JP2013120098A - Voltage detection apparatus and power detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage detection apparatus capable of detecting voltage more accurately as compared with a conventional apparatus, and to provide a power detection apparatus capable of detecting electric power or electric energy more accurately as compared with a conventional apparatus.SOLUTION: In a power detection apparatus 10, a balanced amplifier 37 mainly composed of operational amplifiers OP3, OP4 is connected to the input side of a differential amplifier circuit 38, so that an input becomes high impedance and detection voltages detected by voltage detection electrodes 18, 18 can be entered without reducing the voltages. Further all circuits included in the power detection apparatus 10 are grounded to a common ground member 94, so that influence on voltage detection results, which is caused by a potential difference between grounds which may be generated when grounding the circuits to respective grounds, can be suppressed. Consequently the influence on voltage detection results, caused by surrounding environments of the voltage detection electrodes 18, 18, can be suppressed, voltages can be detected more accurately as compared with a conventional apparatus, and also electric power and electric energy can be accurately detected.

Description

  The present invention relates to a voltage detection device capable of detecting the voltage of power transmitted through a single-phase two-wire or single-phase three-wire power line in a non-contact state with the conductor of the power line, and the power transmitted through these power lines. It is related with the electric power detection apparatus which can detect the electric power or electric energy which is touchlessly.

  Conventionally, as a voltage detection device of this type, a voltage between the first power line and the neutral line is obtained by electrostatically coupling a voltage detection electrode to the first and second power lines of the single-phase three-wire system and the neutral line. A voltage detection device that detects a voltage between a second power line and a neutral line and obtains a difference between the detected voltages as a voltage of power transmitted through the power line is known (see, for example, Patent Document 1). ).

Japanese Patent Laying-Open No. 2010-181378 (FIG. 1, paragraphs [0016] and [0022])

  However, in the above-described conventional voltage detection device, the detection results of the voltages on the first and second power lines are affected by the environment around the voltage detection electrodes, and the voltage cannot be accurately detected. There was a problem. Further, since the voltage detected by the voltage detection device is also used for power detection, there has been a problem that power cannot be detected accurately.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a voltage detection device capable of detecting a voltage more accurately than in the past and a power detection device capable of detecting power or a power amount more accurately than in the past.

  In order to achieve the above object, a voltage detection device according to the invention of claim 1 is the first and second power lines having a 180 ° voltage phase shift in a single-phase two-wire or single-phase three-wire power line. A voltage detection device for detecting a voltage between the first and second voltage detection electrodes that can be electrostatically coupled to the first and second power lines via their insulating coatings; A shield electrode that covers the second voltage detection electrode, a differential amplifier circuit that amplifies the potential difference between the first and second voltage detection electrodes, and between the first and second power lines based on the output of the differential amplifier circuit And a voltage detection processing circuit including a voltage calculation circuit for calculating the voltage of the circuit, wherein a circuit portion and a shield electrode that are connected to the first and second voltage detection electrodes in the voltage detection processing circuit are grounded to a common ground. It has the characteristics.

  According to a second aspect of the present invention, in the voltage detection device according to the first aspect, a balanced amplifier having first and second operational amplifiers is provided on the input side of the differential amplifier circuit. The first voltage detection electrode is connected to the positive input of the operational amplifier, and one input of the differential amplifier circuit is connected to the output of the first operational amplifier, and the second voltage detection electrode is connected to the positive input of the second operational amplifier. And the other input of the differential amplifier circuit is connected to the output of the second operational amplifier, and the negative inputs of the first and second operational amplifiers are connected to each other via a resistor. A voltage dividing circuit that divides the positive inputs of the two operational amplifiers in a one-to-one relationship is provided, and the voltage dividing point of the voltage dividing circuit is higher than the ground grounded in common with the shield electrode and the voltage detection processing circuit. Bi-bias biased to potential Characterized in place of providing a scan circuit.

  According to a third aspect of the present invention, in the voltage detection device according to the first or second aspect, higher harmonics having a higher frequency than the first-order wave included in the voltage wave applied to the first and second power lines are equalized. It is characterized in that an equalizer circuit is provided on the output side of the differential amplifier circuit.

  According to a fourth aspect of the present invention, in the voltage detection device according to any one of the first to third aspects, a differential amplifier circuit is provided between the differential amplifier circuit and the voltage arithmetic circuit in the voltage detection processing circuit. Is characterized in that a transmission circuit and a reception circuit for transmitting / receiving the output of the optical signal or radio signal as a radio signal are provided so that the differential amplifier circuit and the voltage calculation circuit are not electrically connected.

  According to a fifth aspect of the present invention, in the voltage detection device according to the fourth aspect, the power detection circuit includes a power supply circuit that receives power by electromagnetic induction coupling to the first or second power line and supplies power to the differential amplifier circuit side from the transmission circuit. However, it has characteristics.

  According to a sixth aspect of the present invention, in the voltage detecting device according to the fifth aspect, a coil is wound around one or both of a pair of split cores obtained by splitting a ring-shaped saturable core into two, and a power line is It is characterized in that the power supply circuit is provided with an electromagnetic induction coupling portion that can be sandwiched between the pair of split cores.

  According to a seventh aspect of the present invention, in the voltage detection device according to any one of the first to sixth aspects, a shield electrode is provided separately for each of the first and second voltage detection electrodes, The shield electrode is formed of a pair of metal casings that are open on one side, and is formed on one metal casing, and a united holding means that holds the edges of the opening of the pair of metal casings in a combined state. A shielded cable insertion hole, and a power line receiving recess that is formed in a joint portion between the metal casings and constitutes a power line insertion hole through which the first or second power line can be inserted. The voltage detection electrode is fixed to the inner surface of the metal housing via an insulating member and arranged so as to be directed to the side surface of the first or second power line inserted through the power line insertion hole, and is inserted into each shielded wire insertion hole. The first and second voltages by the shielded cable core wire With the output electrode is connected to a differential amplifier circuit, having the features of the first and second shield electrode by the shield wire of the shield cable, at grounded to a common ground with the voltage detection processing circuit.

