WO2013030655A4 - Electricity meter - Google Patents

Electricity meter Download PDF

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Publication number
WO2013030655A4
WO2013030655A4 PCT/IB2012/001668 IB2012001668W WO2013030655A4 WO 2013030655 A4 WO2013030655 A4 WO 2013030655A4 IB 2012001668 W IB2012001668 W IB 2012001668W WO 2013030655 A4 WO2013030655 A4 WO 2013030655A4
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WO
WIPO (PCT)
Prior art keywords
current
detection unit
power
circuit
types
Prior art date
Application number
PCT/IB2012/001668
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French (fr)
Japanese (ja)
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WO2013030655A1 (en
Inventor
明実 塩川
雄介 宮村
省互 一村
西川　誠
裕 荻野
Original Assignee
パナソニック株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by パナソニック株式会社 filed Critical パナソニック株式会社
Priority to CN201280040798.1A priority Critical patent/CN103748475A/en
Publication of WO2013030655A1 publication Critical patent/WO2013030655A1/en
Publication of WO2013030655A4 publication Critical patent/WO2013030655A4/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R21/00—Arrangements for measuring electric power or power factor
    • G01R21/133—Arrangements for measuring electric power or power factor by using digital technique
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers

Definitions

  • the present invention relates to a power meter connected to a current transformer (CT) to measure the power of a circuit in a distribution board or the like.
  • CT current transformer
  • a current transformer is used to expand the measurement range.
  • a power measuring device is connected to the receiving side circuit of this current transformer, and the power measuring device inserts a burden resistance into the circuit connected to the current transformer, and detects the voltage across the burden resistance.
  • the current value can be measured to perform power calculation.
  • an alternating current of 100 A to several hundreds A is supplied, and a current transformer called pair 5A (hereinafter referred to as a pair 5 ACT) is used which can obtain 5 A of output current when the rated current is applied.
  • the pair 5 ACT is a so-called standardized output method when performing current measurement of a distribution system, and by combining it with a connectable power measuring instrument, a flexible power measuring system can be configured.
  • a branch circuit which is the terminal circuit in the distributed board.
  • a current of about several tens of Amps flows, for example, because the current from the main circuit is shunted.
  • a small-sized current transformer (hereinafter referred to as a small CT) having an output current of about several mA is used. Since the output current of this small CT is about 1/1000 of that of the pair 5 ACT, the core and winding of the core can be miniaturized. Therefore, the small CT can be used at a place where the pair 5 ACT can not be used due to the restriction of the shape, for example, for current measurement such as a branch circuit with a relatively low current in the distribution board. Thus, different types of current transformers need to be used properly depending on the installation space in the distribution board. Next, the load resistance connected to the current transformer and provided to the power measuring instrument will be described with reference to FIG.
  • the burden resistance 154 provided in the current detection unit 153 of the power measuring instrument 152 which is the receiving side circuit has a resistance value of several ⁇ .
  • the current detection unit 153 measures the current value by detecting the voltage at both ends of the burden resistor 154, and outputs the current value to the power calculation unit 155.
  • the output current is 5 A at maximum in the pair 5 ACT 156, it is connected to the shunt resistor 157 of several m ⁇ , and the current detection unit 153 detects the voltage across the shunt resistor 157 The current value is measured and output to the power calculation unit 155.
  • Unexamined-Japanese-Patent No. 7-229927 gazette
  • the resistance value of the burden resistance of the connected circuit is different. Specifically, as shown in FIG. 15, there is a difference of about 1000 times in the magnitude of the output current between the small CT 151 and the pair 5 ACT 156, and the burden resistance connected to the pair 5 ACT 156 is several m ⁇ , Load resistance is several ⁇ . Therefore, in order to measure the power of the circuit using different types of current transformers, separate measurement circuit units in which the input terminals are divided according to the magnitude of each output current according to the type of current transformers, Or, there is a problem that separate power measuring devices are required, which is costly.
  • Patent Document 1 discloses a current transformer that is easy to assemble, has a small mounting required area, has a high measurement accuracy, and can be easily adapted even if the magnitude of the detected current is different.
  • one type of current transformer is used to realize current measurement with different sizes by switching resistors, and power is measured using different types of current transformers. It is not a thing.
  • the present invention has been made in view of the above problems, and it is possible to connect any one of a plurality of current transformers with different outputs to the current detection unit without the need to perform circuit switching in the power measuring instrument. , And a power measuring device capable of measuring the power of a circuit in a distribution board or the like.
  • a voltage detection unit that detects a voltage signal from a circuit
  • a current detection unit that detects a current signal based on an output from a current transformer attached to the circuit
  • the voltage In a power measuring device including a detection unit and a power calculation unit that calculates power based on a current signal and a voltage signal detected by the current detection unit, the current detection unit includes at least two types of burden resistances, and And a signal processing circuit for processing the output from the flow device.
  • the current detection unit provides a power measuring device to which at least two or more different current transformers having different outputs can be connected.
  • the two types of load resistances provided in the current detection unit are connected in series, and the current transformers with different outputs of the two types are at predetermined positions of the load resistances connected in series according to their types, or the predetermined positions Preferably, it is connected to another predetermined position different from Two types of load resistances provided in the current detection unit are connected in series, and a relay for conduction is connected in parallel to at least one of the load resistances connected in series, and the current transformer Is preferably connected to the extreme ends of the series connected load resistors.
  • the current detection unit is a common connection terminal connected to one end of the series-connected load resistor and connected to a signal line serving as a reference of the outputs of the two different types of outputs of the current transformers;
  • the individual connection terminal connected to the position and the another predetermined position and to which the other signal line of the current transformer different in the two types of outputs is connected, and the signal connected from the individual connection terminal to the power calculation unit
  • the multiplexer further comprises a multiplexer having a circuit switching function for selecting a path of a line.
  • the two or more types of load resistances provided in the current detection unit are connected in series, and the load resistances connected in series are not shared by the different types of current transformers, and each type of current transformer is used.
  • connection terminals are provided individually.
  • the connection terminals provided at both ends of the load resistance having the largest resistance value have a structure that can not be connected except for dedicated connector terminals.
  • the circuit includes a main circuit and a plurality of branch circuits branched from the main circuit, and the current detection unit further includes a plurality of connection terminals connected to signal lines of different current transformers of at least two or more types of outputs. It is preferable that the plurality of connection terminals be disposed adjacent to each other for each of the circuits.
  • the plurality of connection terminals include a screw terminal connected to a signal line of the current transformer with a large output, and a connector terminal connected to a signal line of the current transformer of a small output, and the signal line of the current transformer
  • the connected plug has a structure that closes the other connection terminal when the connection with one of the screw terminal and the connector terminal is performed.
  • the signal line on the reference potential side which is connected in series with two or more types of load resistances provided in the current detection unit, is connected to the load resistance connected in series to a predetermined reference potential other than 0 V which is ground. It is preferable to connect.
  • the power meter is capable of multi-circuit power measurement.
  • the current detection unit includes a current detector for at least two types of load resistor is connected, the current transformer, depending on the type, a predetermined position of the load resistance, or the It may be connected to another predetermined position different from the predetermined position. Therefore, different types of current transformers can be connected to the same power meter, and the power of the circuit in the distribution board or the like can be measured.
  • FIG. 13 is a circuit diagram of a current detection unit provided in the power measuring instrument according to the first modification of the first embodiment.
  • FIG. 16 is a circuit diagram of a current detection unit provided in the power measuring instrument according to the second modification of the first embodiment.
  • FIG. 16 is a circuit diagram of a current detection unit provided in the power measuring instrument according to the third modification of the first embodiment.
  • FIG. 16 is a circuit diagram of a current detection unit provided in the power measuring instrument according to the fourth modification of the first embodiment. It is a circuit diagram of the current detection part with which the electric power measurement instrument concerning Embodiment 2 of this invention is equipped. It is a circuit diagram of an electric current detection part with which a power measuring instrument concerning Embodiment 3 of the present invention is equipped.
  • FIG. 21 is a circuit diagram of a current detection unit provided in the power measuring instrument according to the first modification of the third embodiment.
  • FIG. 21 is a circuit diagram of a current detection unit provided in the power measuring instrument according to the second modification of the third embodiment.
  • A The front view of the electric power measurement instrument which concerns on Embodiment 4 of this invention, (b) The bottom view of the electric power measurement instrument, (c) It is a top view of the electric power measurement instrument.
  • A A side view of the plug of the current transformer connected to the power measuring instrument according to the first modification of the fourth embodiment, (b) a perspective view of the same plug, (c) another side view of the same plug is there.
  • A The front view of the electric power measurement instrument which concerns on the modification 2 of the said Embodiment 4, (b) The bottom view of the electric power measurement instrument, (c) It is a top view of the electric power measurement instrument.
  • A A circuit diagram of a current detection unit in a conventional power meter, (b) A circuit diagram of a current detection unit in another conventional power meter.
  • the power measurement system S includes a distribution board 1, different types of current transformers 2 a and 2 b, a power measurement device 3, a monitoring device 4, a load 5, and breakers 6 a, 6 b and 6 c.
  • the power measurement system S monitors the power consumption of various loads 5 such as lighting fixtures and personal computers that receive power supply from the distribution board 1 in, for example, an office building or a general house.
  • loads 5 such as lighting fixtures and personal computers that receive power supply from the distribution board 1 in, for example, an office building or a general house.
  • Distribution board 1 shows a configuration for power measurement from an electric wire or the like using a three-phase three-wire system, for example, attaching current transformers 2a and 2b to the R / T phase and measuring a current value Is shown.
  • Distribution board 1 receives a commercial power supply externally supplied to the interior of a building or a house on the primary side via wire 7, and a plurality of power supply paths interposed between the secondary side of the main circuit and the main circuit. And a branch circuit.
  • loads 5 such as air conditioners and IH (Induction Heating) devices are connected to each branch circuit.
  • the breaker 6a is a main breaker connected to the electric wire 7 of the main circuit
  • the breaker 6b is a branch breaker disposed in a plurality of branch circuits branched from the main circuit.
  • the different types of current transformers 2a and 2b reduce the current of each circuit at a constant rate and supply the power measuring instrument 3 via the signal line 8 which is a dedicated cable.
  • the current transformer 2a is a 400/5 A penetration type
  • the number of turns of the coil is configured so that 5 A flows in the signal line 8 on the output side when a current of 400 A flows in the electric wire 7 penetrating the central portion. ing.
  • the current transformer 2a is installed to periodically measure the main current flowing in the main circuit through which a relatively large current flows, and in the figure, each of the wires of the main circuit is penetrated to measure the power And the signal line 8.
  • the current transformer 2b is installed to periodically measure the branch current flowing in each branch circuit through which a relatively small current flows, and is penetrated to a predetermined position of the electric wire of the branch circuit. It is connected by the signal line 8.
