JP2015172490A - Electricity measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electricity measuring device capable of simply and safely detecting terminal voltage of opening/closing means even in a hot line condition by reducing risks of short circuiting between phases and electric shock.SOLUTION: An electricity measuring device includes: magnet probes 1A, 1B that are attracted by magnetic force of a magnet and connected with one terminal of a breaker that is connected between a power supply side and a load side and that opens or closes a circuit between them; an electric-optical conversion unit 2 that converts an electric signal representing terminal voltage detected via the magnet probes 1A, 1B into an optical signal; optical fibers 3A, 3B that propagate the optical signal input from one end surfaces; an optical-electric conversion unit 5 that converts the optical signal output from the other end surfaces of the optical fibers 3A, 3B into an electric signal; and a measuring unit 5 that measures the terminal voltage on the basis of the electric signal obtained by the conversion.

Description

  The present invention relates to an electrical measuring device, and is particularly useful when applied to a load-side terminal of an opening / closing means such as a breaker to measure the voltage of a production facility such as a factory.

  In recent years, with increasing awareness of energy conservation, there is an increasing market need to reduce energy consumption by visualizing and centrally managing energy usage for each production facility in a factory. Breakers that have both power measurement and communication functions are already on the market, but they are expensive and require expert skills for installation. For this reason, there are many calls for a low-priced and easy-to-install product that is retrofitted to existing breakers. When measuring the power consumption of production equipment, it is necessary to detect the voltage on the load side (secondary side). In the case of such voltage measurement, conventionally, a connection clip for measuring voltage (a large alligator clip) is directly connected to a load-side terminal such as a breaker. Therefore, it is necessary to connect the lead wires for voltage measurement and the like in a live state. As a result, in such connection work, there is a risk that the measurement operator's hand touches the exposed metal portion to get an electric shock, and the clip may come off and short-circuit, resulting in a power failure.

  In addition, a lot of motors or the like that are sources of electromagnetic noise are installed in production facilities. For this reason, the number of wires extending from the terminals such as breakers to the measuring instrument is long and the number of wires is increased, and as a result of exposure to electromagnetic noise, noise and lightning surge voltage due to electromagnetic noise enter the measuring instrument, which only deteriorates the measurement accuracy. In some cases, it may cause a failure of the measuring instrument.

  Patent Document 1 is known as a voltage sensor for measuring a lightning surge using a light emitting diode or a photodiode.

JP 2004-219120 A

  By the way, since patent document 1 measures an ultra high voltage, it cannot be applied to the use of measuring the voltage of the load side of switching means, such as a breaker, safely in a live state. In short, at present, it is possible to detect the power of the production equipment at a low cost by measuring the voltage on the load side safely and with high accuracy in the live state of the open / close means such as a breaker and further combining it with the current information. A safe and simple voltage measuring device that can contribute to the construction of a system that can be used has not been proposed. Therefore, the appearance of such a voltage measuring device has been awaited.

  In view of the above-described prior art, the present invention eliminates the possibility of short-circuiting between phases and electric shock, makes it possible to detect the terminal voltage of the switching means safely and easily even in a live line state, and the power and power factor. An object of the present invention is to provide an electrical measuring device that can be used for detection and contribute to the development of an efficiency plan for energy use in factories and the like.

  The first aspect of the present invention that achieves the above object is that the first side of a switching means that is connected between the power supply side and the load side and opens and closes the circuit between them is attracted and connected by the magnetic force of the magnet. A magnetic probe, an electrical / optical converter that converts an electrical signal representing a terminal voltage detected via the magnet probe into an optical signal, an optical fiber that propagates the optical signal incident from one end surface, An optical / electrical converter that converts the optical signal emitted from the other end face of the optical fiber into an electrical signal, and a measuring unit that measures the terminal voltage based on the converted electrical signal, There is an electrical measuring device to do.

  According to this aspect, since the connection to the opening / closing means can be performed through the magnet probe, there is no fear of electric shock even in a live line state, and a predetermined connection operation can be easily performed with one touch. . Further, since a voltage signal is transmitted between the electrical / optical conversion unit and the optical / electrical conversion unit via an optical fiber, there is no influence of electromagnetic noise.