The invention according to claim 8 is the voltage detection device according to any one of claims 1 to 6, wherein one shield electrode is provided in common for the first and second voltage detection electrodes, An union holding means configured to be composed of a pair of open metal casings and held in a combined state in which the edges of the opening of the pair of metal casings are joined together, and a shield cable insertion formed on one of the metal casings The first and second voltage detections each include a hole and two pairs of power line insertion holes that are formed in a joint portion between the metal casings and can be inserted in a state where the first and second power lines are separated. The electrode is fixed to the inner surface of one metal casing of the pair of metal casings via an insulating member so as to be directed to the side surfaces of the first and second power lines inserted through the pair of power line insertion holes. The first wire is connected by the core wire of the pair of shielded cables inserted in the shielded wire insertion hole. Beauty second voltage detection electrode as well as connected to a differential amplifier circuit, having the features a shield electrode by the shield wire of the pair of shielded cable to was grounded to common ground of the voltage detection processing circuit.

  The invention of claim 9 is the voltage detection device according to claim 7 or 8, wherein the first and second voltage detection electrodes are formed in a U-shaped groove, and the two sides of the U-shape are a pair of metal casings. It is characterized by being arranged so as to face each other in the facing direction.

  A tenth aspect of the present invention is the voltage detection apparatus according to any one of the first to sixth aspects, wherein one shield electrode is provided in common for the first and second voltage detection electrodes, An union holding means configured by an open pair of metal casings and held in an union state in which the edges of the open ends of the pair of metal casings are joined together, and a shield cable insertion hole in which each metal case is formed And a state in which the first and second power lines are lined up in the facing direction between the pair of metal casings, which is formed at a joint portion between the metal casings and can be inserted through the first and second power lines together. And a pair of power line insertion holes that can be held on the power line. Each of the first and second voltage detection electrodes is divided into a pair of metal casings and fixed via an insulating member, and the first and second power lines inserted through the pair of power line insertion holes The first and second voltage detection electrodes are connected to the differential amplifier circuit by the core wire of the shield cable that is disposed so as to be opposed to each other and is inserted into the shield wire insertion hole of each metal housing, and the shield wire of the shield cable This is characterized in that each metal casing is grounded to a common ground with the voltage detection processing circuit.

  According to an eleventh aspect of the present invention, in the voltage detection device according to any one of the seventh to tenth aspects, the first and the second metal casings are fixed to a pair of metal casings and the first and second metal casings are combined. It is characterized in that it has a pair of insulating cushion members that sandwich the second power line.

  A power detection device according to a twelfth aspect of the present invention is directed to the voltage detection device according to any one of the first to eleventh aspects of the invention and the first or second power line via the insulation coating. A current detection coil capable of electromagnetic induction coupling, a current detection processing circuit for calculating a current flowing in the first and second power lines based on an induced current flowing in the current detection coil, a calculation result of the current detection processing circuit, and a voltage detection A power detection processing circuit for calculating the power or the amount of power transmitted through the first and second power lines from the calculation result of the voltage detection processing circuit in the device, and the first of the current detection processing circuit and the power detection processing circuit. The circuit portion and the shield electrode, which are electrically connected to the first and second voltage detection electrodes, are characterized by being grounded to a common ground.

  According to a thirteenth aspect of the present invention, in the power detection device according to the twelfth aspect, the current detection processing circuit includes an amplifier circuit that amplifies a voltage signal corresponding to the induced current flowing through the current detection coil, and an output of the amplifier circuit. And a current calculation circuit for calculating a current flowing through the first and second power lines based on the output of the amplification circuit between the amplification circuit and the current calculation circuit in the current detection processing circuit. A transmission circuit and a reception circuit for transmitting and receiving are provided to make the amplifier circuit and the current arithmetic circuit non-conductive, and the differential amplification circuit and the voltage arithmetic circuit in the voltage detection processing circuit are differentially amplified. It is characterized in that a transmission circuit and a reception circuit that transmit and receive an optical signal or a radio signal as an output of the circuit are provided to make the differential amplifier circuit and the voltage calculation circuit non-conductive.

[Inventions of Claims 1 and 12]
In the voltage detection device according to claim 1, since the first and second voltage detection electrodes electrostatically coupled to the first and second power lines for voltage detection are covered with the shield electrode, noise is generated in the voltage detection electrode. Is difficult to be granted. In addition, the voltage detection processing circuit of the voltage detection device of the present invention differentially amplifies the potential difference between the first and second voltage detection electrodes, so that the common-mode voltage of the first and second voltage detection electrodes at that time Noise is canceled out. Furthermore, in the voltage detection apparatus of the present invention, the circuit part and the shield electrode that are connected to the first and second voltage detection electrodes in the voltage detection processing circuit are grounded to a common ground, so that they are grounded to separate grounds. The influence on the detection result of the voltage due to the potential difference between the grounds that may occur can be suppressed. As a result, in the voltage detection device of the present invention, it is possible to detect the voltage more accurately than in the past by suppressing the influence on the voltage detection result by the environment around the voltage detection electrode. Moreover, since the electric power detection apparatus of Claim 12 detects electric power or electric energy using the detection result of the voltage detection apparatus of this invention, it can detect electric power or electric energy more correctly than before.

[Invention of claim 2]
According to the second aspect of the present invention, a balanced amplifier having first and second operational amplifiers is provided on the input side of the differential amplifier circuit, and the first and second voltage detection electrodes are connected to the positive inputs of the operational amplifiers. The input of the voltage detection processing circuit becomes high impedance. Thereby, the detection voltage by the 1st and 2nd voltage detection electrode which became high impedance between the 1st and 2nd electric power lines by electrostatic coupling can be taken in into a voltage detection processing circuit, without reducing. The balanced amplifier also cancels out the common-mode voltage noise of the first and second voltage detection electrodes.

[Invention of claim 3]
The above-described voltage detection device of the present invention is generally provided to apply a bias voltage to the input side of the differential amplifier circuit and a capacitor that is a capacitance component between the power line and the first and second voltage detection electrodes. A CR type high-pass filter circuit is configured by the resistor. The high-pass filter circuit transmits higher harmonics contained in the voltage wave to be detected with higher gain as the frequency increases. On the other hand, in the configuration of the third aspect, the equalizer circuit for equalizing higher harmonics than the primary wave included in the voltage wave is provided on the output side of the differential amplifier circuit. By correcting the error component due to the gain difference for each frequency generated by the high-pass filter circuit, the voltage detection accuracy can be increased.

