage generation circuit 42 generates an intermediate voltage Vme with the internal ground G1 as a reference based on the DC voltage Vdc, and outputs the intermediate voltage Vme to the integration circuit 43 with low impedance. In the integration circuit 43, the operational amplifier 43a that functions as an integrator by connecting the input resistor 43b and the feedback capacitor 43c detects (integrates) the detection signal Sd1, thereby detecting the detected current I flowing in the measurement target circuit 101. The current detection signal Si0 whose amplitude changes in accordance with the signal waveform is generated and output to the capacitor 43d. From this current detection signal Si0, the DC component (intermediate voltage Vme) included in the current detection signal Si0 is removed by the capacitor 43d, and a new current detection signal Si (AC component included in the current detection signal Si0) is obtained. Is output between the output terminals 35a and 35b of the connector 35 via the signal cable 34. In this case, since the DC voltage Vdc is supplied from the measuring device 1 side between the output terminals 35a and 35b, the current detection signal Si is superimposed between the output terminals 35a and 35b while being superimposed on the DC voltage Vdc. As a result, it is output between the input terminals 12a and 12b on the measuring apparatus 1 side.

  In the measuring apparatus 1, the input circuit 21 inputs the current detection signal Si with the DC voltage Vdc superimposed thereon as the voltage signal S1 through the input terminals 12a and 12b. In this case, in the input circuit 21, the input resistor 21a, the capacitor 21b, and the ground resistor 21c remove the DC component (DC voltage Vdc) included in the voltage signal S1, and are included in the voltage signal S1. The AC component (current detection signal Si) is an AC signal based on the potential of the internal ground G, and the AC component (current detection signal Si) is in a ratio defined by the resistance values of the input resistor 21a and the ground resistor 21c. Divide (reduce) the amplitude. The buffer amplifier 21d receives the divided current detection signal Si and outputs it to the processing circuit 22 with low impedance.

  The processing circuit 22 detects that the current switching state (selection state) of the selection switch 13 is to select the current measurement operation, and executes the current measurement operation. In this current measurement operation, the processing circuit 22 calculates a current value I1 based on the current detection signal Si output from the input circuit 21, and outputs the calculated current value I1 to the output unit 15. The output unit 15 inputs the current value I1 output from the processing circuit 22 and displays it on the screen. Thereby, the measurement of the current value I1 of the detected current I flowing in the measurement target electric circuit 101 by the measuring apparatus 1 is completed.

  Next, a pair of voltage detection probes 3 and 3 are connected to the measuring apparatus 1 (output terminals 54a and 54a are connected to the input terminals 12a and 12b), and the detected object generated between both ends of the measurement object 111 is detected. The measurement operation when measuring the voltage value V1 of the voltage V will be described. It is assumed that the voltage detection probes 3 and 3 are in contact with both ends of the measurement object 111 (both electrodes of the measurement object 111) as shown in FIG. Further, it is assumed that the selection switch 13 is switched so as to select the voltage measurement operation.

  In this state, in the measuring apparatus 1, the voltage supply circuit 23 switches the switch 23b to the off state in conjunction with the switching state of the selection switch 13 (the switching state for selecting the voltage measurement operation). The DC voltage Vdc output from the source 23d is not output (supplied) between the input terminals 12a and 12b. Thus, a voltage detection signal indicating the detected voltage V is input between the input terminals 12a and 12b of the measuring apparatus 1 via the voltage detection probes 3 and 3 as the voltage signal S1.

  In the measuring apparatus 1, the thermistor 23a having the positive temperature coefficient and the surge gap 23c are disposed in the voltage supply circuit 23 as described above. For this reason, in this measuring apparatus 1, the selection switch 13 is not switched to select the voltage measurement operation (that is, the selection switch 13 is switched to select the current measurement operation, and the switch 23b is Even when the detected voltage V is input through the voltage detection probes 3 and 3 in the ON state), the voltage supply circuit 23 is supplied from the input terminals 12a and 12b due to the input of the detected voltage V. When the current value of the current flowing in increases, the resistance value of the thermistor 23a increases, so that it is possible to avoid a situation where an overcurrent flows into the voltage supply circuit 23. Further, in this measuring apparatus 1, when the voltage value of the voltage input from the input terminals 12a and 12b to the voltage supply circuit 23 increases due to the input of the detected voltage V, the surge gap 23c operates. Thus, it is possible to avoid a situation in which an overvoltage is applied in the voltage supply circuit 23.