  According to a second aspect of the present invention, in the electric measuring device according to the first aspect, the circuit is a single-phase AC circuit, and the electric / optical conversion unit is connected in parallel in two opposite directions. -It has a light conversion element, and the said optical fiber is comprised by two so that each may transmit the optical signal which the said two said electricity / light conversion elements output, Furthermore, the said light / electricity conversion part is reverse direction In addition to having two optical / electrical conversion elements connected in parallel, the optical signals emitted from the optical fibers are converted into electrical signals, respectively, and the measuring unit is based on the two types of supplied electrical signals. The electrical measuring apparatus is for measuring the terminal voltage based on the peak-to-peak voltage on the plus side and the minus side of the single-phase circuit.

  According to this aspect, since it has two electrical / optical conversion elements and optical / electrical conversion elements connected in parallel in opposite directions, a voltage signal that reproduces all the waveforms of a single-phase alternating current satisfactorily is measured. Parts can be supplied. As a result, highly accurate voltage measurement is possible.

  According to a third aspect of the present invention, in the electrical measuring device according to the first aspect, the circuit is a three-phase AC circuit, and the optical / electrical converter is provided between a pair of terminals of the switching means. In addition to having two sets of two electric / optical conversion elements connected in parallel in opposite directions so as to measure the voltage of the optical fiber, the optical fiber transmits optical signals output by the two sets of electric / optical conversion elements, respectively. The optical / electrical converter converts the optical signals emitted from the optical fibers into electrical signals to generate two sets of electrical signals, and the measuring unit supplies The electrical measuring device is characterized in that the two sets of terminal voltages of the three-phase circuit are measured based on two types and two sets of electrical signals.

  According to this aspect, the two electrical / optical conversion elements and the optical / electrical conversion elements connected in parallel in the opposite direction form the electrical / optical conversion unit and the optical / electrical detection unit. A voltage signal in which the entire waveform of the voltage is well reproduced can be supplied to the measurement unit. As a result, highly accurate three-phase voltage measurement is possible.

  According to the fourth aspect of the present invention, in the electrical measuring device according to the third aspect, the magnet probe is arranged such that the probes of the phases at both ends maintain a predetermined distance from the probe of the center phase. The electrical measuring device is characterized by being restricted in position.

  According to this aspect, when measuring the voltage of the three-phase alternating current, it is possible to reliably connect the terminals in the proper phase order without making a mistake in the terminals of the switching means to be connected.

  According to a fifth aspect of the present invention, in the electrical measurement apparatus according to the fourth aspect, the probes of the phases at both ends are proximal to a pin formed to be movable on a center line passing through the center of the center phase. Are attached to the respective distal ends of the two levers that are pivotably attached, and are moved in a direction perpendicular to the center line while being regulated by the slide member, so that the relative position with respect to the center phase is The electrical measuring device is formed to be adjustable.

  According to this aspect, even if the dimension between the adjacent terminals of the opening / closing means changes, it is possible to flexibly cope with this and make a good predetermined connection.

  According to a sixth aspect of the present invention, in the electrical measurement device according to any one of the third to fifth aspects, a current flowing through the phases at both ends on the load side of the switching means is detected by the current detection means. An electric measuring device comprising the measuring unit configured to calculate the power supplied to the load side and / or the power factor based on the current detected by the current detecting means and the terminal voltage is there.

  According to this aspect, the power and power factor of the three-phase alternating current can be detected with high accuracy with a simple system.

  According to a seventh aspect of the present invention, in the electric measurement device according to any one of the first to sixth aspects, a plurality of types of current limiting, the resistance values of the electric wires extending from the terminal to the electric / optical conversion unit are different. An electrical measuring device is characterized in that a resistor is connected in parallel and any one of the current limiting resistors can be selected by a switch means.

  According to this aspect, by appropriately selecting the current limiting resistor according to the voltage of the terminal of the switching means to be measured, it is possible to perform a predetermined voltage measurement without changing the circuit configuration after the electrical / optical conversion unit. it can.

  According to the present invention, since it is connected to the terminal via the magnet probe, there is no worry of electric shock even when the opening and closing means is in a live state, and a predetermined connection operation can be safely performed with one touch. it can. The connection work does not require any special qualifications and can be easily performed by anyone. In addition, the voltage signal is transmitted between the electrical / optical converter and the optical / electrical converter via an optical fiber, so it is not affected by electromagnetic noise and requires no special detection circuit. Accurate voltage measurement is possible. Since no detection circuit is required, no separate power supply is required.