[Inventions of Claims 4, 5 and 6]
In the voltage detection device according to claim 4, the differential amplification circuit and the voltage calculation circuit in the voltage detection processing circuit and the voltage calculation circuit and the first and second voltage detection electrodes are made non-conductive. Therefore, since the voltage calculation circuit is separated from the first and second voltage detection electrodes, the degree of freedom in the configuration of the voltage calculation circuit is increased. Thereby, for example, a general-purpose personal computer or the like can be used as the voltage calculation circuit. According to the configuration of claim 5, it is easy to secure the power supply on the differential amplifier circuit side in the voltage detection processing circuit. Further, according to the configuration of claim 6, since the power supply circuit is electromagnetically coupled to the current of the first or second power line by the coil wound around the saturable core, the power circuit is connected to the first or second power line. Even if the transmitted power changes greatly, the power supply circuit can stably receive power from the first or second power line.

[Inventions of Claims 7, 8, 9, 10 and 11]
In the configuration of the seventh aspect, since the shield electrode is provided separately for each of the first and second voltage detection electrodes, the mutual influence between the first and second voltage detection electrodes in voltage detection can be suppressed. . In the configuration of the eighth aspect, since one shield electrode is provided in common for the first and second voltage detection electrodes, a compact configuration can be achieved. In addition, since the first and second power lines are inserted into and separated from the two pairs of power line insertion holes formed in the joint portion between the metal casings, the separated first and second power lines are It is also possible to suppress the mutual influence between the first and second voltage detection electrodes that are addressed. According to the configuration of the ninth aspect, the metal casings can be combined with each other by hooking the electric wires on the first and second voltage detection electrodes having the U-shaped grooves fixed to the one metal casing. The voltage detection device can be easily attached to the first and second power lines. Further, according to the configuration of claim 10, when the first and second power lines are integrally fixed with a common insulating coating in a state where the first and second power lines are arranged side by side, the first and second power lines are not separated. The voltage detection device can be attached to the power lines. According to the configuration of the eleventh aspect, since the first and second power lines are sandwiched and fixed by the pair of cushion members fixed to the pair of metal casings, the first and second voltage detections are performed. The positions of the first and second power lines with respect to the electrodes are stabilized, and the voltage detection accuracy is increased.

[Invention of Claim 13]
In the power detection device according to the thirteenth aspect, since the amplifier circuit and the current arithmetic circuit and the differential amplifier circuit and the voltage arithmetic circuit are not electrically connected, the voltage arithmetic circuit and the current arithmetic circuit are the first ones. In addition, the voltage calculation circuit and the current calculation circuit are separated from the second voltage detection electrode, thereby increasing the degree of freedom of the configuration. Accordingly, for example, a general-purpose personal computer or the like can be used as the voltage calculation circuit and the current calculation circuit.

The perspective view of the electric power detection apparatus which concerns on 1st Embodiment of this invention. Exploded perspective view of voltage sensor Perspective view of the voltage sensor attached to the power line Circuit diagram of current detection amplifier circuit Circuit diagram of power supply circuit (A) Current waveform of power line, (B) Magnetic flux waveform in saturable core, (C) Voltage waveform after rectification and smoothing processing in power supply circuit (A) The output waveform of the current detection amplifier circuit, (B) a graph showing the relationship between the current value of the power line and the output waveform of the current detection amplifier circuit, Circuit diagram of voltage detection amplifier circuit (A) Circuit portion provided on the input side of the voltage detection amplifier circuit, (B) Circuit diagram of a high-pass filter circuit substantially identical to the circuit portion. Graph showing frequency characteristics of gain of high-pass filter circuit (A) Detected voltage waveform by power detector, (B) Detected current waveform, (C) Detected power waveform The exploded perspective view of the voltage sensor of a 2nd embodiment. Sectional drawing of the voltage sensor of 3rd Embodiment Sectional drawing of the voltage sensor of 4th Embodiment Conceptual diagram of clamper of fifth embodiment

[First Embodiment]
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 conceptually shows the entire power detection apparatus 10 according to the present invention. The power detection apparatus 10 includes a measurement terminal 11 and a data processing terminal 12. The measurement terminal 11 is attached to, for example, power lines L1 and L2 of a single-phase three-wire type or single-phase two-wire commercial power source drawn into a residence from a utility pole, etc. Connected to. Then, the measurement terminal 11 detects the voltage between the power lines L1 and L2 and the current flowing through the power line L1, and the data processing terminal 12 that wirelessly receives the detected data from the measurement terminal 11 calculates the power, and the Internet. Send to the power company through the line.

  The measurement terminal 11 of the power detection device 10 is provided with a pair of voltage sensors 13 and 13 for voltage detection. As shown in FIG. 2, the voltage sensor 13 has a structure in which the voltage detection electrode 18 is surrounded by the shield electrode 14. The shield electrode 14 is composed of a pair of box-shaped metal housings 15, 15 whose one surface is open. A pair of fixing flanges 15F, 15F project from the pair of opposing sides of the opening edge of the opening 15A to the side of each metal casing 15, and screws are inserted into the pair of fixing flanges 15F, 15F. The holes 15B and 15B are formed to penetrate therethrough. Then, as shown in FIG. 3, the screw N1 inserted through the screw insertion holes 15B and 15B and the nut (not shown) are screwed together in the combined state in which the fixing flanges 15F and 15F of the metal casings 15 are overlapped. As a result, the metal casings 15 and 15 are held in the combined state. These screws N1 and nuts correspond to “union holding means” according to the present invention.

  As shown in FIG. 2, semicircular power line receiving recesses 15C and 15C are formed in the center of a pair of opposing sides where the fixing flanges 15F and 15F are not formed among the opening edges of each metal casing 15. Yes. As shown in FIG. 3, when the metal casings 15 and 15 are combined, the pair of power line receiving recesses 15C and 15C face each other to form the power line insertion hole 14A according to the present invention.

  As shown in FIG. 2, a pair of cushion members 16 are provided inside each metal casing 15 along the side wall having the power line receiving recesses 15 </ b> C and 15 </ b> C. These cushion members 16 are made of, for example, a rectangular parallelepiped insulating elastomer (rubber material), and are fixed to the inner back surface of the metal housing 15 with a double-sided tape or an adhesive. One end surface is substantially flush with the opening surface of the metal housing 15. In addition, as the elastomer constituting the cushion member 16, an elastomer having a low dielectric constant and a low conductivity, and those dielectric constant and a conductivity that hardly change with a temperature change is used.