  In the measuring apparatus 1, the input circuit 21 inputs the detected voltage V as the voltage signal S1 through the input terminals 12a and 12b. In this case, in the input circuit 21, the input resistor 21a, the capacitor 21b, and the ground resistor 21c cause the AC component (the detected voltage V itself) included in the voltage signal S1 to be an AC signal based on the potential of the internal ground G. And the amplitude of the detected voltage V is divided (reduced) at a ratio defined by the resistance values of the input resistor 21a and the ground resistor 21c. Further, the buffer amplifier 21d receives the divided detected voltage V and outputs it to the processing circuit 22 with low impedance.

  The processing circuit 22 detects that the current switching state (selection state) of the selection switch 13 selects the voltage measurement operation, and executes the voltage measurement operation. In this voltage measurement operation, the processing circuit 22 calculates the voltage value V1 based on the detected voltage V output from the input circuit 21, and outputs the calculated voltage value V1 to the output unit 15. The output unit 15 inputs the voltage value V1 output from the processing circuit 22 and displays it on the screen. Thereby, the measurement of the voltage value V1 of the detected voltage V generated in the measurement object 111 by the measuring apparatus 1 is completed.

  Thus, in this measuring apparatus 1, the two input terminals 12a and 12b are connected to the output terminals 35a and 35b of the connector 35 on the current detection probe 2 side and the output terminals 54a of the connector 54 on the voltage detection probe 3 and 3 side. Any one of the output terminals can be connected as a shared input terminal.

  Therefore, according to this measuring apparatus 1, unlike the conventional configuration in which the three input terminals of the voltage measurement input terminal, the common input terminal, and the current measurement input terminal are arranged on the surface, the two on the surface of the case 11 Since only the input terminals 12a and 12b need to be arranged, the installation space for the input terminals 12a and 12b on the entire surface of the case 11 can be sufficiently reduced.

  Further, in the measuring apparatus 1, a voltage source 23d that outputs a DC voltage Vdc and a switch 23b that turns on and off the output of the DC voltage Vdc between two input terminals 12a and 12b as two common input terminals are provided. And a coil part 31 as a Rogowski coil for detecting the detected current I and an integration circuit 43 for integrating the detection signal Sd1 output from the coil part 31 and outputting it as a current detection signal Si. When the two output terminals 35a and 35b of the current detection probe 2 having the current detection unit CDT are connected to the input terminals 12a and 12b as the common input terminals, the output of the DC voltage Vdc by the switch 23b is turned on. By superimposing the DC voltage Vdc on the current detection signal Si, the DC voltage Vdc is used as the operating voltage of the integrating circuit 43 to detect the current. Supplied to the probe 2.

  Therefore, according to this measuring apparatus 1, the integration circuit 43 that is likely to fail due to the application of an overvoltage is disposed in the current detection probe 2, so that in the state of the current measurement operation, 2 as two shared input terminals can be mistakenly detected. Even when the voltage detection probes 3 and 3 are connected to the two input terminals 12a and 12b and a voltage is applied between the input terminals 12a and 12b, the integration circuit 43 is surely generated by the applied voltage. Can be prevented.