  That is, since the number of charged parts can be reduced as much as possible, safe voltage measurement is possible even in a live line state, and the cost is reduced.

1 is a circuit diagram showing an electrical measuring device according to a first embodiment of the present invention. It is a circuit diagram which shows the electrical measuring device which concerns on the 2nd Embodiment of this invention. It is a perspective view shown in the state where a connection jig provided with a magnet probe of an electric measuring device concerning a 2nd embodiment of the present invention was attached to a breaker which is an opening-and-closing means. 3A is a front view, FIG. 3B is a right side view of the probe portion cut out, and FIG. 3C is a cutaway view of the probe portion. It is a bottom view. FIG. 4 is a structural diagram showing a position adjusting mechanism that adjusts the interval between probes constituting each phase in the connecting jig shown in FIG. 3. It is a circuit diagram which shows the electric measuring device which can detect the electric power and power factor of three-phase alternating current which are the 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
FIG. 1 is a circuit diagram showing an electrical measuring apparatus according to the first embodiment of the present invention. As shown in the figure, the electrical measuring apparatus according to the present embodiment measures a single-phase AC inter-terminal voltage, and includes magnet probes 1A and 1B, an electrical / optical conversion unit 2, optical fibers 3A and 3B, optical / optical An electric conversion unit 4 and a measurement unit 5 are included.

  Here, the magnet probes 1A and 1B are attracted and connected to a load-side terminal of, for example, a breaker (not shown in FIG. 1), which is an open / close means on the power source side and the load side, by the magnetic force of the magnet. More specifically, the magnet probes 1A and 1B are obtained by fixing a permanent magnet inside a cylindrical member formed of an insulating material such as a resin, and a lead wire as a lead wire is pressed against the terminal by a magnetic force through the permanent magnet. By doing so, the electrical connection with the terminal is ensured. The electrical / optical converter 2 converts an electrical signal representing a terminal voltage detected via the magnet probes 1A and 1B into an optical signal. In this embodiment, two electrical / optical converters connected in parallel in opposite directions are used. It is composed of light conversion elements 2A and 2B. As a result, the electrical / optical conversion element 2A is lit by being supplied with a current during the positive half cycle of the single-phase AC voltage, and irradiates an optical signal representing a voltage corresponding to the positive half cycle. On the other hand, the electrical / optical conversion element 2B is lit by being supplied with a current during the negative half cycle of the single-phase AC voltage, and irradiates an optical signal representing a voltage corresponding to the negative half cycle. The optical signal irradiated by the electrical / optical conversion element 2A is transmitted to the optical / electrical conversion unit 4 via the optical fiber 3A, and the optical signal irradiated by the electrical / optical conversion element 2B is transmitted via the optical fiber 3B.

The optical / electrical converter 4 converts optical signals emitted from the optical fibers 3A and 3B into electrical signals, respectively. In this embodiment, two optical / electrical conversion elements 4A, 4B. As a result, an optical signal corresponding to the positive half-cycle voltage of the single-phase AC voltage is supplied to the photoelectric conversion element 4A and converted into an electrical signal, and a voltage signal representing the voltage corresponding to the positive half-cycle is converted into an electric signal. Send it out. On the other hand, the optical / electrical conversion element 4B is supplied with an optical signal corresponding to the negative half-cycle voltage of the single-phase AC voltage, is turned on and converted into an electrical signal, and represents a voltage signal representing the voltage corresponding to the negative half-cycle. Is sent out. The measurement unit 5 includes an operational amplifier 5A and a feedback resistor _Rf , and is supplied with voltage signals corresponding to the positive and negative of the single-phase alternating current converted by the optical / electrical conversion unit 4. As a result, the voltage value between the terminals of the breaker is detected via the output terminal Vout.

  In the present embodiment, a current limiting resistor R is connected on the way from the magnet probe 1A to the electrical / optical conversion unit 2, and the current supplied to the electrical / optical conversion elements 2A and 2B is less than the allowable current of the element. Restricted. Here, it is also possible to prepare a plurality of current limiting resistors R each having a different resistance value, connect them in parallel, and select one of them by switch means. As a result, the resistance value of the current limiting resistor R can be appropriately selected according to the terminal voltage to be measured, and a plurality of types of voltage measurements can be performed without changing the circuit configuration after the electrical / optical converter 2. it can. Such an effect can also be realized by making the current limiting resistor R a variable resistor.

