JP2009041925A - Clamp type sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clamp type sensor capable of simplifying measurement operation. <P>SOLUTION: The clamp type sensor comprises: a clamp part 5 having a stationary sensor arm 13 and a movable sensor arm 15 being configured to clamp an electric wire 4 to be measured so as to detect current I1 flowing in the electric wire 4 to be measured in a clamped state (closed state); and a detection electrode 12 arranged in the clamp part 5 so as to measure voltage V1 of the electric wire 4 to be measured, wherein the detection electrode 12 is disposed in the stationary sensor arm 13 of the clamp part 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a clamp type sensor capable of detecting a current flowing through a measurement target electric wire and a voltage of the measurement target electric wire.

The applicant of the present application has proposed an apparatus for measuring current and voltage flowing in a measurement target electric wire in Japanese Patent Application Laid-Open No. 2006-343109. This device includes a voltage measuring probe (clamp-type voltage sensor) that clamps a measurement target electric wire and detects the voltage in a non-contact manner via capacitive coupling and outputs an induced voltage, and is formed in a substantially circular shape and has a tip that is A current-corresponding signal whose amplitude is proportional to the current value of the current flowing through the measurement target wire clamped by this clamp part, which is configured to be openable and closable and has a magnetic core (iron core) disposed inside. And a current measuring probe (clamp-type current sensor) configured to measure the power supplied from the measurement target electric wire based on the induced voltage and the current corresponding signal.
JP 2006-343109 A (page 4-5, FIG. 1)

  However, the above power measuring apparatus has the following problems to be solved. That is, in this power measuring device, since the voltage measuring probe and the current measuring probe are separated from each other, it is necessary to clamp the voltage measuring probe and the current measuring probe on the measurement target electric wires at the time of measurement, and the measurement work is complicated. There is a problem to be solved.

  The present invention has been made to solve the above-described problems, and has as its main object to provide a clamp-type sensor that can simplify the measurement work.

  In order to achieve the above object, the clamp type sensor according to claim 1 is configured to be capable of clamping the measurement target electric wire, and is provided in the clamp unit for detecting the current flowing in the measurement target electric wire, and the clamp unit. And a detection electrode for detecting the voltage of the measurement target electric wire.

  The clamp type sensor according to claim 2 is the clamp type sensor according to claim 1, wherein the clamp part includes a magnetic path forming part surrounding the measurement target electric wire, and passes through the magnetic path forming part. A current detector that detects the current based on a change in magnetic flux to be generated.

  According to a third aspect of the present invention, there is provided the clamp type sensor according to the second aspect, further comprising: a sensor main body portion in which the current detection portion is disposed, and one end portion of the clamp portion is the sensor main body. A fixed sensor arm that is fixed to the sensor and has the detection electrode disposed therein, and one end of which is rotatably attached to the sensor main body and the other end of which is fixed to the other end of the fixed sensor arm. A movable sensor arm configured to be able to contact and separate, and one end portion of the movable sensor arm, together with the one end portion of the movable sensor arm, rotatably attached to the sensor main body portion, between the fixed sensor arm and the movable sensor arm. An arrangement position of the detection electrode in the fixed sensor arm at the other end of the electric wire to be measured clamped by the fixed sensor arm and the movable sensor arm And a presser arm to press the vicinity.

  According to a fourth aspect of the present invention, there is provided the clamp type sensor according to the second aspect, further comprising: a sensor main body portion in which the current detection portion is disposed, and one end portion of the clamp portion is the sensor main body. A fixed sensor arm fixed to a portion, the detection electrode is disposed inside, one end portion is rotatably attached to the sensor main body portion, and the other end portion is opposite to the other end portion of the fixed sensor arm. A movable sensor arm configured to be able to contact and separate, and one end portion of the movable sensor arm, together with the one end portion of the movable sensor arm, rotatably attached to the sensor main body portion, between the fixed sensor arm and the movable sensor arm. An arrangement position of the detection electrode in the movable sensor arm at the other end of the electric wire to be measured clamped by the fixed sensor arm and the movable sensor arm And a presser arm to press the vicinity.

  The clamp type sensor according to claim 5 is the clamp type sensor according to claim 2, further comprising a sensor main body portion in which the current detection portion is disposed, and one end portion of the clamp portion is the sensor main body. A fixed sensor arm fixed to the sensor, and a movable sensor arm having one end rotatably attached to the sensor main body and the other end detachable from the other end of the fixed sensor arm. And one end of the detection electrode is rotatably attached to the sensor main body together with the one end of the movable sensor arm, and between the fixed sensor arm and the movable sensor arm. The measurement target electric wire that is disposed and clamped by the fixed sensor arm and the movable sensor arm is connected to the other end of the fixed sensor arm and the movable sensor arm. And a presser arm to press Re or one.

  In the clamp type sensor according to claim 1, a detection electrode for measuring the voltage of the measurement target wire is arranged in a clamp portion configured to clamp the measurement target wire and detecting a current flowing through the measurement target wire. It is installed. Therefore, according to this clamp type sensor, unlike the configuration in which the voltage measurement probe and the current measurement probe are separated, the current and voltage flowing through the measurement target electric wire and the power are measured by one clamping operation. Therefore, the measurement work can be greatly simplified.

  In the clamp type sensor according to claim 2, the clamp unit is configured to include a magnetic path forming unit that surrounds the measurement target electric wire, and a current detection unit that detects current based on a change in magnetic flux passing through the magnetic path forming unit is provided. I have. Therefore, according to this clamp type sensor, the magnetic path forming part of the clamp part can guide the magnetic flux to the current detection part with little leakage, so that the current detection part detects the current with high accuracy based on the change of the magnetic flux. be able to.