  • the current transformers 2a and 2b can be easily attached to the electric wire 7 of the main circuit and the branch circuit in a split type or the like, and erroneous connection can be prevented by using a dedicated cable as the signal line 8.
  • the power measuring device 3 is connected to the current transformers 2a and 2b, has a load resistance to be inserted in the circuit connected to the current transformers 2a and 2b, and the power of the circuit in which the current transformers 2a and 2b are installed is measure.
  • the power measuring device 3 outputs the calculation result to the monitoring device 4 via the communication line.
  • the power measuring instrument 3 has a size of, for example, 10 ⁇ 10 cm, and is installed at a predetermined position in the distribution board 1.
  • the monitoring device 4 is a dedicated personal computer or the like having a monitor, and is a monitoring unit that manages and displays energization information of each branch circuit.
  • the monitoring device 4 is network-connected to the power measuring instrument 3 via RS-485 communication or the like, performs data collection on the power use of each load 5, and displays a graph or the like for data analysis.
  • the monitoring device 4 automatically records, for example, data on power usage on an hourly or daily basis, performs batch management of energy via a network connected to the power measuring instrument 3, and “sees” efficient power usage
  • the load 5 is various electrical devices such as an air conditioner and an IH device as well as a lighting fixture and a personal computer connected to the branch circuit.
  • FIG. 2 shows a configuration for power measurement of one current transformer 2a or current transformer 2b for convenience.
  • the power measuring device 3 detects the current signal from the signals of the current transformers 2a and 2b, the voltage detection unit 32 detects the voltage signal of the circuit, and the current and voltage detection unit 32 in the current detection unit 31.
  • a power calculator 33 is provided to calculate power based on each signal of voltage.
  • the current detection unit 31 has a load resistance 311 inserted in a circuit connected to the current transformers 2a and 2b, a filter 312 for passing a signal of a predetermined frequency band, and a voltage value of a current signal passed through the filter 312.
  • an adder circuit 313 for adding The voltage detection unit 32 is connected to the electric wire 7 at a terminal via the breaker 6 c shown in FIG.
  • the power calculation unit 33 supplies the load 5 connected to the wire 7 to which the current transformers 2a and 2b are attached, based on the current measured by the current detection unit 31 and the voltage detected by the voltage detection unit 32. Is a microcomputer that calculates the power consumption.
  • the power calculation unit 33 includes A / D conversion units 331 and 332, a multiplication unit 333, and a transmission circuit unit 334.
  • the A / D conversion unit 331 converts an analog signal received from the voltage detection unit 32 into a digital signal.
  • the A / D conversion unit 332 converts an analog signal received from the current detection unit 31 into a digital signal.
  • the multiplication unit 333 is a circuit that multiplies the signals output from the A / D conversion units 331 and 332, that is, calculates the power.
  • the transmission circuit unit 334 has, for example, a two-wire serial communication circuit conforming to RS 485 or the like, and transmits the calculated power value to the monitoring device 4 capable of mutual communication via the connected communication line.
  • the current detection unit 31 includes two types of burden resistors 311 a and 311 b connected in series and different in resistance value.
  • the burden resistance 311 a is a 2.0 ⁇ resistance
  • the burden resistance 311 b is a 1 m ⁇ shunt resistance.
  • the shunt resistor is a high-precision resistor with a small resistance value made for current measurement of a circuit through which a large current flows.
  • the current detection unit 31 includes two types of load resistances that can be connected to two types of current transformers 2a and 2b, three types of current collectors that can be connected to three or more types of different current transformers The above burden resistance may be provided.
  • the signal line on the reference potential side connected to the burden resistors 311 a and 311 b is connected to the ground (GND) 314 at 0 V, and one end of the burden resistor 311 a is connected to the adding circuit 313 side.
  • the current detection unit 31 has a signal processing circuit that measures the voltage at the both ends of the load resistors 311 a and 311 b inserted in the circuit to obtain the current value.
  • the power measuring device 3 includes connection terminals 3a to 3c connected to the end portions of the load resistors 311a and 311b, respectively.
  • the current transformers 2a and 2b are different in the two types of outputs, and these current transformers 2a and 2b are, depending on the type, the extreme ends of the load resistors 311a and 311b connected in series, Alternatively, it is connected to a predetermined position between one end of the load resistors 311a and 311b connected in series and the load resistors 311a and 311b. That is, the signal line from the pair 5 ACT 2 a that outputs a relatively large current is connected to the connection terminals 3 b and 3 c because it is necessary to reduce the burden resistance inserted in the circuit.
  • connection terminal 3c is a common terminal for connecting the signal line serving as the reference of the outputs of the current transformers 2a and 2b
  • connection terminal 3a is an individual terminal for connecting the other signal lines of the current transformer 2b
  • the connection terminal 3b is an individual terminal for connecting another signal line of the current transformer 2a.
  • the connection positions of the signal lines of the different types of current transformers 2a and 2b are determined according to the resistance value of the burden resistors 311a and 311b connected in series.
  • the adjustment can be performed by changing the connection terminals 3a to 3c provided.
  • the power measuring device 3 it is possible to connect current transformers 2a and 2b having different outputs to the same current detection unit 31 without the need to perform circuit switching, and the power of the circuit in the distribution board 1 can be obtained. Measurement can be performed, and downsizing and cost reduction of the current measuring device 3 can be realized.
  • the monitoring device 4 communicatively connected to the power measuring instrument 3 makes it possible to “visualize” the power consumption of the load 5 so that it is possible to visually understand which load 5 should be reduced in power, etc. Energy saving can be realized.
  • the order which connects several burden resistance 311a, 311b in series makes the resistance value of the burden resistance 311b at the side of the reference electric potential 314 low. Thereby, the voltage drop can be suppressed to a low level with respect to the reference potential 314, the circuit of the power measuring instrument 3 can operate stably, and the influence of noise and the like can be reduced.
  • the relay 315 for conduction is connected in parallel to the burden resistor 311a.
  • the connection terminals 3a and 3c are respectively connected to the extreme ends of the load resistors 311a and 311b connected in series, and the current transformers 2a and 2b different in output are connected to the same connection terminals 3a and 3c.
  • the burden resistance 311a having a large resistance value is disposed on the reference potential 314 side among the burden resistances 311a and 311b connected in series.
  • the relay 315 When the pair 5ACT 2a is connected to the connection terminals 3a and 3c, the relay 315 is manually controlled by, for example, the switch unit 11 (see FIG. 12) described later, and the output current from the pair 5ACT 2a is shunt resistor 311b. It becomes a circuit that only passes through.
  • the relay 315 when the small CT 2b is connected to the connection terminals 3a and 3c, the relay 315 is manually controlled in the open state, and the output current from the small CT 2b passes through the shunt resistor 311b and the burden resistor 311a.
  • a second modified example of the first embodiment will be described with reference to FIG.
  • the second modified example of the first embodiment is similar to the first embodiment, but differs in that, for example, a manually controlled multiplexer 316 is added to both ends of the burden resistor 311a.
  • the current detection unit 31 is connected to a predetermined position (that is, both ends of the load resistance 311a) of the end of the two types of load resistances 311a and 311b connected in series, and power is supplied from the connection terminals 3a to 3c.
  • the circuit further includes a multiplexer 316 having a circuit switching function of selecting a path of a signal line connected to the arithmetic unit 33.
  • the signal switching multiplexer 316 is used as the circuit switching device, and current transformers 2a and 2b having different outputs can be connected to the same current detection unit 31 so that power distribution can be performed. It can measure the power of the circuit in the board.
  • the current detection unit 31 further includes a programmable gain amplifier 317 capable of changing the amplification factor of the signal.
  • the programmable gain amplifier 317 is an amplification circuit that can set the amplification factor from the outside using an analog switch or the like.
  • the outputs of the current transformers 2a and 2b differ depending on the rated current, but in the power measuring instrument 3 according to the third modification, gain switching is performed using the programmable gain amplifier 317, and a signal is input to the adding circuit 313 with an optimal signal.
  • the power calculation unit 33 can calculate the power.
  • the 4th modification A fourth modified example of the first embodiment will be described with reference to FIG.
  • the signal line on the reference potential side connected to the load resistors 311a and 311b is connected to a predetermined reference potential Vref other than 0 V which is the ground.
  • Vref a predetermined reference potential
  • the reference potential Vref can be applied, and the configuration of the addition circuit 313 for the signal obtained by the burden resistors 311a and 311b becomes unnecessary.
  • And can be connected to the AD conversion unit 332 of the power calculation unit 33.
  • Second Embodiment A power measuring instrument according to a second embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and the detailed description thereof is omitted (the same applies to the following).
  • the current detection unit 31 is connected to two load resistors 311a and 311b connected in parallel to one end of the current detector 31 and the other end of the load resistors 311a and 311b, and the current detection unit 31 outputs the current transformers 2a and 2b.
  • a circuit switching device (a contact relay with a low contact resistance with a 1c contact configuration) 318 having a circuit configuration in which the current path is one of the load resistors 311a and 311b, and an adder circuit 313 are provided.
  • the signal lines of the current transformers 2a and 2b are connected to the connection terminals 3a and 3c connected to both ends of the load resistors 311a and 311b connected in parallel regardless of the type.
  • the circuit switch 318 appropriately applies load resistance according to the type of the current transformers 2a and 2b. It can be connected to 311a and 311b. Therefore, the signal level of the current detection signal is raised to a predetermined level to improve the S / N ratio, thereby enabling accurate measurement of power.
  • the connection terminals 3b and 3d provided between the load resistors 311a and 311b connected in series in the current detection unit 31 are not shared by different types of current transformers 2a and 2b, but each type Provided separately.
  • connection terminals 3a and 3d are connected to the signal line of the small CT 2b, and the connection terminals 3b and 3c are connected to the signal line of the pair 5ACT 2a.
  • current transformers 2a and 2b having different outputs can be connected to the same current detection unit 31, power of circuits in the distribution board can be measured, and a current flow path from current transformers 2a and 2b Can be completely separated, allowing more accurate power measurement.
  • connection terminals 3a and 3d connected to both ends of load resistance 311a having a larger resistance value can not be connected except for dedicated connector terminals (plugs) 9a, that is, they fit with the shape of connector terminals 9a. It becomes connector shape 3e.
  • the pair 5 ACT 2 a is connected to the burden resistance 311 a having a large resistance value, and the burden resistance 311 a can be burnt out to prevent an accident due to a misconnection in advance.
  • the workability between the current transformers 2a and 2b and the power measuring device 3 can be improved by adopting the structure of the connector terminal 9a.
  • the connector terminal (plug) 9 b has a structure to which signal lines from two or more current transformers (two small CTs 2 b in this figure) can be connected.
  • a connector connection terminal 3f having a shape fitted to the connector terminal 9b is formed on the side surface etc. of the power measuring instrument 3.
  • FIG. 12 (a) is a front view of the power measuring instrument according to Embodiment 4 of the present invention
  • FIG. 12 (b) is a bottom view of the same power measuring instrument
  • FIG. 12 (c) is a top view of the same power measuring instrument. is there.