  A voltage detection electrode 18 is fixed at the center of the inner back surface of one metal casing 15. The voltage detection electrode 18 is formed of a strip-shaped sheet metal curved in a U-shaped groove shape, and a U-shaped piece faces the inner back surface of the metal housing 15 in parallel, and is curved in a U-shaped semicircular shape. With the central axis of the portion arranged on the line connecting the centers of the power line receiving recesses 15C and 15C, the inner depth of the metal casing 15 is interposed via the insulating support block 17 (corresponding to the “insulating member” according to the present invention). It is fixed to the center of the surface with double-sided tape or adhesive. The insulating support block 17 is made of, for example, the same elastomer as the cushion member 16.

  Further, a shielded wire insertion hole 15 </ b> D is formed through the side of the insulating support block 17 in one of the metal housings 15. The shield cable 19 is inserted into the shield wire insertion hole 15D, and the core wire 19A of the shield cable 19 is soldered or brazed to the outer surface of the voltage detection electrode 18, while the shield wire 19B of the shield cable 19 is connected to the metal casing. The inner surface of 15 is soldered or brazed.

  The voltage sensors 13 and 13 configured as described above are attached to the power lines L1 and L2 as follows, for example. That is, the metal housings 15 and 15 are separated, and the power line L1 (or the power line L2) is housed in the voltage detection electrode 18 of one metal housing 15. Then, two portions of the power line L1 on both sides of the voltage detection electrode 18 are arranged at positions facing the power line receiving recesses 15C and 15C, and the cushion members 16 and 16 are slightly bent, so that the power line L1 is made of metal. The housing 15 is temporarily secured. In this state, as shown in FIG. 3, the metal casings 15 and 15 are combined with each other and fixed with screws N1 and nuts. Thus, the power line L1 passes through the shield electrode 14 through the power line insertion hole 14A, and a part of the power line L1 is held in the groove of the voltage detection electrode 18 in the shield electrode 14.

  As shown in FIG. 1, the measurement terminal 11 includes a first clamper 20 for current detection and a second clamper 23 for power reception (corresponding to the “electromagnetic induction coupling portion” of the present invention). Yes. The first clamper 20 is conceptually shown in FIG. 4, and includes a current detection unit 20H formed by winding a current detection coil 22 around one of a pair of semicircular split cores 21A and 21B. The structure is built into the mechanism. The core 21 is made of, for example, a high magnetic permeability magnetic material (for example, ferrite or silicon steel plate), and the number of turns of the current detection coil 22 is, for example, 100 to 200 turns. The clamp mechanism can be opened and closed between the split cores 21A and 21B, and can be held in a state where the split cores 21A and 21A are closed to form a ring-shaped core 21. Then, the power line L1 is inserted inside the core 21 and attached to the power line L1.

  The second clamper 23 is conceptually shown in FIG. 5 and, like the first clamper 20, is a pair of semicircles that form a ring-shaped core 24 (corresponding to the “saturated core” of the present invention). The power receiving unit main body 23H formed by winding the power receiving coil 25 around one of the divided cores 24A and 24B is incorporated in a clamp mechanism (not shown). However, unlike the core 21 of the first clamper 20, the core 24 of the second clamper 23 is made of, for example, a saturable magnetic material (eg, amorphous). The number of turns of the power receiving coil 25 is, for example, 800 to 1000 turns. Then, the power line L1 is inserted inside the core 24 and attached to the power line L1. Note that the measurement terminal 11 is not attached to the single-phase three-wire neutral line N (see FIGS. 1 and 8).

  As shown in FIG. 1, a power supply circuit 30, a current detection amplification circuit 40, a voltage detection amplification circuit 50, an A / D converter 95, a microcomputer 96 (hereinafter simply referred to as “microcomputer 96”) and a transmission are transmitted to the measurement terminal 11. A circuit 97 is provided.

  As shown in FIG. 5, the power supply circuit 30 includes a bridge rectifier circuit 31, a smoothing capacitor C1, a DC / DC converter 32, in order from the input side to which the power receiving coil 25 of the second clamper 23 is connected toward the output side. The smoothing capacitor C2 is provided. The power supply circuit 30 is grounded to a ground member 94 provided in the measurement terminal 11 and outputs a DC voltage having a potential difference of Vcc with respect to the ground member 94. All circuits of the measurement terminal 11 receive power from the power supply circuit 30 and are grounded to the common ground member 94. The shield electrodes 14 and 14 are also grounded to the ground member 94 via the shield wire 19B of the shield cable 19. In addition, the ground member 94 is comprised by the case (not shown) etc. which the measurement terminal 11 has, for example.

  Since the power supply circuit 30 is electromagnetically coupled to the power line L1 via the saturable magnetic core 23, the power supply circuit 30 is hardly affected by the magnitude of the current flowing through the power line L1, and receives power stably from the power line L1. Power supply can be performed. Specifically, as shown in FIG. 6A, for example, when the current I flowing through the power line L1 is 0.1 [A] and the current I is 100 [A], When the current I is 0.1 [A] as shown by the broken line in FIG. 6A, the core 24 is not magnetically saturated, and the magnetic flux H in the core 24 is shown by the broken line in FIG. As shown, it is a sine wave with the same period as the current waveform of the power line L1.

  On the other hand, as shown by the solid line in FIG. 6A, when the current I is 100 [A], the core 24 is magnetically saturated early in a period in which the current I is shorter than a half cycle, and the magnetic flux H in the core 24 As shown by the solid line in FIG. 6B, the change of 現 れ る appears as a pulse wave having a high wave height but a small DUTY compared to a sine wave when the current I is 0.1 [A]. Further, the voltage Va (see FIG. 5) between both terminals of the power receiving coil 25 is the same as the magnetic flux H shown in FIG. 6B depending on whether the current I of the power line L1 is 0.1 [A] or 100 [A]. Similarly, it becomes a sine wave or a pulse wave.

  As a result, even if the current I changes 1000 times, such as a change from 0.1 [A] to 100 [A], the voltage Va (see FIG. 5) between both terminals of the power receiving coil 25 is rectified and smoothed. The change in the voltage Vb (see FIGS. 5 and 6C) after processing is slight. That is, as described at the beginning, the power supply circuit 30 is hardly affected by the magnitude of the current flowing through the power line L1, and can stably receive power from the power line L1 and perform stable power feeding.