  According to the present embodiment as described above, a predetermined voltage can be measured by one-touch mounting by simply attracting the magnet probes 1A and 1B to the load-side terminals of the breaker by magnetic force. At this time, even if the breaker is in a live state, not only can the connection work be performed without worrying about electric shock, but also the electrical / optical conversion unit 2 and the optical / electrical conversion unit 4 are connected by the optical fibers 3A and 3B. Therefore, the charged part is not exposed and is not affected by electromagnetic noise.

<Second Embodiment>
FIG. 2 is a circuit diagram showing an electrical measuring apparatus according to the second embodiment of the present invention. As shown in the figure, the electrical measuring device according to the present embodiment measures a voltage between terminals of a three-phase alternating current, and magnet probes (not shown in FIG. 2) corresponding to each phase of u, v, and w. ), Electrical / optical conversion units 12, 13, optical fibers 14A, 14B, 15A, 15B, optical / electrical conversion units 16, 17, and measurement units 18, 19. Here, the electrical / optical conversion unit 12 converts an electrical signal representing a terminal voltage between the u-phase and the v-phase detected via the magnet probe into an optical signal, and is connected in parallel in the reverse direction in this embodiment. It is composed of two electric / optical conversion elements 12A and 12B. As a result, the electrical / optical conversion element 12A is lit with a current supplied during the positive half cycle between the uv phases in the three-phase alternating current, and irradiates an optical signal representing a voltage corresponding to the positive half cycle. On the other hand, the electrical / optical conversion element 12B is lit by being supplied with a current during the negative half cycle of the uv phase in the three-phase alternating current, and irradiates an optical signal representing a voltage corresponding to the negative half cycle. Similarly, the electrical / optical converting unit 13 converts an electrical signal representing a terminal voltage between the w-phase and the v-phase detected via a magnet probe into an optical signal, and is connected in parallel in two opposite directions. The electrical / optical conversion elements 13A and 13B are used. As a result, the electrical / optical conversion element 13A is irradiated with an optical signal representing a voltage corresponding to the positive half cycle between the wv phases in the three-phase alternating current, and the electrical / optical conversion element 13B is the negative half of the wv phase in the three-phase alternating current. An optical signal representing a voltage corresponding to the period is irradiated.

  The optical signal irradiated by the electrical / optical conversion element 12A is transmitted to the optical / electrical conversion unit 16 via the optical fiber 14A, and the optical signal irradiated by the electrical / optical conversion element 12B is transmitted via the optical fiber 14B. Similarly, the optical signal irradiated by the electrical / optical conversion element 13A is transmitted to the optical / electrical conversion unit 17 via the optical fiber 15A, and the optical signal irradiated by the electrical / optical conversion element 13B is transmitted via the optical fiber 15B. The The optical / electrical converter 16 converts the optical signals emitted from the optical fibers 14A and 14B into electrical signals, respectively. In this embodiment, the two optical / electrical converters 16A, 16B. As a result, the optical signal corresponding to the positive half-cycle voltage of the uv terminal voltage is supplied to the photoelectric conversion element 16A and converted into an electrical signal, and a voltage signal representing the voltage corresponding to the positive half-cycle is obtained. Send it out. On the other hand, an optical signal corresponding to the negative half-cycle voltage of the uv terminal voltage is supplied to the photoelectric conversion element 16B, converted into an electrical signal, and a voltage signal representing the voltage corresponding to the negative half-cycle is sent out. To do. Similarly, the photoelectric conversion element 17A sends a voltage signal representing a voltage corresponding to the positive half cycle of the voltage between the wv terminals, while the photoelectric conversion element 17B corresponds to the negative half cycle of the voltage between the wv terminals. A voltage signal representing the voltage to be transmitted is transmitted.

The measurement unit 18 includes an operational amplifier 18A, a feedback resistor R _f1 , and a capacitor C1. Thus, the voltage signal representing the voltage between the uv terminals converted by the optical / electrical converter 16 is supplied to the measuring unit 18. As a result, the voltage value between the uv terminal is detected through a capacitor C3 and an output terminal Vout _1. On the other hand, the measurement unit 19 includes an operational amplifier 19A and a feedback resistor _Rf2 . Thus, the voltage signal representing the voltage between the wv terminals converted by the optical / electrical converter 17 is supplied to the measuring unit 19. As a result, the voltage value between wv terminal is detected through a capacitor C4 and the output terminal Vout _2.