  • the power measuring instrument 3 according to the fourth embodiment includes a display unit 10, a switch unit 11, a voltage input terminal 12, a communication terminal 13, a pair 5 ACT connection terminal 14, and a small CT connection terminal 15.
  • the display unit 10 is a liquid crystal panel or the like that displays the power measurement result in each circuit.
  • the switch unit 11 is an operation key for setting the type of the current transformers 2 a and 2 b and setting the display of the display unit 10.
  • the voltage input terminal 12 is an input terminal connected to the electric wire for detecting a correlation voltage between the voltage pole S and the voltage pole T and the like.
  • the communication terminal 13 is a screw terminal connected to the monitoring device 4 and connecting a communication line used in RS-485 communication or the like.
  • the pair 5 ACT connection terminal 14 is a screw terminal for connecting the signal line from the pair 5 ACT 2 a.
  • the small CT connection terminal 15 is a connector terminal serving as an insertion port into which the connector terminal 9a from the small CT 2b is inserted.
  • a main trunk circuit and a circuit composed of a plurality of branch circuits branched from the main trunk circuit are disposed adjacent to each other in the lateral direction on the side surface of the power measuring instrument 3.
  • connection terminals 14 and 15 are arranged linearly in the front-rear direction.
  • simultaneous connection of a plurality of current transformers 2a and 2b to the same circuit can be visually prevented.
  • the above-described connection terminal is described as being disposed on the side surface of the power measuring instrument 3.
  • the connection terminal may be disposed on the upper surface, the lower surface, or the front.
  • the power measuring instrument 3 connects a plurality of connection terminals 14 which are screw terminals for connecting signal lines of a large output current transformer 2a, and connects signal lines of a small output current transformer 2b. It has a plurality of connection terminals 15 which are connector terminals. And in this modification, as shown in FIGS. 13 (a) to 13 (c), when the connector terminal 16b is inserted into the connection terminal 15, the plug 16 connected to the signal lines of the current transformers 2a and 2b is inserted. And a projection 16a for closing the connection terminal 14 which is a screw terminal. Further, in the present embodiment, the plug 16 has been described as the structure having the projection 16a, but the structure of the plug 16 may be any structure as long as the connection terminal can be closed.
  • the structure of the plug 16 is a structure that closes the connection terminal 15 which is a connector terminal when the connection terminal 14 which is a screw terminal is connected.
  • the power measuring instrument 3 includes a plurality of sets of connection terminals for measuring the power of the circuit including the main circuit and the branch circuit, and enables power measurement of multiple circuits. This is because when measuring from the main circuit to the branch circuit, it is necessary to measure a plurality of rated currents, and by making it possible to measure the power of multiple circuits, the power measuring instrument 3 can be miniaturized.
  • the present invention is not limited to the configuration of the above-described embodiment, and various modifications can be made without departing from the scope of the invention.
  • the types of the current transformers 2a and 2b and the burden resistances 311a and 311b are not limited to two, and may be at least two or more.
  • the type of the current transformer is not limited to the pair 5 ACT or the small CT, and a current transformer such as rated current 50A, 250A, 600A can also be used.
  • various types of different current transformers may be connected to predetermined positions of a plurality of load resistances connected in series, or to another predetermined position different from the predetermined position, according to the type. It is not limited to the position of the extreme end of.
  • all the above-mentioned embodiment and its modification can be performed combining with each other.

Abstract

An electricity meter (3) comprises: a current detection unit (31) that detects a current signal on the basis of output from a current transformers (2a, 2b); a voltage detection unit (32) that detects a voltage signal; and a power calculation unit (33) that calculates power on the basis of the voltage and current signals detected by the voltage detection unit (32) and current detection unit (31). The current detection unit (31) is provided with load resistors (311a, 311b). The current transformers (2a, 2b) have two types of different output, and depending on the type, are connected to the connection terminals (3a to 3c) on both ends of the load resistors (311a, 311b) or between the load resistors (311a and 311b). As a result of this configuration, the electricity meter (3) can connect current transformer (2a) and/or (2b), and can measure the electric power of a circuit within a distribution board.

Description

電力計測器Power meter
　本発明は、変流器（ＣＴ：Ｃｕｒｒｅｎｔ　Ｔｒａｎｓｆｏｒｍｅｒ）に接続されて分電盤内などにおける回路の電力を計測する電力計測器に関する。 The present invention relates to a power meter connected to a current transformer (CT) to measure the power of a circuit in a distribution board or the like.
　従来より、ビルディングなどの施設に設けられた分電盤内における回路の電力を計測する際、測定範囲拡大のために変流器が用いられる。この変流器の受け側回路には電力計測器が接続され、電力計測器は、変流器と接続される回路に負担抵抗を挿入して、この負担抵抗の両端の電圧を検出することで電流値を計測して電力演算を行うことができる。
　工場等では百Ａ~数百Ａの交流電流が通電されており、定格電流を通電すると５Ａの出力電流が得られる対５Ａと呼ばれる変流器（以下、対５ＡＣＴと記す）が使用される。この対５ＡＣＴは、配電系統の電流計測を行う際、いわゆる規格化された出力方式であり、接続可能な電力計測器と組み合わせることで、柔軟な電力計測システムの構成が可能となる。
　分電盤内における回路の電力計測には、従来、大きな電流が流れる主幹回路のみを計測する場合が殆どであるが、近年の消費電力の「見える化」の実現などのため、主幹回路から分岐された分電盤内の末端回路である分岐回路の電力も計測する必要がある。この分岐回路には、主幹回路からの電流が分流されるため、例えば数十Ａ程度の電流が流れる。なお、電力の「見える化」では、分電盤内の回路ごとの電力の情報を、ＬＡＮ経由でモニタを備えた管理装置などに表示する。
　そして、上記の対５ＡＣＴは、数百Ａといった定格電流の通電時に５Ａを出力するため、コアを大きくする必要があり、比較的形状が大きくなる。従って、定格電流が低い、分岐回路における数十Ａ程度の電流計測において、電流が通電される計測箇所に対５ＡＣＴを取付けようとした場合、形状が大きいために、取付けできない。また、分電盤内の複数の分岐回路の全ての電力計測を対５ＡＣＴで行うことは、分電盤内のスペース上問題がある。
　このため、分岐回路の電流計測においては、対５ＡＣＴではなく、出力電流が数ｍＡ程度である小型の変流器（以下、小型ＣＴと記す）が用いられる。この小型ＣＴの出力電流は、対５ＡＣＴの約１０００分の一であるため、鉄心コアや巻き線を小型化することができる。それゆえ、小型ＣＴは、分電盤内の比較的電流の低い分岐回路等の電流計測用として、対５ＡＣＴでは形状の制約上用いることができない箇所に用いることが可能となる。このように、分電盤内の設置スペースに応じて、種類の異なる変流器を使い分ける必要がある。
　次に、変流器に接続され、電力計測器に備わる負担抵抗に関して図１５を参照して説明する。図１５（ａ）に示すように、小型ＣＴ１５１は出力電流が数ｍＡとなるため、受け側回路である電力計測器１５２の電流検出部１５３に備える負担抵抗１５４には数Ωの抵抗値のものを用いる。電流検出部１５３は、この負担抵抗１５４の両端の電圧を検出することで電流値を計測し、電力演算部１５５に出力する。一方、図１５（ｂ）に示すように、対５ＡＣＴ１５６では出力電流が最大５Ａとなるため、数ｍΩのシャント抵抗１５７に接続され、電流検出部１５３は、このシャント抵抗１５７の両端の電圧を検出することで電流値を計測し、電力演算部１５５に出力する。
特開平７−２２９９２７号公報 Conventionally, when measuring the power of a circuit in a distribution board provided in a facility such as a building, a current transformer is used to expand the measurement range. A power measuring device is connected to the receiving side circuit of this current transformer, and the power measuring device inserts a burden resistance into the circuit connected to the current transformer, and detects the voltage across the burden resistance. The current value can be measured to perform power calculation.
In a factory or the like, an alternating current of 100 A to several hundreds A is supplied, and a current transformer called pair 5A (hereinafter referred to as a pair 5 ACT) is used which can obtain 5 A of output current when the rated current is applied. The pair 5 ACT is a so-called standardized output method when performing current measurement of a distribution system, and by combining it with a connectable power measuring instrument, a flexible power measuring system can be configured.
Conventionally, it has been the case that in most cases only the main circuit through which a large current flows is measured for measuring the power of the circuits in the distribution board, but branch from the main circuit for the realization of "visualization" of power consumption in recent years. It is also necessary to measure the power of the branch circuit which is the terminal circuit in the distributed board. In this branch circuit, a current of about several tens of Amps flows, for example, because the current from the main circuit is shunted. In the "visualization" of power, information on power of each circuit in the distribution board is displayed on a management apparatus or the like equipped with a monitor via a LAN.
Further, since the pair 5 ACT outputs 5 A when the rated current such as several hundred A is supplied, the core needs to be enlarged, and the shape becomes relatively large. Therefore, when trying to attach the pair 5 ACT to the measurement point where the current is applied in the current measurement of about several tens A in the branch circuit where the rated current is low, the attachment is impossible because the shape is large. In addition, there is a problem in space in the distribution board to perform all the power measurement of the plurality of branch circuits in the distribution board with the pair 5 ACT.
Therefore, in the current measurement of the branch circuit, not the pair 5 ACT but a small-sized current transformer (hereinafter referred to as a small CT) having an output current of about several mA is used. Since the output current of this small CT is about 1/1000 of that of the pair 5 ACT, the core and winding of the core can be miniaturized. Therefore, the small CT can be used at a place where the pair 5 ACT can not be used due to the restriction of the shape, for example, for current measurement such as a branch circuit with a relatively low current in the distribution board. Thus, different types of current transformers need to be used properly depending on the installation space in the distribution board.
Next, the load resistance connected to the current transformer and provided to the power measuring instrument will be described with reference to FIG. As shown in FIG. 15A, since the small CT 151 has an output current of several mA, the burden resistance 154 provided in the current detection unit 153 of the power measuring instrument 152 which is the receiving side circuit has a resistance value of several Ω. Use The current detection unit 153 measures the current value by detecting the voltage at both ends of the burden resistor 154, and outputs the current value to the power calculation unit 155. On the other hand, as shown in FIG. 15B, since the output current is 5 A at maximum in the pair 5 ACT 156, it is connected to the shunt resistor 157 of several mΩ, and the current detection unit 153 detects the voltage across the shunt resistor 157 The current value is measured and output to the power calculation unit 155.