  Further, in the clamp type sensor according to the third, fourth, and fifth aspects, the one end portion is rotatably attached to the sensor main body portion together with the one end portion of the movable sensor arm, and between the fixed sensor arm and the movable sensor arm. A pressing arm is disposed on the side. Therefore, according to this clamp type sensor, the measurement target electric wire clamped by the fixed sensor arm and the movable sensor arm can be pressed against one of the fixed sensor arm and the movable sensor arm at the other end of the pressing arm. . For this reason, by arranging the detection electrode in a portion where the measurement target electric wire of one of the fixed sensor arm, the movable sensor arm, and the holding arm is pressed, the measurement target electric wire is placed near the position where the detection electrode is arranged. Can be pressed down reliably. For this reason, it is important when measuring the voltage of a measurement target wire in a non-contact manner compared to a configuration in which the measurement target wire is clamped in a state where the measurement target wire can freely move between a fixed sensor arm and a movable sensor arm. As a result, it is possible to reduce the fluctuation of the capacitance value of the capacitance formed between the measurement target wire and the detection electrode. Can also be measured with high accuracy. In the present specification, “measurement without contact” means that measurement is performed in a state where the detection electrode is in contact with the insulation coating of the measurement target electric wire but is not in contact with the conductor.

  Hereinafter, the best mode of a clamp type sensor according to the present invention will be described with reference to the accompanying drawings by taking an example applied to a power measuring apparatus as an example.

  First, the power measuring device 1 will be described with reference to the drawings.

  As shown in FIG. 1, the power measuring device 1 includes a clamp type sensor 2 and a main unit 3 according to the present invention, and measures the current I1 flowing through the measurement target wire 4 and the voltage V1 of the measurement target wire 4 as well as measurement. The electric power W1 sent through the measurement target electric wire 4 based on the current I1 and the voltage V1 that can be measured without contact.

  As shown in FIG. 1, the clamp type sensor 2 includes a clamp part 5 and a sensor main body part 6. In this case, the clamp unit 5 is configured to be able to clamp the measurement target electric wire 4 and has a function of measuring the current I1 flowing through the measurement target electric wire 4. The clamp unit 5 includes magnetic cores 11a and 11b for measuring the current I1 flowing through the measurement target wire 4 in a non-contact manner, and a flat detection electrode for measuring the voltage V1 of the measurement target wire 4 in a non-contact manner. 12 are arranged inside. Each of the magnetic cores 11a and 11b is a magnetic path forming portion in the present invention. As shown in the figure, when the clamp portion 5 clamps the measurement target wire 4, the measurement target wire 4 is surrounded and closed magnetically. A path is formed, and the magnetic flux generated around the measurement target wire 4 due to the current I1 flowing through the measurement target wire 4 is efficiently guided to the detection coil 14 described later.

  Specifically, the clamp portion 5 has one end portion (the right end portion in the figure) fixed to the sensor body portion 6 and a fixed sensor arm 13 in which the magnetic core 11a and the detection electrode 12 are disposed. The magnetic core 11b and the detection coil 14 wound around the magnetic core 11b are disposed inside, and one end (the right end in the figure) is rotatably attached to the sensor body 6 and the other end. The movable sensor arm 15 is configured such that the portion (left end portion in the figure) can be brought into contact with and separated from the other end portion (left end portion in the figure) of the fixed sensor arm 13, and one end portion of the movable sensor arm 15. A pressing arm 16 is provided between the fixed sensor arm 13 and the movable sensor arm 15 and is rotatably attached to the sensor body 6 together with one end. In this case, the detection coil 14 constitutes a current detection unit in the present invention together with a current detection circuit 32 described later. The fixed sensor arm 13, the movable sensor arm 15 and the pressing arm 16 are made of a synthetic resin material having electrical insulation. The holding arm 16 has a shorter overall length than the fixed sensor arm 13 and the movable sensor arm 15, and rotates in the inner region of the fixed sensor arm 13 and the movable sensor arm 15. The measurement target electric wire 4 clamped by the sensor arm 15 has a function of pressing the detection electrode 12 in the vicinity of the arrangement position of the detection electrode 12 in the fixed sensor arm 13 at the other end.

  In more detail, the structure of the sensor main body 6, the movable sensor arm 15, and the pressing arm 16 will be described with reference to FIGS. A first operation lever 17 extending in the opposite direction to the movable sensor arm 15 is attached to one end of the movable sensor arm 15 so that both are integrally formed. Further, a second operation lever 18 extending in the opposite direction to the pressing arm 16 is attached to one end portion of the pressing arm 16 so that both are integrally formed. In this case, the first operating lever 17 and the second operating lever 18 close the opening 6a to the opening 6a provided on one side wall (the upper side wall in FIGS. 6 and 7) of the sensor body 6. It is arranged in this way. The second operation lever 18 is disposed in a state of covering the first operation lever 17.

  Further, as shown in FIG. 6, the first operation lever 17 is always in a direction protruding from the opening 6 a of the sensor main body 6 by a spring (torsion coil spring as an example) 19 provided in the sensor main body 6. It is energized. As a result, the movable sensor arm 15 to which the first operation lever 17 is attached is always urged by the spring 19 so as to rotate in the direction of the fixed sensor arm 13. On the other hand, as shown in FIG. 6, the second operating lever 18 is always operated by a spring (for example, a coil spring) 20 disposed between the first operating lever 17 and the second operating lever 18. It is biased in a direction away from the lever 17 (a direction protruding from the opening 6a). As a result, the pressing arm 16 to which the second operation lever 18 is attached is always urged by the spring 20 so as to rotate in the direction of the fixed sensor arm 13.

  As shown in FIG. 1, the sensor body 6 includes a case 31, a current detection circuit 32, a variable capacitance circuit 33, a current detector 34, and a preamplifier 35. The case 31 is configured using a conductive material (for example, a metal material). Further, the surface of the case 31 is covered with the insulating film RE1, and the variable capacitance circuit 33, the current detector 34, and the preamplifier 35 are disposed therein. As shown in the figure, the current detection circuit 32 surrounds the measurement target wire 4 by the magnetic cores 11a and 11b when the clamp unit 5 clamps the measurement target wire 4 (when the clamp unit 5 is in the closed state). The change in the magnetic flux in the closed magnetic circuit formed in this way, that is, the change in the magnetic flux passing through the detection coil 14 is detected, and the amplitude changes according to the current value of the current I1 flowing through the measurement target wire 4 (as an example) The current detection signal S9 is output in which the amplitude changes in proportion to the current value.