  In addition, although said coil part 31 is provided with the flexible core material (usually the core material formed with the nonmagnetic material) and is comprised as a Rogowski coil, the coil part 31 is this structure. For example, the magnetic core (not shown) and a detection coil (not shown) wound around the magnetic core may be used. In this configuration, the detection coil outputs a detection signal Sd1 having an amplitude proportional to the current value I1 (amplitude) of the detected current (alternating current) I from both ends thereof. For this reason, the detection circuit unit constituting the current detection unit CDT is illustrated instead of the configuration of the detection circuit unit 33 including the decoupling circuit 41, the intermediate voltage generation circuit 42, and the integration circuit 43 (configuration illustrated in FIG. 2). However, it is the same as the integration circuit 43 except that the decoupling circuit equivalent to the decoupling circuit 41, the intermediate voltage generation circuit equivalent to the intermediate voltage generation circuit 42, and, for example, the feedback capacitor 43c in the integration circuit 43 is replaced with a feedback resistor. The detection signal Sd1 is detected and output to the connector unit 35 as a current detection signal Si. In addition, about the structure same as the electric current detection probe 2, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted. Also in this configuration, an amplifier circuit that is likely to fail due to the application of an overvoltage is provided in the current detection probe 2, so that, in the same manner as the configuration of the integration circuit described above, the two are erroneously shared in the current measurement operation state. Even if the voltage detection probes 3 and 3 are connected to the two input terminals 12a and 12b as the input terminals and a voltage is applied between the input terminals 12a and 12b, the amplifier circuit is broken by the applied voltage. Occurrence can be reliably prevented.

  Further, while the integration circuit 43 is disposed in the current detection probe 2 as described above, a DC voltage Vdc as an operation voltage of the integration circuit 43 is output between the input terminals 12a and 12b to which the current detection signal Si is input. Then, by adopting a configuration in which the current detection signal Si is superimposed and supplied to the current detection probe 2 side, the number of input terminals 12a and 12b provided in the measurement apparatus 1 is reduced to two while the integration circuit 43 The example of avoiding the failure has been described above, but the configuration for avoiding the failure of the integration circuit 43 while reducing the number of input terminals 12a and 12b arranged in the measurement apparatus to two is not limited to this.

  For example, a measuring apparatus 1A configured as shown in FIG. 3 may be used. Hereinafter, the measurement apparatus 1A, and the current detection probe 2A and the voltage detection probes 3 and 3 connected to the measurement apparatus 1A will be described. In addition, about the structure same as the structure of the measuring apparatus 1, the current detection probe 2, and the voltage detection probes 3 and 3 which are shown in FIG. 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  As shown in FIGS. 1 and 3, the measurement apparatus 1 </ b> A includes a case 11, two input terminals 12 a and 12 b, a selection switch 13, a measurement circuit unit 14, and an output unit 15.

  As shown in FIG. 3, the measurement circuit unit 14 includes an input circuit 21, a processing circuit 22, three switches 24, 25, 26, a protection circuit 27, and an integration circuit 43. In this measuring apparatus 1A, a switch 24 is disposed between the input terminal 12a and the input circuit 21. The switch 24 has one end connected to the input terminal 12 a and the other end connected to the input circuit 21. The switch 25 has one end connected to one end of the switch 24 and the other end connected to the protection circuit 27. The protection circuit 27 is disposed between the other end of the switch 25 and the input resistor 43 b of the integration circuit 43. The switch 26 has one end connected to the capacitor 43d constituting the integrating circuit 43 and the other end connected to the input side of the input circuit 21 (one end of the input resistor 21a).

  Each of the switches 24, 25, and 26 includes, for example, a switch (on / off switch) that switches in conjunction with the selection switch 13, and when the selection switch 13 is in a switching state (selection state) in which a voltage measurement operation is selected. The switch 24 is turned on and the switches 25 and 26 are turned off. On the other hand, when the selection switch 13 is in the switching state (selected state) for selecting the current measurement operation, the switch 24 is turned off. At the same time, the switches 25 and 26 are turned on.

  The protection circuit 27 has a function of preventing an overcurrent or an overvoltage from being applied from the input terminal 12a to the integration circuit 43 when the switches 25 and 26 are in an on state. Further, since the protection circuit 27 is connected in series with the input resistor 43b of the integrating circuit 43, the resistance value thereof is defined to be sufficiently small with respect to the resistance value of the input resistor 43b. Further, in the integration circuit 43 of this example, the operational amplifier 43a includes a positive voltage + Vcc and a negative voltage −Vcc (an internal ground on the measurement circuit unit 14 side) generated by a power supply unit (not shown) provided in the measurement apparatus 1A. A voltage generated with reference to G) is used as an operating voltage.