In this embodiment, current limiting resistors R _UV and R _WV are connected on the way from the u-phase terminal to the electrical / optical converter 12 and on the way from the w-phase terminal to the electrical / optical converter 13. The current supplied to the light conversion elements 12A and 12B and the electric / light conversion elements 13A and 13B is limited to the allowable current of the elements or less. Here, it is also possible to prepare a plurality of current limiting resistors R _UV and R _WV each having a different resistance value, connect them in parallel, and select either one by the switch means. it can. As a result, the resistance values of the current limiting resistors R _UV and R _WV can be appropriately selected according to the terminal voltage to be measured, and a plurality of types can be obtained without changing the circuit configuration after the electrical / optical converters 12 and 13. Voltage measurements can be made. Such an effect can also be realized by making the current limiting resistors R _UV and R _WV variable.

  FIG. 3 is a perspective view showing a connection jig provided with a magnet probe according to the present embodiment in a state where the connection jig is mounted on a breaker as an opening / closing means. FIG. 4 is a three-view diagram showing the connection jig shown in FIG. FIG. 4B is a right side view showing the probe portion with a part cut away, and FIG. 4C is a bottom view showing the probe portion with a part cut away.

  As shown in these drawings, the breaker 21 serving as the opening / closing means in the present embodiment is a switch that electrically opens and closes between the power source side I and the load side II by rotating the lever 21A. A terminal block 21B is formed. Measurement terminal screw portions 22u, 22v, and 22w corresponding to respective phases of the three-phase AC uvw are screwed to the terminal block 21B. Conventionally, a lead wire for voltage measurement is connected to the measurement terminal screw portions 22u, 22v, 22w, or a predetermined three-phase AC voltage is generated by connecting a measuring device by biting an alligator clip. I was measuring.

  On the other hand, in this embodiment, a predetermined three-phase AC voltage is detected using the connection jig 20. More specifically, the connection jig 20 in this embodiment has three probes 23, 24, and 25 corresponding to the uvw phase and a casing 26 to which the base ends of the probes 23 to 25 are fixed. doing. Here, the probes 23 to 25 are fixed to the housing 26 so as to protrude downward. Each probe 23-25 has cylindrical members 23A, 24A, and 25A made of an insulating material having an opening at the tip, and the tip of each opening of the cylindrical members 23A to 25A is a measurement terminal screw portion. The connection jig 20 is attached to the breaker 21 by being inserted into 22u, 22v, and 22w.

  In this embodiment, of the three probes 23 to 25, only the center v-phase probe 24 is a magnet probe. That is, it has the magnet 24B fixed to the measurement terminal screw portion 22v by a magnetic force. The u-phase and w-phase probes 23 and 25 on both sides are springs 23C and 25C directed toward the opening portions of the cylindrical members 23A and 25A when the probe 24 is attracted to the measurement terminal screw portions 22u and 22w by the magnetic force. Due to the spring force, the iron pieces 23B and 25B at the front end are brought into contact with the measurement terminal screw portions 22u and 22w, thereby ensuring electrical connection. That is, in this embodiment, the connecting jig 20 is attached to the measurement terminal screw portions 22u, 22v, and 22w of the breaker 21 with one touch through the probes 23 to 25 by the strong magnetic force in the center v-phase probe 24. . Of course, all of the probes 23 to 25 may be constructed of magnet probes.

  In this embodiment, the electrical / optical conversion units 12 and 13 shown in FIG. Therefore, although not shown, the optical fibers 14A, 14B, 15A, and 15B are pulled out from the upper surface of the housing 26 and transmit optical signals toward the optical / electrical converters 16 and 17.

  In this embodiment, the interval between the adjacent probes 23, 24, 25 can be adjusted according to the interval between the measurement terminal screw portions 22u, 22v, 22w.