  As shown in FIGS. 1 and 2, the variable capacitance circuit 33 includes one capacitance change function body 41 and one drive circuit 42. The capacity changing function body 41 includes a first structural unit 51, a second structural unit 52, a third structural unit 53, and a fourth structural unit 54 connected in this order in a ring shape (bridge shape). It is configured as a bridge circuit. Specifically, as shown in FIG. 3, each of the structural units 51, 52, 53, 54 includes first electric elements E11, E12, E13, E14 (hereinafter referred to as “first electric element E1 unless otherwise specified). Are also included one by one.

  In this case, each first electrical element E1 functions as a resistor when one end has a high potential with respect to the other end, and functions as a capacitor when the other end has a high potential with respect to the other end. Each of the first elements 61a and 61b (hereinafter also referred to as the first element 61 unless otherwise distinguished), and the first elements 61 are connected in series in opposite directions. Thereby, each 1st electric element E1 is comprised so that a capacity | capacitance may change according to the magnitude | size of the absolute value of an applied voltage, preventing passage of a DC signal. In this example, as an example, each first element 61 includes a P-type semiconductor and an N-type semiconductor that are joined to each other, and specifically includes one diode (for example, a variable-capacitance diode; a varicap or a varactor. Each first electric element E1 is configured by connecting these two diodes in series in opposite directions (with anode terminals connected to each other). In addition, variable capacitance diodes having the same or substantially the same characteristics are used for the first elements 61a and 61b, and the product of the impedances of the first structural unit 51 and the third structural unit 53 and the second configuration. The product of each impedance of the unit 52 and the fourth structural unit 54 is set to be the same or substantially the same (for example, a state that is different within a range of about several percent).

  In the capacity change function body 41 shown in FIG. 3, each first electrical element E1 connects one ends of a pair of first elements 61a and 61b (connects anode terminals of a pair of diodes). Although it is configured, each first electrical element E1 can be configured by connecting the other ends of the pair of first elements 61a and 61b (connecting the cathode terminals of the pair of diodes). The variable capacitance diode uses a change in capacitance (junction capacitance) due to a change in the thickness of the depletion layer at the PN junction of the diode when a voltage is applied in the reverse direction. This is the one with a large change. On the other hand, even in a general diode (silicon diode) configured with a PN junction, the above-described change in capacitance (junction capacitance) occurs although it is less than a variable capacitance diode. For this reason, all the 1st elements 61a and 61b in the capacity | capacitance change function body 41 shown in FIG. 3 can also be replaced by a general diode. In addition, for the second structural unit 52 and the third structural unit 53 in the capacity change function body 41, the first electrical elements E12 and E13 are replaced by the second electrical elements E22 and E23 that allow passage of an AC signal. It can also be replaced. In this case, the second electrical elements E22 and E23 are configured to include at least one of a coil, a resistor, and a capacitor. As an example, in FIG. 3, the second electrical elements E22 and E23 include one coil 62a and 63a (having the same inductance value), one resistor 62b and 63b (having the same resistance value), or one capacitor 62c and 63c. An example in which the capacitance values are the same is shown.

  In addition, as shown in FIGS. 1 and 2, the variable capacitance circuit 33 is a first structural unit in the capacitance change function body 41 between the detection electrode 12 and the portion (the case 31 in this example) that becomes the reference potential Vr. 51 and the fourth structural unit 54 are arranged so that the connection point A is located on the detection electrode 12 side, and the connection point C of the second structural unit 52 and the third structural unit 53 is located on the case 31 side. ing. Specifically, as shown in FIGS. 1 and 2, the variable capacitance circuit 33 has a connection point A of the capacitance change function body 41 connected to the detection electrode 12 and a connection point C of the capacitance change function body 41 connected to the current. It is connected to the case 31 via the detector 34. A connection point B between the first structural unit 51 and the second structural unit 52 and a connection point D between the third structural unit 53 and the fourth structural unit 54 are connected to the drive circuit 42.

  The drive circuit 42 is configured using, for example, insulating electronic components such as a transformer and a photocoupler, and the drive signal S1 input from the main unit 3 is electrically insulated from the drive signal S1 and the drive signal S1. To the drive signal S2 having the same frequency f1 and output (applied) to the capacitance changing function body 41. In this example, as an example, the drive circuit 42 is configured by using an insulating transformer 42a having a primary winding 42b and a secondary winding 42c, as shown in FIG. In this case, each end of the secondary winding 42 c is connected to the connection points B and D of the capacitance change function body 41. In the drive circuit 42, the primary winding 42b is excited based on the input drive signal S1, so that the transformer 42a generates the drive signal S2 in the secondary winding 42c. With this configuration, the drive circuit 42 converts the drive signal S1 into the drive signal S2 with low distortion, and applies the drive signal S2 between the connection points B and D of the capacitance change function body 41. In this example, since a sine wave signal is used as the drive signal S1 as an example as described later, the drive signal S2 is also output as a sine wave signal. In addition, instead of the drive circuit 42 described above, a floating signal source (not shown) that outputs the drive signal S2 alone (without inputting the drive signal S1 from the main unit 3) is provided in the clamp type sensor 2. It can also be arranged.

  The current detector 34 includes a resistor as an example, and is connected between the variable capacitance circuit 33 (specifically, the capacitance changing function body 41 of the variable capacitance circuit 33) and the case 31. As a result, the current detector 34 is disposed between the detection electrode 12 and the case 31 in a state of being connected in series with the variable capacitance circuit 33 and flows to the capacitance changing function body 41 of the variable capacitance circuit 33. A current i (physical quantity) is detected, and a voltage V2 having a value proportional to the current value of the current i and having a polarity corresponding to the direction of the current i is generated between both ends thereof. Of course, an insulating transformer may be used as the current detector 34. The preamplifier 35 includes a pair of DC blocking capacitors (not shown), an amplifier circuit (not shown) (not shown), and insulating electronic components (not shown) (transformers and photocouplers). The preamplifier 35 amplifies the voltage V2 input through the capacitor by the amplifier circuit, converts the amplified voltage into a detection signal S3 electrically insulated from the amplifier circuit by the insulating electronic component, and outputs the detection signal S3. To do. In this case, since the voltage V2 changes in proportion to the value of the current i, the detection signal S3 generated by amplifying the voltage V2 also changes in proportion to the value of the current i.