  As shown in FIG. 4, the current detection amplifier circuit 40 is a differential amplifier circuit 36 mainly composed of an operational amplifier OP1. And it connects so that the voltage of the both ends of resistance R1 connected between the both ends of the current detection coil 22 may be input into operational amplifier OP1. One end of the resistor R1 is grounded to the ground member 94 via the capacitor C3, and a bias voltage (Vcc / 2) is applied to the other end of the resistor R1 via the resistor R2. As a result, the detection result of the current I flowing through the power line L1 is output from the operational amplifier OP1 as a pulsating voltage signal whose amplitude is centered on the bias voltage (Vcc / 2), as shown in FIG. 7A. The output of the operational amplifier OP1 is taken into the microcomputer 96 as the output of the current detection amplifier circuit 40 through the A / D converter 95 as shown in FIG.

  Further, the current detection amplifier circuit 40 is provided with a gain switching circuit 34 for switching the gain of the differential amplifier circuit 36 to three stages of high, medium and low. The gain switching circuit 34 is provided with an electronic switch 35, and the electronic switch 35 is controlled by a microcomputer 96. Specifically, the gain is reduced when the wave height of the pulsating voltage signal output from the current detection amplifier circuit 40 is 90% or more of a predetermined reference wave height, while 50% or less of the predetermined reference wave height. When it becomes, it is controlled to increase the gain. As a result, the gain of the differential amplifier circuit 36 is automatically switched to an optimum gain according to the large, medium, and small currents I flowing through the power line L1 as shown in FIG. It becomes possible to do.

  As shown in FIG. 8, the voltage detection amplifier circuit 50 includes a balanced amplifier 37 on the input side of the differential amplifier circuit 38, and includes an equalizer circuit 39 on the output side of the differential amplifier circuit 38. The differential amplifier circuit 38 has a configuration in which a negative feedback circuit having a resistor R7 is provided in the operational amplifier OP2, and a bias voltage (Vcc / 2) is applied to the plus input via the resistor R8.

  The balanced amplifier 37 is provided with a negative feedback circuit having a resistor R3 in each of the first and second operational amplifiers OP3 and OP4, and the negative inputs are connected to each other through the resistor R4. One voltage detection electrode 18 is connected to the plus input of OP3 via the core wire 19A of the shield cable 19, while the other voltage detection electrode 18 is connected to the plus input of the second operational amplifier OP4 via the core wire 19A of the shield cable 19. Connected. The output of the first operational amplifier OP3 is connected to the positive input of the operational amplifier OP2 of the differential amplifier circuit 38 via a resistor R6, while the output of the second operational amplifier OP4 is connected via a different resistor R6. This is connected to the negative input of the operational amplifier OP2 of the dynamic amplifier circuit 38. A voltage dividing circuit 41 is provided between the positive inputs of the first and second operational amplifiers OP3 and OP4 to divide the positive inputs into a one-to-one relationship by a pair of resistors R5 and R5. A one-to-one voltage dividing point of the voltage dividing circuit 41 is grounded to the ground member 94 via the capacitor C4, and a bias voltage (Vcc / 2) is applied to the voltage dividing point.

  The equalizer circuit 39 is an RC-type low-pass filter including a resistor R9 and a capacitor C5, and has higher harmonics than the primary frequency component (for example, 50 Hz or 60 [Hz]) included in the voltage of the power lines L1 and L2. Equalize ingredients. Specifically, the circuit between the power line L1 and the input of the operational amplifier OP3 includes a capacitor C7 and a voltage dividing circuit 41 that are formed by a capacitive component between the voltage detection electrode 18 and the shield electrode 14, as shown in FIG. Are connected in parallel between a power line L1 as an AC power supply and a ground, and a capacitor C6 due to a capacitance component between the voltage detection electrode 18 and the power line L1 is connected to a power line L1 and a capacitor C7 as an AC power supply. And a circuit connected in series with a common connection point with the resistor R5. The same applies to the circuit between the power line L2 and the input of the operational amplifier OP4. In addition, if the voltage frequency of the power lines L1 and L2 is a commercial power supply, for example, the primary frequency is 60 [Hz], the capacitor C7 can be considered non-conductive. In other words, as shown in FIG. 9B, the circuit on the input side of the voltage detection amplifier circuit 50 can be regarded as a CR type high-pass filter circuit 93 including a capacitor C6 and a resistor R5.

  By the way, when the voltage of the commercial power source is actually measured, the voltage waveform thereof may be, for example, a waveform closer to a triangular wave than a sine wave, as shown in FIG. The level of any one of the second, third, fourth,... Harmonic components increases (for example, in the actual measurement results, the levels of a plurality of harmonic components of the fifth or higher order increase). )

  However, as described above, the input side of the voltage detection amplifier circuit 50 is a CR-type high-pass filter circuit 93. Therefore, the harmonics of the high-pass filter circuit 93 are higher than the primary frequency component due to the frequency characteristics of the gain. The components are transmitted with each other gain. Specifically, when the power detection device 10 is prototyped, the capacitor C6 due to the capacitance component between the voltage detection electrode 18 and the power line L1 is 8.9 [pF], and the voltage detection electrode 18 and the shield electrode 14 are The capacitor C7 due to the capacitance component between them was 1.4 [pF]. Since the resistor R5 is set to 1 [MΩ], for example, the frequency characteristic of the gain of the high-pass filter circuit 93 is approximately +6 [dB / oct] as shown in FIG. Therefore, when the primary frequency is 60 [Hz], the second harmonic is approximately +6 [dB], the third harmonic is approximately +9 [dB], and the fourth harmonic is approximately +12 [dB]. Detection is performed by increasing the gain.

  Therefore, in the present embodiment, the equalizer circuit 39 that is an RC type low-pass filter is provided on the output side of the voltage detection amplifier circuit 50 in the present embodiment. The amount detected by increasing the gain for each frequency by the CR-type high-pass filter circuit 93 on the input side of the voltage detection amplifier circuit 50 can be canceled (corrected) by the equalizer circuit 39, and the detection accuracy can be improved. As described above, if the frequency characteristic of the high-pass filter circuit 93 is, for example, approximately +6 [dB], the frequency characteristic of the equalizer circuit 39 that is an RC low-pass filter is approximately −6 [dB / oct]. It is preferable that

  The microcomputer 96 shown in FIG. 1 acquires voltage detection data and current detection data from the voltage detection amplification circuit 50 and the current detection amplification circuit 40 through the A / D converter 95. The microcomputer 96 is formed by packaging a CPU, a ROM, and a RAM. In the ROM, a conversion constant for converting the voltage detection data acquired from the measurement terminal 11 into a voltage value between the power lines L1 and L2, and the measurement terminal 11 A conversion constant for converting the acquired current detection data into a current value flowing through the power line L1 using the gain value of the differential amplifier circuit 36, a program for calculating power using the conversion constant, and the like are stored. ing. Then, the microcomputer 96 calculates a power value from the voltage detection data and current detection data and the value of the variable gain, and wirelessly outputs it to the data processing terminal 12 using the transmission circuit 97. Note that the above-described conversion constant is set by performing calibration or the like, for example.