Unexamined-Japanese-Patent No. 7-229927 gazette
　このように、小型ＣＴ及び対５ＡＣＴなどの種類の異なる変流器は、その出力電流がそれぞれ大きく異なるため、接続される回路の負担抵抗の抵抗値が異なる。具体的には、図１５に示すように、小型ＣＴ１５１と対５ＡＣＴ１５６とでは出力電流の大きさが１０００倍程度の差があり、対５ＡＣＴ１５６に接続される負担抵抗は数ｍΩ、小型ＣＴ１５１に接続される負担抵抗は数Ωとなる。このため、種類の異なる変流器を使用して回路の電力計測を行うには、変流器の種類に応じて、入力端子をそれぞれの出力電流の大きさで分けた別々の計測回路部、又は別々の電力計測器が必要となり、コストを要するという問題がある。
　ここで、組立てが容易で、取付所要面積が小さい、測定精度の高い、また被検出電流の大きさが異なっても容易に適合できる変流器が特許文献１に開示されている。
　しかしながら、上記特許文献１では、変流器を１種類使用して、抵抗器を切り替えることで大きさの異なる電流測定を実現するものであり、種類の異なる変流器を用いて電力を計測するものではない。 Thus, since the output currents of the different types of current transformers such as the small CT and the pair 5 ACT are largely different, the resistance value of the burden resistance of the connected circuit is different. Specifically, as shown in FIG. 15, there is a difference of about 1000 times in the magnitude of the output current between the small CT 151 and the pair 5 ACT 156, and the burden resistance connected to the pair 5 ACT 156 is several mΩ, Load resistance is several Ω. Therefore, in order to measure the power of the circuit using different types of current transformers, separate measurement circuit units in which the input terminals are divided according to the magnitude of each output current according to the type of current transformers, Or, there is a problem that separate power measuring devices are required, which is costly.
Here, Patent Document 1 discloses a current transformer that is easy to assemble, has a small mounting required area, has a high measurement accuracy, and can be easily adapted even if the magnitude of the detected current is different.
However, in Patent Document 1 above, one type of current transformer is used to realize current measurement with different sizes by switching resistors, and power is measured using different types of current transformers. It is not a thing.
　本発明は、上記課題に鑑みてなされたものであり、電力計測器内の回路切替を行う手間を要せず、出力の異なる複数種の変流器のいずれをも電流検出部に接続可能とし、分電盤内などにおける回路の電力を計測できる電力計測器を提供することを目的とする。
　本発明の一実施の形態によれば、回路から電圧信号を検出する電圧検出部と、前記回路に取り付けられた変流器からの出力に基づいて電流信号を検出する電流検出部と、前記電圧検出部及び電流検出部で検出される電圧信号及び電流信号に基づいて電力演算する電力演算部と、を備える電力計測器において、前記電流検出部は、少なくとも２種類以上の負担抵抗と、前記変流器からの出力を信号処理する信号処理回路とを備え、前記電流検出部には、少なくとも２種類以上の出力の異なる変流器が接続できる電力計測器を提供する。
　前記電流検出部に備えられる２種類の負担抵抗は直列に接続され、前記２種類の出力の異なる変流器はその種類に応じて前記直列に接続された負担抵抗の所定位置、又は前記所定位置と異なる別の所定位置に接続される、ことが好ましい。
　前記電流検出部に備えられる２種類の負担抵抗は直列に接続され、前記直列に接続された負担抵抗のうち少なくとも１つの負担抵抗には、導通用のリレーが並列に接続され、前記変流器は前記直列に接続された負担抵抗の最両端に接続される、ことが好ましい。
　前記電流検出部は、前記直列接続された負担抵抗の一端部に接続されて前記２種類の出力の異なる変流器の出力の基準となる信号線が接続される共通の接続端子、及び前記所定位置及び前記別の所定位置に接続されて前記２種類の出力の異なる変流器の他の信号線が接続される個別の接続端子と、前記個別の接続端子から前記電力演算部に繋がる前記信号線の経路を選択する回路切替機能を有したマルチプレクサと、をさらに備える、ことが好ましい。
　前記電流検出部に備えられる２種類以上の負担抵抗は直列に接続され、前記直列に接続された負担抵抗間には、前記異なる種類の変流器で共用とせず、変流器の種類ごとに個別に２つの個別接続端子が設けられる、ことが好ましい。
　前記直列に接続された少なくとも２種類以上の負担抵抗のうち、抵抗値の最も大きな前記負担抵抗の両端に設けられる接続端子は、専用のコネクタ端子以外は接続できない構造を有する、ことが好ましい。
　前記回路は、主幹回路及び当該主幹回路から分岐した複数の分岐回路を含み、前記電流検出部は、前記少なくとも２種類以上の出力の異なる変流器の信号線に接続する複数の接続端子をさらに備え、前記複数の接続端子は、これら回路ごとに、隣接して配置される、ことが好ましい。
　前記複数の接続端子は、出力の大きな前記変流器の信号線に接続するネジ端子、及び出力の小さな前記変流器の信号線に接続するコネクタ端子を含み、前記変流器の信号線と接続されたプラグは、前記ネジ端子又は前記コネクタ端子の一方との接続を行うと、他方の接続端子を塞ぐ構造を有する、ことが好ましい。
　前記電流検出部に備えられる２種類以上の負担抵抗は直列に接続され、前記直列に接続された負担抵抗に接続される基準電位側の信号線を、グランドである０Ｖ以外の所定の基準電位に接続する、ことが好ましい。
　前記電力計測器は、多回路の電力計測が可能である、ことが好ましい。
　前記電流検出部に備えられる２種類以上の負担抵抗は並列に接続され、前記電流検出部は、前記並列に配置された負担抵抗の一端側に接続され、前記変流器の出力の電流経路を前記並列に接続された負担抵抗のいずれかの経路に切り替える回路切替器をさらに備え、前記少なくとも２種類以上の出力の異なる変流器は、前記並列に接続された負担抵抗の両端側に接続される、ことが好ましい。
発明の効果
　本発明に係る電力計測器によれば、少なくとも２種類以上の負担抵抗が接続された電流検出部を備え、変流器は、その種類に応じて、負担抵抗の所定位置、又は当該所定位置と異なる別の所定位置に接続すればよい。従って、種類の異なる変流器を同一の電力計測器に接続可能となり、分電盤内などにおける回路の電力を計測することができる。 The present invention has been made in view of the above problems, and it is possible to connect any one of a plurality of current transformers with different outputs to the current detection unit without the need to perform circuit switching in the power measuring instrument. , And a power measuring device capable of measuring the power of a circuit in a distribution board or the like.
According to an embodiment of the present invention, there is provided a voltage detection unit that detects a voltage signal from a circuit, a current detection unit that detects a current signal based on an output from a current transformer attached to the circuit, and the voltage In a power measuring device including a detection unit and a power calculation unit that calculates power based on a current signal and a voltage signal detected by the current detection unit, the current detection unit includes at least two types of burden resistances, and And a signal processing circuit for processing the output from the flow device. The current detection unit provides a power measuring device to which at least two or more different current transformers having different outputs can be connected.
The two types of load resistances provided in the current detection unit are connected in series, and the current transformers with different outputs of the two types are at predetermined positions of the load resistances connected in series according to their types, or the predetermined positions Preferably, it is connected to another predetermined position different from
Two types of load resistances provided in the current detection unit are connected in series, and a relay for conduction is connected in parallel to at least one of the load resistances connected in series, and the current transformer Is preferably connected to the extreme ends of the series connected load resistors.
The current detection unit is a common connection terminal connected to one end of the series-connected load resistor and connected to a signal line serving as a reference of the outputs of the two different types of outputs of the current transformers; The individual connection terminal connected to the position and the another predetermined position and to which the other signal line of the current transformer different in the two types of outputs is connected, and the signal connected from the individual connection terminal to the power calculation unit Preferably, the multiplexer further comprises a multiplexer having a circuit switching function for selecting a path of a line.
The two or more types of load resistances provided in the current detection unit are connected in series, and the load resistances connected in series are not shared by the different types of current transformers, and each type of current transformer is used. Preferably, two separate connection terminals are provided individually.
Among the at least two or more types of load resistances connected in series, it is preferable that the connection terminals provided at both ends of the load resistance having the largest resistance value have a structure that can not be connected except for dedicated connector terminals.
The circuit includes a main circuit and a plurality of branch circuits branched from the main circuit, and the current detection unit further includes a plurality of connection terminals connected to signal lines of different current transformers of at least two or more types of outputs. It is preferable that the plurality of connection terminals be disposed adjacent to each other for each of the circuits.
The plurality of connection terminals include a screw terminal connected to a signal line of the current transformer with a large output, and a connector terminal connected to a signal line of the current transformer of a small output, and the signal line of the current transformer It is preferable that the connected plug has a structure that closes the other connection terminal when the connection with one of the screw terminal and the connector terminal is performed.
The signal line on the reference potential side, which is connected in series with two or more types of load resistances provided in the current detection unit, is connected to the load resistance connected in series to a predetermined reference potential other than 0 V which is ground. It is preferable to connect.
Preferably, the power meter is capable of multi-circuit power measurement.
Two or more types of burden resistances provided in the current detection unit are connected in parallel, the current detection unit is connected to one end of the burden resistances arranged in parallel, and the current path of the output of the current transformer is The circuit switching device for switching to any path of the load resistances connected in parallel is further provided, and the current transformers having different outputs of at least two or more types are connected to both ends of the load resistances connected in parallel. Is preferred.
According to the power meter according to the present invention, includes a current detector for at least two types of load resistor is connected, the current transformer, depending on the type, a predetermined position of the load resistance, or the It may be connected to another predetermined position different from the predetermined position. Therefore, different types of current transformers can be connected to the same power meter, and the power of the circuit in the distribution board or the like can be measured.