  As shown in FIG. 1, the main unit 3 includes an oscillation circuit 71, a filter circuit 72, an amplification circuit 73, a detection circuit 74, a polarity determination circuit 75, a voltage generation circuit 76, a transformer 77, a voltmeter 78, and an A / D conversion circuit. 79, a CPU 80, and a display device 81. In this case, the oscillation circuit 71, the filter circuit 72, the amplification circuit 73, the detection circuit 74, the polarity determination circuit 75, the voltage generation circuit 76, the transformer 77, and the voltmeter 78 constitute a voltage detection system circuit group together with the clamp sensor 2. The A / D conversion circuit 79 and the CPU 80 together with the clamp sensor 2 constitute a current detection system circuit group.

  The oscillation circuit 71 constituting the voltage detection system circuit group generates a drive signal S1 having a constant period T1 (frequency f1) and outputs the drive signal S1 to the clamp sensor 2. The oscillation circuit 71 generates a detection signal S10 having a period T2 (frequency f2 = 2 × f1) that is a half of the period T1 in synchronization with the drive signal S1, and outputs the detection signal S10 to the polarity determination circuit 75. In this case, in this example, the oscillation circuit 71 generates a sine wave signal as the drive signal S1 and the detection signal S10. The filter circuit 72 selectively allows the signal S3a having the same frequency as the capacitance modulation frequency f2 of the capacitance change function body 41 included in the detection signal S3 input from the clamp sensor 2 to pass therethrough.

  The amplifier circuit 73 amplifies the signal S3a input from the filter circuit 72 to a preset voltage level and outputs the amplified signal as a detection signal S4. In this example, since the capacity modulation frequency of the capacity change function body 41 is twice the frequency f1 of the drive signal S2, the frequency of the current i generated by the change in the capacitance C1 of the capacity change function body 41 is also the drive signal S1. The detection signal S3 generated by the preamplifier 35 includes the signal components of the frequencies f1 and f2, but the frequency of the detection signal S4 output from the amplifier circuit 73 is determined by the filter circuit 72. It becomes f2 by filtering. The detection circuit 74 generates the analog signal S5 by detecting the detection signal S4 using, for example, an envelope detection method. In this case, the amplitude (voltage value) of the analog signal S5 changes in proportion to the current value of the current i flowing through the variable capacitance circuit 33. The polarity determination circuit 75 receives the detection signal S10 and the detection signal S4 and detects the phase (polarity) of the detection signal S4 with respect to the detection signal S10. In addition, the polarity determination circuit 75 determines the polarity of the potential difference (V1−Vr) between the voltages V1 and Vr of the measurement target wire 4 and the case 31 based on the detected phase, and outputs a polarity signal S8 indicating this polarity. Generate and output. As an example, in this example, the polarity determination circuit 75 outputs the polarity signal S8 with the same polarity as the polarity of the potential difference (V1-Vr).

  The voltage generation circuit 76 generates and outputs a voltage signal S6. In this case, when the polarity of the input polarity signal S8 is “positive”, the voltage generation circuit 76 outputs the voltage of the output voltage signal S6 by an amount proportional to the amplitude (voltage value) of the input analog signal S5. On the contrary, when it is “negative”, it is decreased. The transformer 77 is an insulating transformer, and includes a primary winding 77a (number of turns: n1) and a secondary winding 77b (number of turns: n2> n1), and is configured as a step-up transformer. In this case, one end of each of the primary winding 77a and the secondary winding 77b is grounded (connected to the ground). The other end of the primary winding 77 a is connected to the voltage generation circuit 76, and the other end of the secondary winding 77 b is connected to the case 31 of the clamp sensor 2. With this configuration, the transformer 77 boosts the voltage signal S6 input to the primary winding 77a and outputs it as a reference potential signal S7 to the other end of the secondary winding 77b, and also to the case 31 of the clamp type sensor 2. Apply. In this way, the potential (reference potential) Vr of the case 31 is defined as the voltage of the reference potential signal S7. The voltmeter 78 measures the voltage (reference potential Vr) of the reference potential signal S7 and outputs digital data D3 indicating the voltage value to the CPU 80.

  The A / D conversion circuit 79 constituting the current detection circuit group receives the current detection signal S9 output from the current detection circuit 32, converts it into digital data D4 indicating the amplitude of the current detection signal S9, and sends it to the CPU 80. Output. The CPU 80 displays the voltage value of the measurement target wire 4 indicated by the digital data D3 on the display device 81, and calculates (measures) the current value of the current I1 flowing through the measurement target wire 4 based on the digital data D4. The current calculation process is executed, and the calculated current value is displayed on the display device 81. Further, the CPU 80 will be described later based on the calculated current value of the current I1 and the voltage value of the reference potential signal S7 (reference potential Vr) output from the voltmeter 78 (value indicated by the digital data D3). Thus, the power W1 supplied to the measurement target electric wire 4 is calculated (measured) and displayed on the display device 81.

  Next, the measurement operation of the voltage V1, the current I1, and the power W1 of the measurement target wire 4 by the power measuring device 1 will be described. In order to facilitate understanding of the invention, as an example, the voltage generation circuit 76 generates a zero-volt voltage signal S6 at the start of the measurement operation of the power measurement apparatus 1 (time t0), and then increases the voltage. Or decrease. Therefore, it is assumed that the transformer 77 starts to generate the reference potential signal S7 from zero volts as shown by a solid line in FIG.

  First, the clamp portion 5 of the clamp type sensor 2 is clamped on the measurement target electric wire 4. At this time, the clamp type sensor 2 is grasped by hand, and the clamp portion 5 is clamped to the measurement target electric wire 4, but in a state before the finger (for example, thumb) is put on the second operation lever 18, as shown in FIG. Further, the first operation lever 17 is urged by the spring 19 in a direction protruding from the sensor body 6, and the second operation lever 18 is urged by the spring 20 in a direction away from the first operation lever 17. For this reason, the movable sensor arm 15 is rotated in the direction of the fixed sensor arm 13 by the biasing force of the spring 19, and the other end (the left end in the figure) is the other end of the fixed sensor arm 13 (in the figure). The left end part) is in contact. Further, the pressing arm 16 is also rotated in the direction of the fixed sensor arm 13 by the urging force of the spring 20, and the other end portion (the left end portion in the figure) comes into contact with the intermediate portion on the inner peripheral surface of the fixed sensor arm 13. It is in a state.