  As shown in FIG. 1, the data processing terminal 12 includes a receiving circuit 98 and a personal computer 99, and takes in a power value wirelessly transmitted from the measuring terminal 11 into the personal computer 99 through the receiving circuit 98. The receiving circuit 98 and the personal computer 99 receive power by connecting a plug to a commercial power outlet, for example.

  The personal computer 99 calculates, for example, the power value obtained from the measurement terminal 11 by, for example, time integration, sets the power value, the power amount, and their measurement time, time, etc. So that it is transmitted to the electric power company via the Internet. The power company determines, for example, whether or not to send a power saving alarm based on the power value and power amount data transmitted from the plurality of power detection devices 10 provided in the plurality of residences, and determines the power generation amount. Decide whether to increase.

  This completes the description of the configuration of the power detection device 10 of the present embodiment. In the power detection device 10, the personal computer 99 corresponds to a “voltage calculation circuit”, a “current calculation circuit”, and a “power calculation processing circuit”, and includes a voltage detection amplification circuit 50 having a differential amplification circuit 38 according to the present invention, The “voltage detection processing circuit” according to the present invention is configured from the personal computer 99 and the current detection amplification circuit 40 having the differential amplification circuit 36 as the “amplification circuit” according to the present invention is connected to the “current detection according to the present invention”. Processing circuit "is configured. The voltage detection amplification circuit 50 and the personal computer 99 constitute the “voltage detection processing circuit” according to the present invention, and the “voltage detection processing circuit” and the “first and second voltage detections” according to the present invention. A “voltage detection device” according to the present invention is constituted by a pair of voltage detection electrodes 18 and 18 corresponding to “electrodes” and a pair of shield electrodes 14 and 14. In other words, the power detection device 10 includes a “voltage detection device” according to the present invention.

  Hereinafter, the operational effects of the power detection device 10 of the present embodiment and the “voltage detection device” included therein will be described. In the power detection device 10 of the present embodiment, the voltage detection electrodes 18 and 18 that are electrostatically coupled to the power lines L1 and L2 for voltage detection are covered with the shield electrodes 14 and 14, so Noise is hardly added. Further, since the potential difference between the voltage detection electrodes 18 and 18 is differentially amplified by the differential amplifier circuit 38, the noise of the common-mode voltage of the voltage detection electrodes 18 and 18 is canceled at that time. Further, by providing the balanced amplifier 37 mainly composed of the operational amplifiers OP3 and OP4 on the input side of the differential amplifier circuit 38, the input of the “voltage detection processing circuit” becomes high impedance, thereby causing electrostatic coupling. The voltage detected by the voltage detection electrodes 18 and 18 having high impedance between the power lines L1 and L2 can be taken into the “voltage detection processing circuit” without being lowered. Moreover, since all the circuits included in the power detection device 10 are grounded to a common ground (ground member 94), when a plurality of circuits included in the power detection device 10 are grounded to a plurality of separate grounds. The influence on the detection result of the voltage due to the potential difference between the grounds can be suppressed. As a result, the power detection apparatus 10 can suppress the influence on the voltage detection result due to the environment around the voltage detection electrodes 18 and 18 and can detect the voltage more accurately than in the past, and the voltage detection result. It becomes possible to detect electric power and electric energy more accurately than before. In addition to these, since the wireless transmission is performed between the measurement terminal 11 and the data processing terminal 12 constituting the power detection device 10, the data processing terminal 12 is disconnected from the voltage detection electrodes 18 and 18, and the data The degree of freedom of the configuration of the processing terminal 12 is increased, and a general-purpose personal computer 99 can be used.

[Second Embodiment]
This embodiment is shown in FIG. 12, and only the configuration of the voltage sensor 13 is different from that of the first embodiment. In this voltage sensor 13W, instead of the voltage detection electrode 18 in the voltage sensor 13W of the first embodiment, a U-shaped groove-shaped voltage detection electrode 18W has a groove opening directed in a direction in which the metal casings 15 and 15 face each other. In this state, it is fixed to one metal casing 15 via an insulating support block 17.

[Third Embodiment]
This embodiment is shown in FIG. 13, and the voltage sensor 13V has a structure in which one shield electrode 14V is provided in common with the pair of voltage detection electrodes 18V and 18V. This is significantly different from the second embodiment. Specifically, the shield electrode 14V is composed of a pair of horizontally long metal casings 15V and 15V. Although not shown, the pair of metal casings 15V and 15V are provided with flanges (not shown) so that they can be overlapped with each other, and a pair of metal casings 15V and 15V is formed by screws and nuts that pass through the flanges. Are held in a combined state. Further, a total of four power line receiving recesses (not shown) having the same shape as the power line receiving recesses 15C (see FIG. 2) of the first embodiment are formed on the opening edge of each metal casing 15V, one by one. A total of four power line insertion holes (not shown) are formed in the shield electrode 14V in the combined state of the casings 15V and 15V.

  Further, the interiors of both metal casings 15V and 15V are filled with insulating support members 17V and 17V made of the same material as the insulating support block 17 of the first embodiment. A pair of U-shaped groove-shaped voltage detection electrodes 18V and 18V are fixed on the same axis of the pair of power line receiving recesses in one metal casing 15V. A pair of auxiliary metal fittings 18U and 18U having the same shape as the voltage detection electrode 18V are fixed on the same axis of the pair of power line receiving recesses of the other metal casing 15V. Furthermore, the core wires 19A and 19A of the shield cables 19 and 19 penetrating the one metal casing 15V are connected to the voltage detection electrodes 18V and 18V, and the shield wires 19B and 19B of the shield cables 19 and 19 are connected. When the metal casings 15V and 15V are combined with the voltage detection electrodes 18V and 18V of the one metal casing 15V in a state where the power lines L1 and L2 are arranged, the power lines L1 and L2 pass through the power line insertion holes and the shield electrode 14V. And the voltage detection electrode 18V and the auxiliary metal fitting 18U that are joined to each other are held in a state of penetrating each other.