　本発明の目的及び特徴は以下のような添付図面と好ましい実施例の説明により明確になる。
本発明の実施の形態１に係る電力計測器を備えた電力計測システムの全体構成図である。 上記電力計測器の機能ブロック図である。 上記電力計測器に備わる電流検出部の回路図である。 上記実施の形態１の変形例１に係る電力計測器に備わる電流検出部の回路図である。 上記実施の形態１の変形例２に係る電力計測器に備わる電流検出部の回路図である。 上記実施の形態１の変形例３に係る電力計測器に備わる電流検出部の回路図である。 上記実施の形態１の変形例４に係る電力計測器に備わる電流検出部の回路図である。 本発明の実施の形態２に係る電力計測器に備わる電流検出部の回路図である。 本発明の実施の形態３に係る電力計測器に備わる電流検出部の回路図である。 上記実施の形態３の変形例１に係る電力計測器に備わる電流検出部の回路図である。 上記実施の形態３の変形例２に係る電力計測器に備わる電流検出部の回路図である。 （ａ）本発明の実施の形態４に係る電力計測器の正面図、（ｂ）同電力計測器の下面図、（ｃ）同電力計測器の上面図である。 （ａ）上記実施の形態４の変形例１に係る電力計測器に接続される変流器のプラグの側面図、（ｂ）同プラグの斜視図、（ｃ）同プラグの別の側面図である。 （ａ）上記実施の形態４の変形例２に係る電力計測器の正面図、（ｂ）同電力計測器の下面図、（ｃ）同電力計測器の上面図である。 （ａ）従来の電力計測器における電流検出部の回路図、（ｂ）従来の別の電力計測器における電流検出部の回路図である。 The objects and features of the present invention will become apparent from the following description of the accompanying drawings and the preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram of the electric power measurement system provided with the electric power measurement device which concerns on Embodiment 1 of this invention. It is a functional block diagram of the above-mentioned electric power measurement instrument. It is a circuit diagram of the current detection part with which the above-mentioned electric power measurement instrument is equipped. FIG. 13 is a circuit diagram of a current detection unit provided in the power measuring instrument according to the first modification of the first embodiment. FIG. 16 is a circuit diagram of a current detection unit provided in the power measuring instrument according to the second modification of the first embodiment. FIG. 16 is a circuit diagram of a current detection unit provided in the power measuring instrument according to the third modification of the first embodiment. FIG. 16 is a circuit diagram of a current detection unit provided in the power measuring instrument according to the fourth modification of the first embodiment. It is a circuit diagram of the current detection part with which the electric power measurement instrument concerning Embodiment 2 of this invention is equipped. It is a circuit diagram of an electric current detection part with which a power measuring instrument concerning Embodiment 3 of the present invention is equipped. FIG. 21 is a circuit diagram of a current detection unit provided in the power measuring instrument according to the first modification of the third embodiment. FIG. 21 is a circuit diagram of a current detection unit provided in the power measuring instrument according to the second modification of the third embodiment. (A) The front view of the electric power measurement instrument which concerns on Embodiment 4 of this invention, (b) The bottom view of the electric power measurement instrument, (c) It is a top view of the electric power measurement instrument. (A) A side view of the plug of the current transformer connected to the power measuring instrument according to the first modification of the fourth embodiment, (b) a perspective view of the same plug, (c) another side view of the same plug is there. (A) The front view of the electric power measurement instrument which concerns on the modification 2 of the said Embodiment 4, (b) The bottom view of the electric power measurement instrument, (c) It is a top view of the electric power measurement instrument. (A) A circuit diagram of a current detection unit in a conventional power meter, (b) A circuit diagram of a current detection unit in another conventional power meter.
　以下、本発明の実施の形態について添付図面に基づいて説明する。図面全体において同一又は類似する部分については同一参照符号を付して説明を省略する。
　（実施の形態１）
　本発明の実施の形態１に係る電力計測器について図面を参照して説明する。図１に示すように、電力計測システムＳは、分電盤１、種類の異なる変流器２ａ，２ｂ、電力計測器３、監視装置４、負荷５、及びブレーカ６ａ，６ｂ，６ｃを備える。この電力計測システムＳは、例えばオフィスビル内や一般住宅内において、分電盤１から電力供給を受ける照明器具やパソコンなどの様々な負荷５の消費電力を監視する。ここで、図１は三相３線式を用いる電線などからの電力計測のための構成を示しており、例えば、Ｒ／Ｔ相に変流器２ａ，２ｂを取付け、電流値を計測することを示している。
　分電盤１は、外部からビル内や宅内に供給される商用電源を、電線７を介して一次側に受ける主幹回路と、主幹回路の２次側から分岐した電路に介装される複数の分岐回路とを備える。各分岐回路には照明器具やパソコンのほか、空調機器やＩＨ（誘導加熱、Ｉｎｄｕｃｔｉｏｎ　Ｈｅａｔｉｎｇ）機器などの様々な負荷５が接続される。また、ブレーカ６ａは、主幹回路の電線７に接続された主幹ブレーカであり、ブレーカ６ｂは、主幹回路から分岐した複数の分岐回路に配設された分岐ブレーカである。
　種類の異なる変流器２ａ，２ｂは、各回路の電流を一定の割合で小さくして専用ケーブルである信号線８を介して電力計測器３に供給する。例えば変流器２ａは４００／５Ａ型の貫通式であれば、中心部を貫通する電線７に４００Ａの電流が流れた時に出力側の信号線８に５Ａが流れるようコイルの巻き数が構成されている。
　変流器２ａは、比較的大きな電流の流れる主幹回路を流れる主幹電流を定期的に計測するために設置され、本図においては、主幹回路の配線の１本ずつの電線に貫通され、電力計測器３と信号線８にて接続される。変流器２ｂは、比較的小さな電流の流れる各分岐回路を流れる分岐電流を分岐回路毎に定期的に計測するために設置され、分岐回路の電線の所定位置に貫通され、電力計測器３と信号線８にて接続される。なお、変流器２ａ，２ｂは、分割式などで主幹回路及び分岐回路の電線７に簡単に取り付けられ、信号線８として専用ケーブルを用いることで誤結線を未然に防止できる。
　電力計測器３は、変流器２ａ，２ｂと接続され、これら変流器２ａ，２ｂと接続される回路に挿入する負担抵抗を備え、変流器２ａ，２ｂが設置された回路の電力を計測する。電力計測器３は、通信線を介して監視装置４に演算結果を出力する。この電力計測器３は、例えば１０×１０ｃｍの大きさであり、分電盤１内の所定箇所に設置される。
　監視装置４は、モニタを有する専用のパソコンなどであり、各分岐回路の通電情報を管理し表示する監視ユニットである。監視装置４は、電力計測器３とＲＳ−４８５通信などでネットワーク接続され、各負荷５の電力使用に関するデータ収集を行い、データ解析のためグラフなどの表示を行う。監視装置４は、例えば一時間ごとや一日ごとの電力使用に関するデータを自動記録し、電力計測器３と接続されたネットワーク経由によるエネルギーの一括管理を行い、効率のよい電力使用量の「見える化」を実現する。
　負荷５は、分岐回路に接続された照明器具やパソコンのほか、空調機器やＩＨ機器などの様々な電気機器である。
　次に、本実施の形態１に係る電力計測器３の機能構成に関して図２を参照して説明する。図２は、便宜上、１つの変流器２ａまたは変流器２ｂについての電力計測のための構成を示している。電力計測器３は、変流器２ａ，２ｂの信号から電流信号を検出する電流検出部３１、回路の電圧信号を検出する電圧検出部３２、及び電流検出部３１における電流及び電圧検出部３２における電圧の各信号に基づいて電力演算する電力演算部３３を備える。
　電流検出部３１は、変流器２ａ，２ｂと接続される回路に挿入された負担抵抗３１１、所定周波数帯の信号を通過させるフィルタ３１２、及びフィルタ３１２を通過した電流信号の電圧値に所定値を加算する加算回路３１３を備える。
　電圧検出部３２は、図１に示すブレーカ６ｃなどを介して電線７と端子で接続され、電圧降圧回路３２１、フィルタ３２２、及び加算回路３２３を備える。電圧降圧回路３２１は、電圧を降圧させ、フィルタ３２２は、所定周波数帯の電圧信号を通過させ、加算回路３２３は、電圧波形が例えば０~５Ｖの範囲となるように電圧信号に適切なバイアスをかける。
　電力演算部３３は、電流検出部３１で計測された電流、及び電圧検出部３２で検出される電圧に基づいて、変流器２ａ，２ｂが取付けられた電線７に接続された負荷５に供給される電力を演算するマイコンである。この電力演算部３３は、Ａ／Ｄ変換部３３１，３３２、乗算部３３３、及び伝送回路部３３４を備える。
　Ａ／Ｄ変換部３３１は、電圧検出部３２から受信するアナログ信号をデジタル信号に変換する。Ａ／Ｄ変換部３３２は、電流検出部３１から受信するアナログ信号をデジタル信号に変換する。乗算部３３３は、Ａ／Ｄ変換部３３１及び３３２から出力される信号を乗算する回路であり、すなわち電力を算出する。伝送回路部３３４は、例えば、ＲＳ４８５などに準拠した２線式シリアル通信回路を有し、接続される通信線を介して相互に通信可能な監視装置４に電力演算値を送信する。
　次に、本実施の形態１に係る電力計測器３に備わる電流検出部３１の回路構成に関して図３を参照して説明する。電流検出部３１は、直列に接続された抵抗値の異なる２種類の負担抵抗３１１ａ，３１１ｂを備える。例えば、負担抵抗３１１ａは２．０Ωの抵抗、負担抵抗３１１ｂは１ｍΩのシャント抵抗である。なお、シャント抵抗は、大電流が流れる回路の電流計測用に作られた抵抗値が小さく高精度な抵抗器である。本実施の形態では電流検出部３１が２種類の変流器２ａ，２ｂに接続できる２種類の負担抵抗を備えることを説明したが、３種類以上の出力の異なる変流器に接続できる３種類以上の負担抵抗を備えても良い。
　また、負担抵抗３１１ａ，３１１ｂに接続される基準電位側の信号線は、０Ｖのグランド（ＧＮＤ）３１４に接続され、負担抵抗３１１ａの一端が加算回路３１３側に接続される。このように、電流検出部３１は、回路に挿入された負担抵抗３１１ａ，３１１ｂの最両端の電圧を測定して電流値を取得する信号処理回路を有する。