  For this reason, a finger is put on the second operation lever 18, and the second operation lever 18 and the first operation lever 17 protruding from the opening 6 a are pushed into the sensor body 6. Accordingly, the movable sensor arm 15 and the pressing arm 16 are rotated in a direction away from the fixed sensor arm 13 against the urging force of the springs 19 and 20, and the clamp portion 5 is in the state shown in FIG. That is, the other ends of the fixed sensor arm 13 and the movable sensor arm 15 are separated from each other, and the fixed sensor arm 13 and the pressing arm 16 are separated from each other, so that the measurement target electric wire 4 can be clamped (open state). To do.

  Next, the measurement target electric wire 4 is introduced between the fixed sensor arm 13 and the movable sensor arm 15, and the finger hung on the second operation lever 18 is separated from the second operation lever 18. Thereby, the movable sensor arm 15 is rotated in the direction of the fixed sensor arm 13 by the biasing force applied to the first operation lever 17 from the spring 19, and the other end portion of the movable sensor arm 15 is the other end portion of the fixed sensor arm 13. (The clamp part 5 shifts from the open state to the closed state). Further, the pressing arm 16 is rotated in the direction of the fixed sensor arm 13 by the urging force applied from the spring 20 to the second operation lever 18. At this time, the measurement target electric wire 4 introduced between the fixed sensor arm 13 and the movable sensor arm 15 is brought close to the position where the detection electrode 12 is arranged on the fixed sensor arm 13 by the pressing arm 16 as shown in FIG. Pressed. In this way, the measurement target electric wire 4 can always be pressed by the pressing arm 16 in the vicinity of the position where the detection electrode 12 is disposed in the fixed sensor arm 13, and therefore the measurement target electric wire is interposed between the fixed sensor arm 13 and the movable sensor arm 15. Compared with a state in which the wire 4 is freely movable, the measurement wire 4 and the detection electrode 12 that are important when measuring the voltage V1 of the wire 4 to be measured, specifically, the core wire of the wire 4 to be measured A situation in which the capacitance value of the capacitance C0 formed between 4a and the detection electrode 12 fluctuates greatly is sufficiently avoided.

  Next, in the activated state of the power measuring device 1, in the voltage detection system circuit group, the oscillation circuit 71 of the main unit 3 starts generating the drive signal S1 and the detection signal S10, and the drive signal S1 is sent to the clamp sensor 2. In addition, the detection signal S10 is output to the polarity determination circuit 75. In the clamp type sensor 2, the drive circuit 42 of the variable capacitance circuit 33 converts the input drive signal S 1 into the drive signal S 2 and applies (outputs) between the connection points B and D of the capacitance change function body 41.

  In the capacitance change function body 41, the drive signal S2 applied between the connection points B and D is divided, and the first structural unit 51, the second structural unit 52, the third structural unit 53, and the fourth structural unit 53 are used. Applied to each of the structural units 54. In this case, as shown in FIG. 4, the potential of the connection point B becomes high with respect to the period Ta (the connection point D as a reference) in one cycle T1 of the drive signal S2, and the potential difference between them gradually increases. In the period), a reverse voltage in each first electrical element E1 is applied (reversely biased), and each capacitance of each first element 61 functioning as a capacitor gradually decreases. Specifically, the electrostatic capacity of each first element 61b that is reverse-biased in each of the first electrical elements E11 and E14, and each of the first electrical elements E12 and E13 that are reverse-biased. The capacitance of the first element 61a gradually decreases. Further, during the period Tb of one cycle T1 of the drive signal S2 (period in which the potential at the connection point B becomes high with the connection point D as a reference and the potential difference between the two gradually decreases), the drive signal S2 is reverse-biased. Each of the first elements 61, specifically, each of the first electric elements E11 and E14 has a capacitance of each first element 61b, and each of the first electric elements E12 and E13 has a capacitance of each of the first elements 61a gradually. To increase.

  Further, during the period Tc of one cycle T1 of the drive signal S2 (period in which the potential at the connection point B is low with respect to the connection point D and the potential difference between the two gradually increases), the drive signal S2 is reverse-biased. Each first element 61 that functions as a capacitor, specifically, each first element 61a in each first electrical element E11, E14, and each electrostatic element in each first element 61b in each first electrical element E12, E13. Capacity gradually decreases. Further, during the period Td of one cycle T1 of the drive signal S2 (a period in which the potential at the connection point B is low with respect to the connection point D and the potential difference between the two gradually decreases), the drive signal S2 is reverse-biased. The respective first elements 61a, specifically, the respective first electric elements E11 and E14, the respective first elements 61a, and the respective first electric elements E12 and E13, the respective capacitances of the respective first elements 61b are gradually increased. To increase. Note that the first elements 61a and 61b to which the forward voltage is applied (forward biased) among the first elements 61a and 61b included in each first electrical element E1 function equivalently as resistors. is doing. For this reason, the capacitance of each first electrical element E1 repeats decreasing and increasing twice within one cycle T1 of the drive signal S2.

  In this way, the capacitance of each first electrical element E1 included in each of the structural units 51 to 54 repeats increasing and decreasing twice each within one cycle T1 of the drive signal S2. The capacitance C1 (capacitance between the connection points A and B) of the capacitance changing function body 41 formed by synthesizing the capacitance is repeatedly increased and decreased twice. In other words, the variable capacitance circuit 33 continuously sets the capacitance C1 in synchronization with the cycle T1 of the input drive signal S2 and the cycle T2 (frequency f2 = 2 × f1) of the cycle T1 (main frequency). In the example, an operation that changes periodically is executed. In this case, as described above, the variable capacitance circuit 33 is connected in series between the case 31 and the detection electrode 12 with the current detector 34 interposed therebetween. 4 and the capacitance C0 formed between the detection electrodes 12 are connected in series between the measurement target electric wire 4 and the case 31. For this reason, when the electrostatic capacitance C1 periodically changes at the frequency f2 (capacitance modulation frequency), the electrostatic capacitance C2 between the measurement target electric wire 4 and the case 31 (series combination of the electrostatic capacitances C0 and C1). As shown in FIG. 4, the (capacitance) also changes in synchronization with the cycle T1 of the drive signal S2 and in a cycle T2 (frequency f2) which is a half of the cycle T1.