  Thus, in the voltage sensor 13V of the present embodiment, since one shield electrode 14V is provided in common for the pair of voltage detection electrodes 18V and 18V, a compact configuration can be achieved. In addition, since the power lines L1 and L2 are inserted into and separated from the two pairs of power line insertion holes formed at the joint portion between the metal casings 15V and 15V, the voltage detection electrodes assigned to the power lines L1 and L2 The mutual influence between 18 and 18 can also be suppressed.

[Fourth Embodiment]
This embodiment is shown in FIG. 14, and is greatly different from the first and second embodiments in that the voltage sensor 13Y can be attached to the power lines L1, L2 in an integrated state. Specifically, the shield electrode 14Y of the voltage sensor 13Y includes, for example, a pair of metal housings 15Y and 15Y having a structure in which an elliptic cylinder with both ends is vertically divided into two. Although not shown, the pair of metal casings 15Y and 15Y includes flanges (not shown) that can be overlapped with each other, and a pair of metal casings 15Y and 15Y is formed by screws and nuts that pass through the flanges. Are held in a combined state.

  A groove-shaped insulating support member 17Y corresponding to each metal housing 15Y is fixed to the inner surface of each metal housing 15Y, and a U-shaped groove-shaped voltage detection electrode 18Y is provided on the bottom side of the groove of the insulating support member 17Y. Each is fixed. Further, each of the metal casings 15Y is provided so that an oval power line insertion hole (not shown) is provided in the center of the end walls at both ends in the axial direction of the shield electrode 14Y (direction orthogonal to the paper surface of FIG. 14). Power line receiving recesses (not shown) are formed at both ends in the axial direction.

  Then, when the metal casings 15Y and 15Y are combined in a state where one of the integrated power lines L1 and L2 is disposed in the voltage detection electrode 18Y of the one metal casing 15Y, as shown in FIG. Within the electrode 14Y, the voltage detection electrodes 18Y and 18Y are held in a state where they are respectively addressed to the power lines L1 and L2. That is, according to the configuration of the present embodiment, when a pair of power lines L1 and L2 are integrally fixed, the power lines L1 and L2 can be attached to the power detection device without being separated.

[Fifth Embodiment]
This embodiment is shown in FIG. 15, and the structure of the first clamper 20V for current detection is different from that of the first embodiment. That is, the first clamper 20V of the present embodiment includes a pair of C-shaped cores 21V and 21V that are supported so as to be able to approach and separate from each other with their C-shaped opening portions facing each other. Then, between the cores 21V and 21V, the cores 21V and 21V are brought close to each other in a state where a power cable in which a pair of power lines L1 and L2 are integrally fixed is disposed between the cores 21V and 21V. The power cable can be held in a state where the power lines L1 and L2 are arranged inside the portion. Further, the detection coils 22V and 22V are wound around the cores 21V and 21V, and a capacitor C8 is provided in a closed circuit in which both ends of the detection coils 22V and 22V are connected to each other. The voltage is taken into the current detection amplifier circuit 40. According to the configuration of the present embodiment, when the pair of power lines L1 and L2 are integrally fixed, the first clamper 20V for detecting a current can be attached without separating the power lines L1 and L2. Note that the structure of the first clamper 20V of the present embodiment may be applied to the second clamper 23 for receiving power of the first embodiment.

[Other Embodiments]
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various other than the following can be made without departing from the scope of the invention. It can be changed and implemented.

(1) In the power detection device 10 of the first embodiment, the microcomputer 96 of the measurement terminal 11 calculates the power value and wirelessly transmits the power value to the data processing terminal 12. Instead of calculating the power value, voltage data and current data may be transmitted to the data processing terminal 12 and the personal computer 99 on the data processing terminal 12 side may calculate the power value.

(2) The pair of metal housings 15 and 15 (15V, 15V, 15Y, and 15Y) of the first to fourth embodiments are fixed in a combined state by screws and nuts. One side edge of the metal casing is connected with a hinge, and a hook is provided on the other side edge of each of the metal casings, and the metal casings are combined with rubber wrapped around the both hooks. It may be fixed to. Moreover, you may connect the other one side edge part of a metal housing | casing by a buckle mechanism, and may fix it to a united state.

DESCRIPTION OF SYMBOLS 10 Electric power detection apparatus 11 Measuring terminal 12 Data processing terminal 13,13V, 13W, 13Y Voltage sensor 14,14V, 14Y Shield electrode 14A Power line insertion hole 15,15V, 15Y Metal housing 15C Power line acceptance recessed part 15D Shield electric wire insertion hole 16 Cushion Member 17 Insulation support block (insulation member)
17V, 17Y Insulation support member (insulation member)
18, 18V, 18W, 18Y Voltage detection electrode 19 Shielded cable 19A Core wire 19B Shielded wire 24 Core (saturable core)
25 receiving coil 30 power supply circuit 36 differential amplifier circuit 37 balanced amplifier 39 equalizer circuit 40 current detection amplifier circuit 50 voltage detection amplifier circuit 94 ground member 97 transmission circuit 98 reception circuit 99 PC C1 to C8 capacitor L1, L2 power line N neutral line OP1 ~ OP4 Operational Amplifier R1 ~ R9 Resistor

Claims (13)