　電力計測器３は、それぞれが負担抵抗３１１ａ，３１１ｂの端部に接続された接続端子３ａ~３ｃを備える。変流器２ａ，２ｂは上述のように２種類の出力の異なるものであり、これら変流器２ａ，２ｂは、その種類に応じて、直列に接続された負担抵抗３１１ａ，３１１ｂの最両端、又は直列に接続された負担抵抗３１１ａ，３１１ｂの一端部と負担抵抗３１１ａ，３１１ｂとの間の所定位置に接続される。
　すなわち、比較的大きな電流を出力する対５ＡＣＴ２ａからの信号線は、回路に挿入される負担抵抗を小さくする必要があるため接続端子３ｂ，３ｃに接続される。一方、比較的小さな電流を出力する小型ＣＴ２ｂからの信号線は、変流器２ａ，２ｂと接続される回路に挿入される負担抵抗の抵抗値を大きくする必要があるため、接続端子３ａ，３ｃに接続される。このように、接続端子３ｃは、変流器２ａ，２ｂの出力の基準となる信号線を接続する共通の端子、接続端子３ａは、変流器２ｂの他の信号線を接続する個別の端子、接続端子３ｂは、変流器２ａの他の信号線を接続する個別の端子となる。
　以上のように、本実施の形態１に係る電力計測器３では、種類の異なる変流器２ａ，２ｂの信号線の接続位置を、直列に接続された負担抵抗３１１ａ，３１１ｂの抵抗値に応じて設けられた接続端子３ａ~３ｃを変更することで調節できる。このため、電力計測器３では、回路切替を行う手間を要せず、出力の異なる変流器２ａ，２ｂを同一の電流検出部３１に接続可能とし、分電盤１内における回路の電力を計測でき、電流計測器３の小型化や低コスト化を実現できる。
　さらに、電力計測器３に通信接続された監視装置４により、負荷５の消費電力を「見える化」して、どの負荷５の電力を削減すべきかを視覚的に理解できるなど、より効果的な省エネルギーを実現できる。
　なお、図３に示すように、複数の負担抵抗３１１ａ，３１１ｂの直列に接続する順序は、基準電位３１４側の負担抵抗３１１ｂの抵抗値を低くする。これにより、基準電位３１４に対して電圧降下を低く抑えることができ、電力計測器３の回路を安定に動作でき、ノイズ等の影響を低減できる。
　（第１の変形例）
　本実施の形態１の第１の変形例について、図４を参照して説明する。本変形例では、電流検出部３１は、直列に接続された負担抵抗３１１ａ，３１１ｂのうち、負担抵抗３１１ａには導通用のリレー３１５が並列に接続される。また、接続端子３ａ，３ｃは、直列に接続された負担抵抗３１１ａ，３１１ｂの最両端にそれぞれ接続され、出力の異なる変流器２ａ，２ｂは、同じ接続端子３ａ，３ｃに接続される。なお、本変形例では、上記実施の形態１とは異なり、直列に接続された負担抵抗３１１ａ，３１１ｂのうち、基準電位３１４側に抵抗値の大きい負担抵抗３１１ａが配置される。
　次に、本変形例に係る電力計測器３の動作に関して説明する。対５ＡＣＴ２ａが接続端子３ａ，３ｃに接続される場合には、リレー３１５が閉状態に、例えば、後述のスイッチ部１１（図１２参照）によって手動制御され、対５ＡＣＴ２ａからの出力電流がシャント抵抗３１１ｂのみを通過する回路となる。一方、小型ＣＴ２ｂが接続端子３ａ，３ｃに接続される場合には、リレー３１５が開状態に手動制御され、小型ＣＴ２ｂからの出力電流がシャント抵抗３１１ｂ及び負担抵抗３１１ａを通過する回路となる。このため、本変形例に係る電力計測器３では、１ａ接点構成を有するリレー３１５を用いた低コストの構成で、出力の異なる変流器２ａ，２ｂを同一の電流検出部３１に接続可能とする。
　（第２の変形例）
　本実施の形態１の第２の変形例について、図５を参照して説明する。本実施の形態１の第２の変形例は実施の形態１と類似しているが、例えば、手動制御されるマルチプレクサ３１６が負担抵抗３１１ａの両端に追加されたところが異なる。本変形例２において電流検出部３１は、直列に接続された２種類の負担抵抗３１１ａ，３１１ｂの端部の所定位置（つまり、負担抵抗３１１ａの両端）に接続され、接続端子３ａ~３ｃから電力演算部３３に繋がる信号線の経路を選択する回路切替機能を有したマルチプレクサ３１６をさらに備える。このため、本変形例２に係る電力計測器３では、回路切替器に信号用のマルチプレクサ３１６を使用し、出力の異なる変流器２ａ，２ｂを同一の電流検出部３１に接続可能として分電盤内における回路の電力を計測できる。従って、電力計測器３の小型化や低コスト化を実現できる。
　（第３の変形例）
　本実施の形態１の第３の変形例について、図６を参照して説明する。本変形例３において電流検出部３１は、上記変形例２の構成に加えて、信号の増幅率を可変可能なプログラマブルゲインアンプ３１７をさらに備える。このプログラマブルゲインアンプ３１７は、アナログスイッチ等を用いて増幅率を外部から設定できる増幅回路となる。変流器２ａ，２ｂの出力は、定格電流により異なるが、本変形例３に係る電力計測器３では、プログラマブルゲインアンプ３１７を用いてゲイン切替え、最適な信号で加算回路３１３に信号を入力し、電力演算部３３で電力演算することが可能となる。
　（第４の変形例）
　本実施の形態１の第４の変形例について、図７を参照して説明する。本変形例４では、負担抵抗３１１ａ，３１１ｂに接続される基準電位側の信号線を、グランドである０Ｖ以外の所定の基準電位Ｖｒｅｆに接続する。この構成により、電力演算部３３のＡＤ変換部３３２に信号を入力する際、基準電位Ｖｒｅｆを印加でき、負担抵抗３１１ａ，３１１ｂで得られる信号に対する加算回路３１３の構成が不要となり、信号線を直接、電力演算部３３のＡＤ変換部３３２に接続できる。従って、本変形例では、電流検出部３１の回路構成を簡略化して低コスト化を図り、且つ出力の異なる変流器２ａ，２ｂを同一の電流検出部３１に接続可能とし、分電盤内における回路の電力を計測できる。また、電力計測器３の小型化や低コスト化を実現できる。
　（実施の形態２）
　本発明の実施の形態２に係る電力計測器について、図８を参照して説明する。なお、上記実施の形態１と同様の構成には同一の符号を付し、その詳細な説明は省略する（以下同じ）。
　電流検出部３１は、それぞれの一端部に接続されて並列に配置された２つの負担抵抗３１１ａ，３１１ｂと、負担抵抗３１１ａ，３１１ｂの他端部に接続されて変流器２ａ，２ｂの出力の電流経路を負担抵抗３１１ａ，３１１ｂのいずれかとする回路構成を有する回路切替器（１ｃ接点構成の接触抵抗の低い有接点リレー）３１８と、加算回路３１３とを備える。変流器２ａ，２ｂの信号線は、その種類によらず、並列に接続された負担抵抗３１１ａ，３１１ｂの両端側に接続された接続端子３ａ，３ｃと接続される。
　このため、本実施の形態２では、変流器２ａ，２ｂのいずれを電力計測器３に接続しても、回路切替器３１８により、変流器２ａ，２ｂの種類に応じた適切な負担抵抗３１１ａ，３１１ｂに接続できる。従って、電流検出信号の信号レベルを所定のレベルまで上げて、Ｓ／Ｎ比を向上させて精度のよい電力の計測が可能となる。
　（実施の形態３）
　本発明の実施の形態３に係る電力計測器について、図９を参照して説明する。本実施の形態３では、電流検出部３１の直列に接続された負担抵抗３１１ａ，３１１ｂ間に設けられる接続端子３ｂ，３ｄは、異なる種類の変流器２ａ，２ｂで共用とせず、その種類ごとに個別に設けられる。すなわち、図９に示すように、小型ＣＴ２ｂの信号線と接続されるのは接続端子３ａ，３ｄであり、対５ＡＣＴ２ａの信号線と接続されるのは接続端子３ｂ，３ｃとなる。この構成により、出力の異なる変流器２ａ，２ｂを同一の電流検出部３１に接続可能とし、分電盤内の回路の電力を計測できると共に、変流器２ａ，２ｂからの電流の流れる経路を完全に別々にでき、より高精度な電力計測が可能となる。
　（第１の変形例）
　本実施の形態３の第１の変形例について、図１０を参照して説明する。本変形例では、抵抗値のより大きな負担抵抗３１１ａの両端に接続される接続端子３ａ，３ｄは、専用のコネクタ端子（プラグ）９ａ以外は接続できない構造、すなわちコネクタ端子９ａの形状と嵌合するコネクタ形状３ｅとなる。
　この構成により、本変形例では、対５ＡＣＴ２ａが、抵抗値の大きな負担抵抗３１１ａに接続され、負担抵抗３１１ａが焼損して誤結線による事故を未然に防ぐことが可能となる。また、コネクタ端子９ａの構造とすることで変流器２ａ，２ｂ及び電力計測器３間の施工性をよくすることができる。
　（第２の変形例）
　本実施の形態３の第２の変形例について、図１１を参照して説明する。本変形例では、コネクタ端子（プラグ）９ｂは、２以上の変流器（本図では小型ＣＴ２ｂの２台）からの信号線が接続可能な構造を有している。一方、電力計測器３には、その側面などにおいて、このコネクタ端子９ｂと嵌合する形状を有するコネクタ接続端子３ｆが形成される。この構成により、上記変形例１の効果に加えて、三相３線式を用いる電線などからの電力計測など、Ｒ／Ｓ／Ｔ相に取付けられる複数個の変流器２ａ，２ｂがセットとなった回路計測において、誤結線を未然に防止できる。
　（実施の形態４）
　本発明の実施の形態４に係る電力計測器について、図１２を参照して説明する。図１２（ａ）は本発明の実施の形態４に係る電力計測器の正面図、図１２（ｂ）は同電力計測器の下面図、図１２（ｃ）は同電力計測器の上面図である。本実施の形態４に係る電力計測器３は、表示部１０、スイッチ部１１、電圧入力端子１２、通信端子１３、対５ＡＣＴ接続端子１４、及び小型ＣＴ接続端子１５を備える。
　表示部１０は、各回路における電力計測結果を表示する液晶パネルなどである。スイッチ部１１は、変流器２ａ，２ｂの種類の設定、表示部１０の表示設定を行うための操作キーである。電圧入力端子１２は、電線と接続されて電圧極Ｓと電圧極Ｔの相関電圧などを検出するための入力端子である。通信端子１３は、監視装置４と接続され、ＲＳ−４８５通信などで用いる通信線を接続するネジ端子である。対５ＡＣＴ接続端子１４は、対５ＡＣＴ２ａからの信号線を接続するネジ端子である。小型ＣＴ接続端子１５は、小型ＣＴ２ｂからのコネクタ端子９ａが挿し込まれる差込口となるコネクタ端子である。
　主幹回路及び当該主幹回路から分岐した複数の分岐回路からなる回路は、左右方向に隣接して電力計測器３の側面に配置される。そして、点線Ｌの領域に示すように、接続端子１４、１５は、前後方向に、直線状に配置される。この配置構成により、本実施の形態４に係る電力計測器３では、同じ回路に、複数の変流器２ａ，２ｂを同時に接続することを視覚的に防止できる。また、本発明の実施の形態では上述の接続端子が電力計測器３の側面に配置されるものであると説明したが、上面、下面、または正面に配置されても良い。
　（第１の変形例）
　本実施の形態４の第１の変形例について、図１３を参照して説明する。電力計測器３は、上記図１２に示すように、出力の大きな変流器２ａの信号線を接続するネジ端子である複数の接続端子１４、及び出力の小さな変流器２ｂの信号線を接続するコネクタ端子である複数の接続端子１５を備えている。そして、本変形例では、図１３（ａ）~（ｃ）に示すように、変流器２ａ，２ｂの信号線に接続されるプラグ１６は、コネクタ端子１６ｂが接続端子１５に挿入されると、ネジ端子である接続端子１４を塞ぐ突起部１６ａを有している。また、本実施の形態ではプラグ１６が突起部１６ａを有する構造として説明したが、接続端子を塞ぐことができれば、プラグ１６の構造はどのような構造であっても構わない。
　この構成により、同じ回路において、同時に２種類の変流器２ａ，２ｂが接続されることがなくなり、小型ＣＴ２ｂと対５ＡＣＴ２ａの同時接続による誤接続を防止できる。なお、プラグ１６の構造を、ネジ端子である接続端子１４を接続するとコネクタ端子である接続端子１５を塞ぐ構造とすることも考え得る。
　（第２の変形例）
　本実施の形態４の第２の変形例について、図１４を参照して説明する。本変形例では、点線Ｌ２の領域で示すように、電力計測器３の接続端子は、変流器２ａ，２ｂで計測される一部の回路において、ネジ端子の接続端子１４のみの構成となる。
　これは、分電盤内の主幹回路と分岐回路を計測する際、主幹回路は定格電流が大きくなるため対５ＡＣＴ２ａで、分岐回路は定格電流が比較的低くなるため小型ＣＴ２ｂを選定し計測する。従って、電力計測器３では、所定の回路は５ＡＣＴ２ａの接続端子１４のみ、所定の回路は小型ＣＴ２ｂの接続端子１５又は対５ＡＣＴ２ａの接続端子１４の選択式とするため、全ての回路を選択式の接続端子１４，１５の構造にするよりも低コストで構成できる。なお、図示はしていないが、一部の計測回路を小型ＣＴ２ｂ用の接続端子１５のみの構成とすることも考え得る。
　そして、上記各実施の形態に係る電力計測器３は、主幹回路及び分岐回路からなる回路の電力を計測するための接続端子の組を複数備えて、多回路の電力計測を可能とする。これは、主幹回路から分岐回路までを計測する際、複数の定格電流の計測が必要であり、多回路の電力計測を可能とすることにより、電力計測器３の小型化を図れるためである。
　なお、本発明は、上記実施の形態の構成に限られず、発明の趣旨を変更しない範囲で種々の変形が可能である。例えば、変流器２ａ，２ｂや負担抵抗３１１ａ，３１１ｂの種類は２種類に限定されるものではなく、少なくとも２種類以上であればよい。また、変流器の種類は対５ＡＣＴや小型ＣＴに限定されるものではなく、定格電流５０Ａ，２５０Ａ，６００Ａなどの変流器を使用することもできる。さらに、様々な種類の異なる変流器は、その種類に応じて、直列に接続された複数の負担抵抗の所定位置、又は当該所定位置と異なる別の所定位置に接続されればよく、負担抵抗の最両端の位置に限定されるものではない。
　ここで、上述のすべての実施の形態及びその変形例は互いに組み合わせて行うことができる。
　以上、本発明の好ましい実施の形態が説明されているが、本発明はこれらの特定の実施の形態に限られるものではなく、請求範囲の範疇から離脱しない多様な変更及び変形が可能であり、それも本発明の範疇内に属する。 Hereinafter, embodiments of the present invention will be described based on the attached drawings. The same reference numerals are given to the same or similar parts throughout the drawings and the description will be omitted.