  In the variable capacitance circuit 33, as described above, variable capacitance diodes (or general diodes) having the same or substantially the same characteristics are used for the first elements 61 of the capacitance change function body 41. As a result, as a result, The product of the impedances of the first structural unit 51 and the third structural unit 53 and the product of the impedances of the second structural unit 52 and the fourth structural unit 54 are set to be the same or substantially the same. Therefore, since the capacitance changing function body 41 that is also a bridge circuit satisfies the equilibrium condition as the bridge circuit, the voltage component of the drive signal S2 (the voltage signal having the same frequency f1 as the drive signal S1) is connected to each of the connection points A, The electrostatic capacity C1 is changed with the period T2 in a state where there is almost no generation between C. Also included in each set of first electrical elements E11 and E14 included in each of the structural units 51 and 54 connected to the connection point A, and included in each of the structural units 52 and 53 connected to the connection point C. Since the two first electric elements E1 included in at least one of the first electric elements E12 and E13 are always functioning as a capacitor, the detection electrode 12 and the case 31 is connected in an AC manner via the variable capacitance circuit 33, but is maintained in a state where it is not short-circuited in terms of DC.

  For this reason, the capacitance C2 between the measurement target electric wire 4 and the case 31 periodically changes in the cycle T2 based on the periodic change in the capacitance C1 in the cycle T2, thereby changing the variable capacitance circuit 33. The current i (cycle T2) having an amplitude corresponding to the potential difference (V1−Vr) between the voltages V1 and Vr of the measurement target wire 4 and the case 31 flows. Specifically, the current i has a large amplitude (current value) when the potential difference (V1-Vr) is large, and a small current value when the potential difference (V1-Vr) is small.

  Therefore, as shown in FIG. 5, when the voltage V1 of the measurement target wire 4 is a positive voltage (time t0) and the power measuring device 1 starts a measurement operation, the potential difference (V1-Vr) is a positive voltage. Although not shown, the current i flows as an AC signal whose period is T2 and whose amplitude changes in accordance with the potential difference (V1-Vr). The preamplifier 35 amplifies the voltage V2 generated in the current detector 34 due to the current i and outputs it as a detection signal S3. In this case, the detection signal S3 mainly includes the same frequency component as the frequency f2 of the current i, and also includes the same frequency component as the frequency f1 of the drive signal S2.

  In the main unit 3, the filter circuit 72 selectively outputs the signal component of the frequency f2 included in the detection signal S3 as the signal S3a, and the amplifier circuit 73 amplifies the signal S3a to generate the detection signal S4. And output to the detection circuit 74. Next, the detection circuit 74 detects the input detection signal S4, generates an analog signal S5, and outputs the analog signal S5 to the voltage generation circuit 76. In this case, the analog signal S5 is a signal whose amplitude changes in proportion to the value of the potential difference (V1-Vr). Further, the polarity determination circuit 75 receives the detection signal S10 and the detection signal S4 and detects the phase of the detection signal S4 with respect to the detection signal S10, so that the polarity becomes the same as the polarity of the potential difference (V1-Vr). A signal S8 is generated and output to the voltage generation circuit 76.

  The voltage generation circuit 76 increases the voltage of the output voltage signal S6 by an amount proportional to the amplitude (voltage value) of the input analog signal S5 when the polarity of the input polarity signal S8 is “positive”. Conversely, when it is “negative”, it is decreased. Therefore, as shown in FIG. 5, when the voltage V1 of the measurement target wire 4 is a positive voltage (time t0) and the power measurement device 1 starts the measurement operation, the voltage signal S6 is initially zero volts, The reference potential signal S7 is also zero volts. As a result, the potential difference (V1−Vr) becomes a positive voltage, and thus the polarity of the polarity signal S8 also becomes positive. Therefore, the voltage generation circuit 76 increases the voltage value by an amount proportional to the amplitude of the input analog signal S5 and outputs the voltage signal S6. Next, the transformer 77 boosts the voltage signal S6 and outputs a reference potential signal S7 to be applied to the case 31. As a result, in the feedback loop composed of the current detector 34, the preamplifier 35, the filter circuit 72, the amplifier circuit 73, the detection circuit 74, the voltage generation circuit 76, and the transformer 77, there is a connection between the measurement target wire 4 and the case 31. Negative feedback is performed so that the potential difference (V1−Vr) gradually decreases (decreases).

  Therefore, the current value (amplitude) of the current i gradually decreases (decreases). Generally, in the power measuring device 1, the transient characteristic is set so that the convergence of the reference potential Vr to the voltage V1 of the measurement target wire 4 is completed in a short time. Therefore, the reference potential signal S7 converges at time t1 while overshooting the voltage V1, as shown in FIG. Note that when the reference potential Vr exceeds the voltage V1 of the measurement target wire 4 due to overshoot, the potential difference (V1−Vr) becomes a negative voltage, and thus the polarity of the polarity signal S8 also becomes negative. Therefore, the voltage generation circuit 76 decreases the voltage value by an amount proportional to the amplitude of the input analog signal S5 and outputs the voltage signal S6. Thereafter, the power measuring apparatus 1 continues the above-described feedback operation, so that the voltage value (reference potential Vr) of the reference potential signal S7 is within a certain deviation with respect to the voltage V1 of the measurement target electric wire 4 that changes. ). In this case, the reference potential signal S7 (and the voltage signal S6) is an AC signal that changes in synchronization with the voltage V1 of the measurement target wire 4. Therefore, the voltage value (reference potential Vr) measured by the voltmeter 78 after the lapse of a predetermined time (after the time (t1-t0) has elapsed from the start of measurement in this example) is equal to the voltage V1 of the measurement target wire 4. Become. The voltmeter 78 measures the voltage of the reference potential signal S7 in real time and outputs the voltage value (reference potential Vr) to the CPU 80 as digital data D3.