  FIG. 5 is a structural diagram showing a position adjusting mechanism for adjusting the interval between the probes constituting each phase in the connecting jig shown in FIG. The figure is a view of the inside of the housing 26 as seen from the front side. As shown in the figure, u-phase and w-phase probes 23 and 25 that are phases at both ends are attached to the tip portions of levers 27 and 28, respectively. The base end portions of the levers 27 and 28 are rotatably attached to the pin 29. The pin 29 is formed so as to be movable on a center line CL passing through the center of the v-phase probe 24 that is the center phase of the three-phase alternating current. Here, the pin 29 is formed so as to be movable in the vertical direction in FIG. On the other hand, the probes 23 and 25 are configured to move in a direction orthogonal to the center line CL while being restricted by the slide members 31A and 31B in the vertical direction in the figure.

  Thus, from the state where the distance between the probes 23 and 25 shown in FIG. 5A is minimized, the distance between the probes 23 and 25 shown in FIG. 5B is maximized in the direction perpendicular to the center line CL. The probes 23 and 25 are continuously moved by a certain amount to adjust the relative positions of the u-phase and w-phase probes 23 and 25 with respect to the central v-phase probe 24. Thereby, the phase interval of the uvw phase can be adjusted in accordance with the intervals of the measurement terminal screw portions 22u, 22v, 22w of the breaker 21.

  As long as the distance between the probes 23, 24, and 25 matches the distance between the measurement terminal screw portions 22u, 22v, and 22w, the position adjusting mechanism for the probes 23 and 25 as shown in FIG. By forming it so as to be adjustable as in this embodiment, even if the intervals between the measurement terminal screw portions 22u, 22v, and 22w change, it is possible to flexibly cope with this and to make a good predetermined connection. That is, it becomes a highly versatile connection jig that can be commonly applied to a plurality of types of opening / closing means. In addition, since the relative positional relationship between the probes 23, 24, and 25 in the uvw phase is defined, it is possible to prevent work mistakes such as attaching the probes 23 to 25 with wrong phases.

  In the present embodiment, by configuring the positions of the probes 23 and 25 to be adjustable, a highly versatile connection jig 20 that can be commonly applied to a plurality of types of breakers 21 can be provided. Is not necessarily required. Even in this case, if the relative positional relationship between the probes 23, 24, and 25 in the uvw phase is defined, it is possible to prevent an operation error such as attaching the probes 23 to 25 with the wrong phases.

  According to the present embodiment as described above, the connection jig 20 is simply connected to the measurement terminal screw portions 22u, 22v, and 22w, which are terminals on the load side of the breaker 21, via the probes 23, 24, and 25 by magnetic force. Predetermined voltage measurement becomes possible by mounting with one touch. At this time, even if the breaker 21 is in a live line state, not only can the connection work be performed without worrying about electric shock, but also the optical fiber 14A, between the electrical / optical conversion units 12, 13 and the optical / electrical conversion units 16, 17 can be connected. Since it is connected by 14B, 15A, 15B, the charged part is not exposed and is not affected by electromagnetic noise.

<Third Embodiment>
FIG. 6 is a circuit diagram showing an electrical measuring apparatus capable of detecting the power and power factor of the three-phase alternating current according to the third embodiment of the present invention. As shown in the figure, in this embodiment, an electric power calculation function is added to the electric measurement device used for the three-phase AC voltage measurement shown in FIGS. Therefore, the same parts as those in FIGS. 2 to 5 are denoted by the same reference numerals, and redundant description is omitted. As shown in FIG. 6, in the present embodiment, currents I1 and I2 flowing in the u phase and the w phase on the load side of the breaker 21 are detected by the current detectors CT1 and CT2. On the other hand, the voltage V1 between the uv phases and the voltage V2 between the wv phases are based on the optical signals supplied to the optical fibers 14A, 14B, 15A, and 15B via the connection jig 20, and the optical / electrical converters 16 and 17 and the measurement unit. 18 and 19 are detected. The arithmetic processing unit 32 calculates the power consumption and power factor on the load side by performing a predetermined calculation based on the voltages V1 and V2 and the currents I1 and I2. Specifically, the three-phase power P and the three-phase power factor cosφ are calculated by the following equations.

P = V1, I1, cos φ1 + V2, I2, cos φ2
cosφ = P / √3 · V · I

  According to this embodiment, the power and power factor of the three-phase alternating current can be detected with high accuracy by simply adding predetermined current information.