Embodiment 1
A power measuring device according to Embodiment 1 of the present invention will be described with reference to the drawings. As shown in FIG. 1, the power measurement system S includes a distribution board 1, different types of current transformers 2 a and 2 b, a power measurement device 3, a monitoring device 4, a load 5, and breakers 6 a, 6 b and 6 c. The power measurement system S monitors the power consumption of various loads 5 such as lighting fixtures and personal computers that receive power supply from the distribution board 1 in, for example, an office building or a general house. Here, FIG. 1 shows a configuration for power measurement from an electric wire or the like using a three-phase three-wire system, for example, attaching current transformers 2a and 2b to the R / T phase and measuring a current value Is shown.
Distribution board 1 receives a commercial power supply externally supplied to the interior of a building or a house on the primary side via wire 7, and a plurality of power supply paths interposed between the secondary side of the main circuit and the main circuit. And a branch circuit. In addition to lighting devices and personal computers, various loads 5 such as air conditioners and IH (Induction Heating) devices are connected to each branch circuit. The breaker 6a is a main breaker connected to the electric wire 7 of the main circuit, and the breaker 6b is a branch breaker disposed in a plurality of branch circuits branched from the main circuit.
The different types of current transformers 2a and 2b reduce the current of each circuit at a constant rate and supply the power measuring instrument 3 via the signal line 8 which is a dedicated cable. For example, if the current transformer 2a is a 400/5 A penetration type, the number of turns of the coil is configured so that 5 A flows in the signal line 8 on the output side when a current of 400 A flows in the electric wire 7 penetrating the central portion. ing.
The current transformer 2a is installed to periodically measure the main current flowing in the main circuit through which a relatively large current flows, and in the figure, each of the wires of the main circuit is penetrated to measure the power And the signal line 8. The current transformer 2b is installed to periodically measure the branch current flowing in each branch circuit through which a relatively small current flows, and is penetrated to a predetermined position of the electric wire of the branch circuit. It is connected by the signal line 8. The current transformers 2a and 2b can be easily attached to the electric wire 7 of the main circuit and the branch circuit in a split type or the like, and erroneous connection can be prevented by using a dedicated cable as the signal line 8.
The power measuring device 3 is connected to the current transformers 2a and 2b, has a load resistance to be inserted in the circuit connected to the current transformers 2a and 2b, and the power of the circuit in which the current transformers 2a and 2b are installed is measure. The power measuring device 3 outputs the calculation result to the monitoring device 4 via the communication line. The power measuring instrument 3 has a size of, for example, 10 × 10 cm, and is installed at a predetermined position in the distribution board 1.
The monitoring device 4 is a dedicated personal computer or the like having a monitor, and is a monitoring unit that manages and displays energization information of each branch circuit. The monitoring device 4 is network-connected to the power measuring instrument 3 via RS-485 communication or the like, performs data collection on the power use of each load 5, and displays a graph or the like for data analysis. The monitoring device 4 automatically records, for example, data on power usage on an hourly or daily basis, performs batch management of energy via a network connected to the power measuring instrument 3, and “sees” efficient power usage To achieve the
The load 5 is various electrical devices such as an air conditioner and an IH device as well as a lighting fixture and a personal computer connected to the branch circuit.
Next, the functional configuration of the power measuring device 3 according to the first embodiment will be described with reference to FIG. FIG. 2 shows a configuration for power measurement of one current transformer 2a or current transformer 2b for convenience. The power measuring device 3 detects the current signal from the signals of the current transformers 2a and 2b, the voltage detection unit 32 detects the voltage signal of the circuit, and the current and voltage detection unit 32 in the current detection unit 31. A power calculator 33 is provided to calculate power based on each signal of voltage.
The current detection unit 31 has a load resistance 311 inserted in a circuit connected to the current transformers 2a and 2b, a filter 312 for passing a signal of a predetermined frequency band, and a voltage value of a current signal passed through the filter 312. And an adder circuit 313 for adding
The voltage detection unit 32 is connected to the electric wire 7 at a terminal via the breaker 6 c shown in FIG. 1 and the like, and includes a voltage step-down circuit 321, a filter 322, and an addition circuit 323. The voltage step-down circuit 321 steps down the voltage, the filter 322 passes a voltage signal of a predetermined frequency band, and the addition circuit 323 appropriately biases the voltage signal so that the voltage waveform is in the range of 0 to 5 V, for example. Call.
The power calculation unit 33 supplies the load 5 connected to the wire 7 to which the current transformers 2a and 2b are attached, based on the current measured by the current detection unit 31 and the voltage detected by the voltage detection unit 32. Is a microcomputer that calculates the power consumption. The power calculation unit 33 includes A / D conversion units 331 and 332, a multiplication unit 333, and a transmission circuit unit 334.
The A / D conversion unit 331 converts an analog signal received from the voltage detection unit 32 into a digital signal. The A / D conversion unit 332 converts an analog signal received from the current detection unit 31 into a digital signal. The multiplication unit 333 is a circuit that multiplies the signals output from the A / D conversion units 331 and 332, that is, calculates the power. The transmission circuit unit 334 has, for example, a two-wire serial communication circuit conforming to RS 485 or the like, and transmits the calculated power value to the monitoring device 4 capable of mutual communication via the connected communication line.
Next, the circuit configuration of the current detection unit 31 provided in the power measuring instrument 3 according to the first embodiment will be described with reference to FIG. The current detection unit 31 includes two types of burden resistors 311 a and 311 b connected in series and different in resistance value. For example, the burden resistance 311 a is a 2.0 Ω resistance, and the burden resistance 311 b is a 1 mΩ shunt resistance. The shunt resistor is a high-precision resistor with a small resistance value made for current measurement of a circuit through which a large current flows. Although it has been described in the present embodiment that the current detection unit 31 includes two types of load resistances that can be connected to two types of current transformers 2a and 2b, three types of current collectors that can be connected to three or more types of different current transformers The above burden resistance may be provided.
The signal line on the reference potential side connected to the burden resistors 311 a and 311 b is connected to the ground (GND) 314 at 0 V, and one end of the burden resistor 311 a is connected to the adding circuit 313 side. As described above, the current detection unit 31 has a signal processing circuit that measures the voltage at the both ends of the load resistors 311 a and 311 b inserted in the circuit to obtain the current value.
The power measuring device 3 includes connection terminals 3a to 3c connected to the end portions of the load resistors 311a and 311b, respectively. As described above, the current transformers 2a and 2b are different in the two types of outputs, and these current transformers 2a and 2b are, depending on the type, the extreme ends of the load resistors 311a and 311b connected in series, Alternatively, it is connected to a predetermined position between one end of the load resistors 311a and 311b connected in series and the load resistors 311a and 311b.
That is, the signal line from the pair 5 ACT 2 a that outputs a relatively large current is connected to the connection terminals 3 b and 3 c because it is necessary to reduce the burden resistance inserted in the circuit. On the other hand, since it is necessary to increase the resistance value of the load resistance inserted in the circuit connected to the current transformers 2a and 2b, the signal line from the small CT 2b which outputs a relatively small current, the connection terminals 3a and 3c. Connected to Thus, the connection terminal 3c is a common terminal for connecting the signal line serving as the reference of the outputs of the current transformers 2a and 2b, and the connection terminal 3a is an individual terminal for connecting the other signal lines of the current transformer 2b. The connection terminal 3b is an individual terminal for connecting another signal line of the current transformer 2a.
As described above, in the power measuring device 3 according to the first embodiment, the connection positions of the signal lines of the different types of current transformers 2a and 2b are determined according to the resistance value of the burden resistors 311a and 311b connected in series. The adjustment can be performed by changing the connection terminals 3a to 3c provided. For this reason, in the power measuring device 3, it is possible to connect current transformers 2a and 2b having different outputs to the same current detection unit 31 without the need to perform circuit switching, and the power of the circuit in the distribution board 1 can be obtained. Measurement can be performed, and downsizing and cost reduction of the current measuring device 3 can be realized.
Furthermore, the monitoring device 4 communicatively connected to the power measuring instrument 3 makes it possible to “visualize” the power consumption of the load 5 so that it is possible to visually understand which load 5 should be reduced in power, etc. Energy saving can be realized.
In addition, as shown in FIG. 3, the order which connects several burden resistance 311a, 311b in series makes the resistance value of the burden resistance 311b at the side of the reference electric potential 314 low. Thereby, the voltage drop can be suppressed to a low level with respect to the reference potential 314, the circuit of the power measuring instrument 3 can operate stably, and the influence of noise and the like can be reduced.