  On the other hand, in the current detection system circuit group, the current detection circuit 32 of the clamp type sensor 2 is in each of the magnetic cores 11 a and 11 b of the clamp unit 5 that clamps the measurement target electric wire 4 (in the closed magnetic circuit surrounding the measurement target electric wire 4. ), That is, a change in the magnetic flux passing through the detection coil 14, and generation of a current detection signal S 9 in which the current value of the current I 1 flowing through the measurement target wire 4 is proportional to the amplitude is started. The A / D conversion circuit 79 receives the current detection signal S9 output from the current detection circuit 32, converts it into digital data D4 indicating the amplitude of the current detection signal S9, and outputs it to the CPU 80.

  The CPU 80 causes the display device 81 to display the voltage value V1 of the measurement target wire 4 indicated by the digital data D3 output from the voltmeter 78 of the voltage detection system circuit group, and the A / D conversion circuit of the current detection system circuit group. Based on the digital data D4 output from 79, a current calculation process is executed to calculate (measure) the current value of the current I1 flowing through the measurement target electric wire 4, and the calculated current value is displayed on the display device 81. Further, the CPU 80 measures based on the calculated current value of the current I1 and the voltage value of the reference potential signal S7 (reference potential Vr) output from the voltmeter 78 (value indicated by the digital data D3). The electric power W1 supplied to the target electric wire 4 is calculated (measured) and displayed on the display device 81. Thus, the measurement of the voltage V1, the current I1, and the power W1 of the measurement target electric wire 4 is completed.

  Thus, in this clamp type sensor 2, the voltage V 1 of the measurement target wire 4 is not applied to the clamp portion 5 configured to be able to clamp the measurement target wire 4 and detecting the current I 1 flowing through the measurement target wire 4. A detection electrode 12 for measuring by contact is provided. Therefore, according to the clamp type sensor 2, unlike the configuration in which the voltage measurement probe and the current measurement probe are separated, the current I1 and the voltage V1 flowing in the measurement target electric wire 4 are measured by one clamping operation. Therefore, the current detection signal S9 and the detection signal S3 can be detected and output to the main unit 3, so that the measurement work can be greatly simplified.

  Moreover, in this clamp type sensor 2, it has the magnetic cores 11a and 11b which form the closed magnetic circuit which surrounds the measuring object electric wire 4, and the clamp part 5 is comprised, and the magnetic flux which passes the magnetic cores 11a and 11b (closed magnetic circuit) is comprised. A current detection circuit 32 that detects the current I1 based on the change is provided. Therefore, according to the clamp type sensor 2, the magnetic cores 11 a and 11 b of the clamp unit 5 can guide the magnetic flux to the detection coil 14 with little leakage, so that the current can be accurately detected based on the change of the magnetic flux in the detection coil 14. Can be detected.

  Further, in the clamp type sensor 2, a holding arm is provided between the fixed sensor arm 13 and the movable sensor arm 15 in a state in which one end is rotatably attached to the sensor main body 6 together with one end of the movable sensor arm 15. 16 is disposed. Therefore, according to the clamp type sensor 2, the measurement electrode 4 clamped by the fixed sensor arm 13 and the movable sensor arm 15 holds the measurement electrode 4 at the other end of the holding arm 16, and the position of the detection electrode 12 on the fixed sensor arm 13. Can be pressed in the vicinity. For this reason, compared with the structure which clamps the measurement object electric wire 4 in the state to which the measurement object electric wire 4 can move freely between the fixed sensor arm 13 and the movable sensor arm 15, the voltage V1 of the measurement object electric wire 4 is not contacted. The variation in the capacitance value of the capacitance C0 formed between the detection electrode 12 and the measurement target wire 4 (specifically, the core wire 4a of the measurement target wire 4), which is important when measuring with the above, can be reduced. As a result, the voltage V1 of the measurement target electric wire 4 can be accurately measured in a non-contact manner. As a result, the power W1 can also be measured with high accuracy.

  In addition, this invention is not limited to said structure. For example, in the clamp type sensor 2 described above, the detection coil 14 is wound around the magnetic core 11 b and disposed in the movable sensor arm 15, but is wound around the magnetic core 11 a and disposed in the fixed sensor arm 13. You can also. Further, although one of the pair of sensor arms is fixed to the sensor body 6 as the fixed sensor arm 13, although not shown, both the pair of sensor arms are movable with the same configuration as the movable sensor arm 15. It can also be a sensor arm. In addition, one end is fixed to the sensor main body 6 and the detection electrode 12 is disposed therein, and one end is rotatably attached to the sensor main body 6 and the other end is fixed. Although the example provided with the movable sensor arm 15 comprised so that contact / separation was possible with respect to the other end part of the sensor arm 13 was demonstrated, although not shown in figure, while one end part is fixed to the sensor main-body part 6, and a magnetic core A fixed sensor arm 13 in which 11a is disposed, a magnetic core 11b and a detection electrode 12 are disposed, and one end is rotatably attached to the sensor body 6 and the other end is a fixed sensor. A movable sensor arm 15 configured to be able to come into contact with and separate from the other end of the arm 13, and a fixed sensor arm having one end rotatably attached to the sensor main body 6 together with one end of the movable sensor arm 15. 3 and the movable sensor arm 15, and the measurement target electric wire 4 clamped by the fixed sensor arm 13 and the movable sensor arm 15 is arranged at the other end of the position of the detection electrode 12 in the movable sensor arm 15. The clamp portion 5 can also be configured with a pressing arm 16 that presses in the vicinity. Further, in place of the configuration in which the detection coil 14 detects a change in magnetic flux in a closed magnetic circuit formed so as to surround the measurement target wire 4 by the magnetic cores 11a and 11b, a magnetoelectric conversion element such as a Hall element is used in the present invention. It can also be set as the structure which uses and detects as a part of electric current detection part. Further, without using the magnetic cores 11a and 11b, the detection coil 14 may be configured as an air-core coil and disposed in the sensor arms 13 and 15.