A voltage detection device that detects a voltage between the first and second power lines that are 180 degrees out of phase in a single-phase two-wire or single-phase three-wire power line,
First and second voltage detection electrodes that can be electrostatically coupled to the first and second power lines via their insulating coatings;
A shield electrode covering the first and second voltage detection electrodes;
A differential amplifier circuit for amplifying a potential difference between the first and second voltage detection electrodes; and a voltage calculation circuit for calculating a voltage between the first and second power lines based on an output of the differential amplifier circuit. Including a voltage detection processing circuit,
A voltage detection apparatus comprising: a circuit portion connected to the first and second voltage detection electrodes in the voltage detection processing circuit; and the shield electrode grounded to a common ground. A balanced amplifier having first and second operational amplifiers is provided on the input side of the differential amplifier circuit, and the balanced amplifier connects the first voltage detection electrode to the positive input of the first operational amplifier and One input of the differential amplifier circuit is connected to the output of the first operational amplifier, the second voltage detection electrode is connected to the positive input of the second operational amplifier, and the output of the second operational amplifier is connected. The other input of the differential amplifier circuit is connected, and the negative inputs of the first and second operational amplifiers are connected via a resistor,
A voltage dividing circuit that divides the positive inputs of the first and second operational amplifiers in a one-to-one relationship is provided, and the voltage dividing point of the voltage dividing circuit is common to the shield electrode and the voltage detection processing circuit. The voltage detection apparatus according to claim 1, further comprising a bias circuit that biases the grounded ground so as to have a high potential.   An equalizer circuit for equalizing harmonics having a higher frequency than the first order wave included in the voltage wave applied to the first and second power lines is provided on the output side of the differential amplifier circuit. The voltage detection apparatus according to claim 1 or 2.   A transmission circuit and a reception circuit for transmitting and receiving an optical signal or a radio signal as an output of the differential amplifier circuit are provided between the differential amplifier circuit and the voltage calculation circuit in the voltage detection processing circuit, and the differential 4. The voltage detection device according to claim 1, wherein a non-conduction is made between the amplifier circuit and the voltage calculation circuit. 5.   5. The voltage detection device according to claim 4, further comprising: a power supply circuit that receives power by electromagnetic induction coupling to the first or second power line and supplies power from the transmission circuit to the differential amplifier circuit side.   A coil is wound around one or both of a pair of split cores obtained by splitting a ring-shaped saturable core into two parts, and an electromagnetic induction coupling portion capable of sandwiching the power line between the pair of split cores The voltage detection device according to claim 5, wherein the voltage detection device is provided in a power supply circuit. The shield electrode is provided separately for each of the first and second voltage detection electrodes, and each shield electrode is constituted by a pair of metal casings that are open on one side,
The united holding means for holding the edge of the opening of the pair of metal casings in a united state, the shield cable insertion hole formed in one of the metal casings, and the bonding between the metal casings A power line receiving recess that is formed in a portion and constitutes a power line insertion hole through which the first or second power line can be inserted;
Each of the first and second voltage detection electrodes is fixed to an inner surface of the metal casing via an insulating member and is directed to a side surface of the first or second power line inserted through the power line insertion hole. Placed in
The first and second voltage detection electrodes are connected to the differential amplifier circuit by a core wire of a shield cable inserted through each of the shielded electric wire insertion holes, and the first and second voltage detection electrodes are connected by the shield wire of the shield cable. The voltage detection apparatus according to claim 1, wherein a shield electrode is grounded to the ground common to the voltage detection processing circuit. The shield electrode is provided in common with the first and second voltage detection electrodes, and is composed of a pair of metal casings that are open on one side,
The united holding means for holding the edge of the opening of the pair of metal casings in a united state, the shield cable insertion hole formed in one of the metal casings, and the bonding between the metal casings A pair of power line insertion holes formed in a portion and capable of being inserted in a state in which the first and second power lines are separated,
Each of the first and second voltage detection electrodes is fixed to an inner surface of one of the pair of metal casings via an insulating member, and is inserted through the pair of power line insertion holes. Arranged to be addressed to the side surfaces of the first and second power lines,
The first and second voltage detection electrodes are connected to the differential amplifier circuit by a pair of shielded cable cores inserted into the shielded wire insertion hole, and the shield electrode is connected by the shielded wire of the pair of shielded cables. The voltage detection device according to claim 1, wherein the voltage detection device is grounded to the common ground with the voltage detection processing circuit.   The first and second voltage detection electrodes are formed in a U-shaped groove shape, and the two sides of the U-shape are arranged so as to face each other in the facing direction of the pair of metal casings. 9. The voltage detection device according to 8. The shield electrode is provided in common with the first and second voltage detection electrodes, and is composed of a pair of metal casings that are open on one side,
Combined holding means for holding the edges of the opening of the pair of metal housings joined together, a shield cable insertion hole formed in each of the metal housings, and a joint portion between the metal housings A pair that can be inserted through the first and second power lines together and can be held in a state in which the first and second power lines are arranged in the opposing direction of the pair of metal housings. With power line insertion hole.
The first and second voltage detection electrodes are divided into the pair of metal housings and fixed through insulating members, respectively, and are inserted into the pair of power line insertion holes. Two power lines are placed facing each other,
The first and second voltage detection electrodes are connected to the differential amplifier circuit by a core wire of a shield cable inserted into the shield wire insertion hole of each metal casing, and each metal is connected by a shield wire of the shield cable. The voltage detection apparatus according to claim 1, wherein a casing is grounded to the ground common to the voltage detection processing circuit.   A pair of insulating cushion members fixed to the pair of metal casings and sandwiching the first and second power lines in a combined state of the pair of metal casings are provided. Item 11. The voltage detection device according to any one of Items 7 to 10. A voltage detection device according to any one of claims 1 to 11,
A current detection coil that can be electromagnetically coupled to the first or second power line via their insulation coating;
A current detection processing circuit for calculating a current flowing in the first and second power lines based on an induced current flowing in the current detection coil;
A power detection processing circuit that calculates the power or the amount of power transmitted through the first and second power lines from the calculation result of the current detection processing circuit and the calculation result of the voltage detection processing circuit in the voltage detection device; With
A power detection apparatus comprising: a circuit portion that is electrically connected to the first and second voltage detection electrodes and the shield electrode of the current detection processing circuit and the power detection processing circuit and grounded to a common ground. The current detection processing circuit calculates an electric current flowing through the first and second power lines based on an amplification circuit that amplifies a voltage signal corresponding to the induced current flowing through the current detection coil, and an output of the amplification circuit. Current calculation circuit,
A transmission circuit and a reception circuit for transmitting and receiving an output of the amplification circuit as an optical signal or a radio signal are provided between the amplification circuit and the current calculation circuit in the current detection processing circuit, and the amplification circuit and the current calculation are provided. While not conducting between the circuit and
A transmission circuit and a reception circuit for transmitting and receiving an optical signal or a radio signal as an output of the differential amplifier circuit are provided between the differential amplifier circuit and the voltage calculation circuit in the voltage detection processing circuit, and the differential The power detection device according to claim 12, wherein a non-conduction is made between the amplifier circuit and the voltage calculation circuit.

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