  In this measurement apparatus 1A, when the output terminals 35a and 35b of the connector 35 in the current detection probe 2A are connected to the input terminals 12a and 12b and the current value I1 of the detected current I flowing in the measurement target circuit 101 is measured, By setting the selection switch 13 to a switching state (selection state) for selecting the current measurement operation, the switch 24 is turned off and the switches 25 and 26 are turned on. As a result, since a series circuit of the protection circuit 27 and the integration circuit 43 is interposed between the input terminals 12a and 12b and the input circuit 21, the voltage signal input between the current detection probe 2A and the input terminals 12a and 12b. (AC voltage signal) Based on S1, the processing circuit 22 can calculate the current value I1 of the detected current I and output it to the output unit 15.

  Further, in this measuring apparatus 1A, the output terminals 54a and 54a of the connectors 54 of the voltage detection probes 3 and 3 are connected to the input terminals 12a and 12b, and the detected voltage V generated between both ends of the measurement object 111. When the voltage value V1 is measured, the switch 24 is turned on and the switches 25 and 26 are turned off by setting the selection switch 13 to a switching state (selection state) for selecting the voltage measurement operation. . Thus, the series circuit of the protection circuit 27 and the integration circuit 43 is disconnected from the input terminals 12a and 12b, and the input circuit 21 is connected to the input terminal 12a via the switch 24. For this reason, the detected voltage V is input as the voltage signal S1 to the input circuit 21 via the voltage detection probes 3 and 3 and the input terminals 12a and 12b, so that the processing circuit 22 is detected based on the voltage signal S1. The voltage value V <b> 1 of the voltage V can be calculated and output to the output unit 15.

  Therefore, also in this measuring apparatus 1A, unlike the conventional configuration in which three input terminals of the voltage measurement input terminal, the common input terminal, and the current measurement input terminal are arranged on the surface, two inputs are provided on the surface of the case 11. Since only the terminals 12a and 12b need to be arranged, the installation space for the input terminals 12a and 12b on the entire surface of the case 11 can be sufficiently reduced. Even if the integrating circuit 43 is provided in the measuring apparatus 1A, the protection circuit 27 is provided between the integrating circuit 43 and the input terminal 12a. Even if the voltage detection probes 3 and 3 are connected to the two input terminals 12a and 12b serving as the two common input terminals and a voltage is applied between the input terminals 12a and 12b, the integration circuit 43 is applied by the applied voltage. The occurrence of a situation such as failure can be reliably prevented.

DESCRIPTION OF SYMBOLS 1,1A Measuring apparatus 2,2A Current detection probe 3 Voltage detection probe 12a, 12b Input terminal 13 Selection switch 14 Measurement circuit part 23b Switch 23d Voltage source 35 Connector 35a, 35b Output terminal 43 Integration circuit 54 Connector 54a Output terminal Si current Detection signal

Claims (2)

A current detection probe having a current detection unit for detecting a detected current and outputting a current detection signal; a first connector unit having two first output terminals for outputting the current detection signal to the outside; and The two second detection terminals of the voltage detection probe that are used as a pair to detect the detected voltage and output a voltage detection signal indicating the detected voltage from between the second output terminals of the second connector portions respectively disposed. A plurality of input terminals to which two output terminals of one of the two output terminals and the two first output terminals can be selectively connected;
When the one of the two output terminals connected to the plurality of input terminals is the two first output terminals, the current to be detected is measured based on the current detection signals output from the two first output terminals. In addition, when the one of the two output terminals connected to the plurality of input terminals is the two second output terminals, the detection target is based on the voltage detection signals output from the two second output terminals. A measuring device including a measuring circuit unit for measuring voltage,
The plurality of input terminals are configured as two common input terminals to which the one two output terminals can be connected. A voltage source that outputs a DC voltage;
A switch for turning on and off the output of the DC voltage between the two shared input terminals,
The current detection unit includes a coil unit that detects the detected current and a detection circuit that detects a signal output from the coil unit and outputs the signal as the current detection signal.
When the two first output terminals are connected to the two shared input terminals as the one two output terminals, the output of the DC voltage by the switch is turned on and the DC voltage is converted into the current detection signal. The measuring apparatus according to claim 1, wherein the DC voltage is supplied to the current detection probe as an operating voltage for the detection circuit by superimposing the DC voltage on the current detection probe.

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