<Other embodiments>
In the above-described embodiment, the electrical / optical conversion elements 2A, 2B, 12A, 12B, connected in reverse parallel
13A and 13B are used to detect not only current in one direction but also voltage information based on current in the reverse direction, so that each is converted into an optical signal and transmitted through optical fibers 3A, 3B, 14A, 14B, 15A, and 15B. However, it is not limited to this. In principle, the same object can be achieved by detecting either the positive side voltage or the negative side voltage. What is necessary is just to double the voltage based on a half wave. However, since it becomes a half wave, the measurement accuracy decreases. Instead, the number of optical fibers 3A, 3B, 14A, 14B, 15A, and 15B is halved, and the cost can be reduced.

Moreover, although the electric power and power factor in the said embodiment were demonstrated regarding the three-phase alternating current power, if the voltage information detected in the said 1st embodiment and current information are combined, the electric power and power factor of a single phase alternating current will be obtained. There is no doubt that it can be detected. That is, based on the voltage (V) obtained via the output terminal Vout of FIG. 1 and the current (I) obtained as current information of the single-phase load circuit (not shown), the single-phase power P ₀ and the single-phase power P The power factor cosφ may be calculated.

P ₀ = V · I · cosφ
cosφ = P ₀ / V · I

  The present invention is useful in an industrial field where maintenance and management of electrical equipment is performed based on power information or the like in a factory or the like.

I Power supply side
II Load side 1A, 1B Magnet probe 2, 12, 13 Electrical / optical converter 3A, 3B, 14A, 14B, 15A, 15B Optical fiber 4, 16, 17 Optical / electrical converter 5, 18, 19 Measuring unit 20 Connection Jig 21 Breaker 23, 24, 25 Probe

Claims (7)

A magnet probe connected between a power source side and a load side and attracted and connected to a terminal on one side of an opening / closing means for opening and closing a circuit between the two;
An electrical / optical converter that converts an electrical signal representing a terminal voltage detected via the magnet probe into an optical signal;
An optical fiber for propagating the optical signal incident from one end face;
An optical / electrical converter that converts the optical signal emitted from the other end face of the optical fiber into an electrical signal;
An electrical measurement apparatus comprising: a measurement unit that measures the terminal voltage based on the converted electrical signal. In the electric measuring device according to claim 1,
The circuit is a single-phase AC circuit;
The electrical / optical conversion unit has two electrical / optical conversion elements connected in parallel in opposite directions,
The optical fiber is composed of two optical signals that respectively transmit optical signals output by the two electric / optical conversion elements,
Furthermore, the optical / electrical conversion unit has two optical / electrical conversion elements connected in parallel in opposite directions, and converts the optical signals emitted from the optical fibers into electrical signals,
The measurement unit is configured to measure the terminal voltage based on a plus-side and minus-side peak-to-peak voltage of the single-phase circuit based on two types of supplied electric signals. In the electric measuring device according to claim 1,
The circuit is a three-phase AC circuit;
The light / electricity conversion unit has two sets of two electric / light conversion elements connected in parallel in opposite directions so as to measure a voltage between a pair of terminals of the opening / closing means,
The optical fiber is composed of four wires for transmitting optical signals output by the two sets of the electric / optical conversion elements,
The optical / electrical converter converts optical signals emitted from the optical fibers into electrical signals to generate two sets of electrical signals,
The measurement unit is configured to measure the two sets of terminal voltages of the three-phase circuit based on two types and two sets of supplied electrical signals. In the electric measuring device according to claim 3,
The magnetic measuring device is characterized in that the position of the phase probes at both ends is regulated so as to maintain a predetermined distance from the center phase probe. In the electric measuring device according to claim 4,
The phase probes at both ends are attached to the respective tip portions of two levers whose base end portions are rotatably attached to pins formed to be movable on a center line passing through the center of the center phase. In addition, the electrical measuring device is formed so that the relative position with respect to the central phase can be adjusted by moving in a direction orthogonal to the center line while the position is regulated by the slide member. In the electric measuring device according to any one of claims 3 to 5,
Electric current supplied to the load side based on the current detected by the current detection means and the terminal voltage is detected by the current detection means on the load side of the switching means, and / or its power factor. An electric measuring device, wherein the measuring unit is configured to calculate In the electric measuring device according to any one of claims 1 to 6,
A plurality of types of current limiting resistors having different resistance values are connected in parallel to the electric wire extending from the terminal to the electrical / optical conversion unit, and any one of the current limiting resistors can be selected by a switch means. An electrical measuring device characterized by.