  Further, although an example in which the detection electrode 12 is disposed on one of the fixed sensor arm 13 and the movable sensor arm 15 has been described, although not illustrated, one end is fixed to the sensor body 6 and the magnetic core 11a is A fixed sensor arm 13 disposed inside and a magnetic core 11b are disposed inside, one end of which is rotatably attached to the sensor body 6, and the other end is the other end of the fixed sensor arm 13. A movable sensor arm 15 configured to be movable toward and away from the sensor and a detection electrode 12 are disposed therein, and one end thereof is rotatably attached to the sensor body 6 together with one end of the movable sensor arm 15. The measurement target electric wire 4 disposed between the fixed sensor arm 13 and the movable sensor arm 15 and clamped by the fixed sensor arm 13 and the movable sensor arm 15 is connected at the other end. It is also possible to configure the clamping portion 5 and a holding arm 16 for pressing on one of the constant sensor arm 13 and the movable sensor arm 15.

  Further, in the clamp type sensor 2 described above, the clamp unit 5 is opened from the closed state to the open state using the two divided magnetic cores 11a and 11b so that the measurement target electric wire 4 can be easily clamped and opened. However, instead of the two divided magnetic cores 11a and 11b, one toroidal magnetic core is used instead of the two divided magnetic cores 11a and 11b. 91 may be used to constitute the clamp portion 5A as a magnetic path forming portion in the present invention, or a magnetic core 92 (for example, U) having a gap in part as in the clamp type sensor 2B shown in FIG. The clamp part 5B as a magnetic path formation part in this invention can also be comprised using a character-shaped core. In addition, about the structure same as the clamp type sensor 2, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  In addition, as an example of a circuit configuration capable of measuring the voltage V1 of the measurement target wire 4 using the detection electrode 12 in a non-contact manner, by using the capacitance changing function body 41 configured by a diode, the voltage V1 is a DC voltage and Although it is configured to be able to measure any AC voltage, when the voltage V1 is an AC voltage, for example, Japanese Patent No. 3302377, Japanese Patent Application Laid-Open No. 10-31037, Japanese Patent Application Laid-Open No. 2002-71726, and Various known circuit configurations such as those disclosed in Japanese Patent Application Laid-Open No. 2003-28900 can also be employed.

1 is a configuration diagram of a power measuring device 1. FIG. 3 is a circuit diagram of a variable capacitance circuit 33, a current detector 34, and a preamplifier 35 of the power measuring device 1. FIG. 3 is a circuit diagram of a capacity change function body 41 in the power measuring device 1. FIG. 6 is a relationship diagram between a drive signal S2 and a capacitance C2 for explaining the operation of the capacitance change function body 41. FIG. It is a wave form diagram which shows the relationship between the voltage V1 and reference potential signal S7. It is a partially cutaway front view for demonstrating the structure of the clamp type sensor 2 (closed state (clamp state)). It is a front view for demonstrating the structure of the clamp type sensor 2 (open state (unclamped state)). It is a front view for demonstrating the structure of 2 A of clamp type sensors. It is a front view for demonstrating the structure of the clamp type sensor 2B.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric power measuring device 2, 2A, 2B Clamp type sensor 4 Electric wire to be measured 5, 5A, 5B Clamp part 6 Sensor main part 11a, 11b, 91, 92 Magnetic core 12 Detection electrode 13 Fixed sensor arm 15 Movable sensor arm 16 Pressing arm 32 Current detection circuit I1 Current S9 Current detection signal

Claims (5)

A clamp unit configured to be capable of clamping the measurement target electric wire and detecting a current flowing through the measurement target electric wire,
The clamp type sensor provided with the detection electrode which is arrange | positioned at the said clamp part and detects the voltage of the said measurement object electric wire. The clamp part is configured to have a magnetic path forming part surrounding the measurement target electric wire,
The clamp type sensor of Claim 1 provided with the electric current detection part which detects the said electric current based on the change of the magnetic flux which passes through the said magnetic path formation part. The current detection unit includes a sensor main body disposed inside,
The clamp part includes a fixed sensor arm having one end fixed to the sensor body and the detection electrode disposed therein, and one end rotatably attached to the sensor body. A movable sensor arm configured to be movable toward and away from the other end of the fixed sensor arm, and one end of which is pivotally attached to the sensor main body together with the one end of the movable sensor arm. An arrangement position of the detection electrode in the fixed sensor arm at the other end of the measurement target electric wire, which is arranged between the sensor arm and the movable sensor arm and clamped by the fixed sensor arm and the movable sensor arm. The clamp type sensor according to claim 2, further comprising a pressing arm that presses in the vicinity of. The current detection unit includes a sensor main body disposed inside,
The clamp part has a fixed sensor arm having one end fixed to the sensor main body part, the detection electrode is disposed inside, and one end part rotatably attached to the sensor main body part. A movable sensor arm configured to be movable toward and away from the other end of the fixed sensor arm, and one end of which is pivotably attached to the sensor body together with the one end of the movable sensor arm. An arrangement position of the detection electrode in the movable sensor arm at the other end of the measurement target electric wire which is arranged between the sensor arm and the movable sensor arm and is clamped by the fixed sensor arm and the movable sensor arm. The clamp type sensor according to claim 2, further comprising a pressing arm that presses in the vicinity of. The current detection unit includes a sensor main body disposed inside,
The clamp part has a fixed sensor arm with one end fixed to the sensor body part, and one end part rotatably attached to the sensor body part, and the other end part with respect to the other end part of the fixed sensor arm. The movable sensor arm is configured to be able to contact and separate, and the detection electrode is disposed inside, and one end of the movable sensor arm is rotatably attached to the sensor main body together with the one end of the movable sensor arm. One of the fixed sensor arm and the movable sensor arm, which is disposed between the sensor arm and the movable sensor arm and clamped by the fixed sensor arm and the movable sensor arm at the other end. The clamp type sensor according to claim 2, further comprising a pressing arm that presses against one side.

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