(First modification)
A first modification of the first embodiment will be described with reference to FIG. In the present modification, in the current detection unit 31, of the burden resistors 311a and 311b connected in series, the relay 315 for conduction is connected in parallel to the burden resistor 311a. The connection terminals 3a and 3c are respectively connected to the extreme ends of the load resistors 311a and 311b connected in series, and the current transformers 2a and 2b different in output are connected to the same connection terminals 3a and 3c. In this modification, unlike the first embodiment, the burden resistance 311a having a large resistance value is disposed on the reference potential 314 side among the burden resistances 311a and 311b connected in series.
Next, the operation of the power measuring device 3 according to the present modification will be described. When the pair 5ACT 2a is connected to the connection terminals 3a and 3c, the relay 315 is manually controlled by, for example, the switch unit 11 (see FIG. 12) described later, and the output current from the pair 5ACT 2a is shunt resistor 311b. It becomes a circuit that only passes through. On the other hand, when the small CT 2b is connected to the connection terminals 3a and 3c, the relay 315 is manually controlled in the open state, and the output current from the small CT 2b passes through the shunt resistor 311b and the burden resistor 311a. Therefore, in the power measuring device 3 according to the present modification, it is possible to connect current transformers 2a and 2b having different outputs to the same current detection unit 31 with a low cost configuration using the relay 315 having a 1a contact configuration. Do.
(Second modification)
A second modified example of the first embodiment will be described with reference to FIG. The second modified example of the first embodiment is similar to the first embodiment, but differs in that, for example, a manually controlled multiplexer 316 is added to both ends of the burden resistor 311a. In the second modification, the current detection unit 31 is connected to a predetermined position (that is, both ends of the load resistance 311a) of the end of the two types of load resistances 311a and 311b connected in series, and power is supplied from the connection terminals 3a to 3c. The circuit further includes a multiplexer 316 having a circuit switching function of selecting a path of a signal line connected to the arithmetic unit 33. For this reason, in the power measuring device 3 according to the second modification, the signal switching multiplexer 316 is used as the circuit switching device, and current transformers 2a and 2b having different outputs can be connected to the same current detection unit 31 so that power distribution can be performed. It can measure the power of the circuit in the board. Therefore, downsizing and cost reduction of the power measuring instrument 3 can be realized.
(Third modification)
A third modified example of the first embodiment will be described with reference to FIG. In the third modification, in addition to the configuration of the second modification, the current detection unit 31 further includes a programmable gain amplifier 317 capable of changing the amplification factor of the signal. The programmable gain amplifier 317 is an amplification circuit that can set the amplification factor from the outside using an analog switch or the like. The outputs of the current transformers 2a and 2b differ depending on the rated current, but in the power measuring instrument 3 according to the third modification, gain switching is performed using the programmable gain amplifier 317, and a signal is input to the adding circuit 313 with an optimal signal. The power calculation unit 33 can calculate the power.
(The 4th modification)
A fourth modified example of the first embodiment will be described with reference to FIG. In the fourth modification, the signal line on the reference potential side connected to the load resistors 311a and 311b is connected to a predetermined reference potential Vref other than 0 V which is the ground. With this configuration, when a signal is input to the AD conversion unit 332 of the power calculation unit 33, the reference potential Vref can be applied, and the configuration of the addition circuit 313 for the signal obtained by the burden resistors 311a and 311b becomes unnecessary. , And can be connected to the AD conversion unit 332 of the power calculation unit 33. Therefore, in the present modification, the circuit configuration of the current detection unit 31 is simplified to achieve cost reduction, and the current transformers 2a and 2b having different outputs can be connected to the same current detection unit 31, and the inside of the distribution board Can measure the power of the circuit in In addition, downsizing and cost reduction of the power measuring instrument 3 can be realized.
Second Embodiment
A power measuring instrument according to a second embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and the detailed description thereof is omitted (the same applies to the following).
The current detection unit 31 is connected to two load resistors 311a and 311b connected in parallel to one end of the current detector 31 and the other end of the load resistors 311a and 311b, and the current detection unit 31 outputs the current transformers 2a and 2b. A circuit switching device (a contact relay with a low contact resistance with a 1c contact configuration) 318 having a circuit configuration in which the current path is one of the load resistors 311a and 311b, and an adder circuit 313 are provided. The signal lines of the current transformers 2a and 2b are connected to the connection terminals 3a and 3c connected to both ends of the load resistors 311a and 311b connected in parallel regardless of the type.
For this reason, in the second embodiment, even if any one of the current transformers 2a and 2b is connected to the power measuring instrument 3, the circuit switch 318 appropriately applies load resistance according to the type of the current transformers 2a and 2b. It can be connected to 311a and 311b. Therefore, the signal level of the current detection signal is raised to a predetermined level to improve the S / N ratio, thereby enabling accurate measurement of power.
Third Embodiment
The power measuring device according to the third embodiment of the present invention will be described with reference to FIG. In the third embodiment, the connection terminals 3b and 3d provided between the load resistors 311a and 311b connected in series in the current detection unit 31 are not shared by different types of current transformers 2a and 2b, but each type Provided separately. That is, as shown in FIG. 9, the connection terminals 3a and 3d are connected to the signal line of the small CT 2b, and the connection terminals 3b and 3c are connected to the signal line of the pair 5ACT 2a. With this configuration, current transformers 2a and 2b having different outputs can be connected to the same current detection unit 31, power of circuits in the distribution board can be measured, and a current flow path from current transformers 2a and 2b Can be completely separated, allowing more accurate power measurement.
(First modification)
A first modified example of the third embodiment will be described with reference to FIG. In this modification, connection terminals 3a and 3d connected to both ends of load resistance 311a having a larger resistance value can not be connected except for dedicated connector terminals (plugs) 9a, that is, they fit with the shape of connector terminals 9a. It becomes connector shape 3e.
With this configuration, in the present modification, the pair 5 ACT 2 a is connected to the burden resistance 311 a having a large resistance value, and the burden resistance 311 a can be burnt out to prevent an accident due to a misconnection in advance. Moreover, the workability between the current transformers 2a and 2b and the power measuring device 3 can be improved by adopting the structure of the connector terminal 9a.
(Second modification)
A second modified example of the third embodiment will be described with reference to FIG. In this modification, the connector terminal (plug) 9 b has a structure to which signal lines from two or more current transformers (two small CTs 2 b in this figure) can be connected. On the other hand, a connector connection terminal 3f having a shape fitted to the connector terminal 9b is formed on the side surface etc. of the power measuring instrument 3. With this configuration, in addition to the effects of the first modification, a plurality of current transformers 2a and 2b attached to the R / S / T phase, such as power measurement from electric wires using a three-phase three-wire system, Erroneous wiring can be prevented in advance in circuit measurement.
Embodiment 4
The power measuring device according to the fourth embodiment of the present invention will be described with reference to FIG. 12 (a) is a front view of the power measuring instrument according to Embodiment 4 of the present invention, FIG. 12 (b) is a bottom view of the same power measuring instrument, and FIG. 12 (c) is a top view of the same power measuring instrument. is there. The power measuring instrument 3 according to the fourth embodiment includes a display unit 10, a switch unit 11, a voltage input terminal 12, a communication terminal 13, a pair 5 ACT connection terminal 14, and a small CT connection terminal 15.
The display unit 10 is a liquid crystal panel or the like that displays the power measurement result in each circuit. The switch unit 11 is an operation key for setting the type of the current transformers 2 a and 2 b and setting the display of the display unit 10. The voltage input terminal 12 is an input terminal connected to the electric wire for detecting a correlation voltage between the voltage pole S and the voltage pole T and the like. The communication terminal 13 is a screw terminal connected to the monitoring device 4 and connecting a communication line used in RS-485 communication or the like. The pair 5 ACT connection terminal 14 is a screw terminal for connecting the signal line from the pair 5 ACT 2 a. The small CT connection terminal 15 is a connector terminal serving as an insertion port into which the connector terminal 9a from the small CT 2b is inserted.
A main trunk circuit and a circuit composed of a plurality of branch circuits branched from the main trunk circuit are disposed adjacent to each other in the lateral direction on the side surface of the power measuring instrument 3. Then, as shown in the area of the dotted line L, the connection terminals 14 and 15 are arranged linearly in the front-rear direction. By this arrangement configuration, in the power measuring device 3 according to the fourth embodiment, simultaneous connection of a plurality of current transformers 2a and 2b to the same circuit can be visually prevented. In the embodiment of the present invention, the above-described connection terminal is described as being disposed on the side surface of the power measuring instrument 3. However, the connection terminal may be disposed on the upper surface, the lower surface, or the front.
(First modification)
A first modified example of the fourth embodiment will be described with reference to FIG. As shown in FIG. 12, the power measuring instrument 3 connects a plurality of connection terminals 14 which are screw terminals for connecting signal lines of a large output current transformer 2a, and connects signal lines of a small output current transformer 2b. It has a plurality of connection terminals 15 which are connector terminals. And in this modification, as shown in FIGS. 13 (a) to 13 (c), when the connector terminal 16b is inserted into the connection terminal 15, the plug 16 connected to the signal lines of the current transformers 2a and 2b is inserted. And a projection 16a for closing the connection terminal 14 which is a screw terminal. Further, in the present embodiment, the plug 16 has been described as the structure having the projection 16a, but the structure of the plug 16 may be any structure as long as the connection terminal can be closed.
With this configuration, two types of current transformers 2a and 2b are not connected simultaneously in the same circuit, and erroneous connection due to simultaneous connection of the small CT 2b and the pair 5 ACT 2a can be prevented. In addition, it may be considered that the structure of the plug 16 is a structure that closes the connection terminal 15 which is a connector terminal when the connection terminal 14 which is a screw terminal is connected.
(Second modification)
A second modified example of the fourth embodiment will be described with reference to FIG. In this modification, as shown in the area of the dotted line L2, the connection terminal of the power measuring instrument 3 has only the configuration of the connection terminal 14 of the screw terminal in a part of the circuit measured by the current transformers 2a and 2b. .
This is because when the main circuit and branch circuit in the distribution board are measured, since the main circuit becomes larger in rated current due to the larger rated current, the branched circuit becomes smaller in rated current and the small CT 2b is selected and measured. Therefore, in the power measuring instrument 3, all circuits are selectively selected in order to select only the connection terminal 14 of 5ACT 2a as the predetermined circuit and the connection terminal 15 of the small CT 2b or the connection terminal 14 of the pair 5ACT 2a as the predetermined circuit. It can be configured at lower cost than the structure of the connection terminals 14 and 15. Although not shown in the drawings, it may be conceivable to configure only a part of the measurement circuit with the connection terminal 15 for the small CT 2 b.
The power measuring instrument 3 according to each of the above-described embodiments includes a plurality of sets of connection terminals for measuring the power of the circuit including the main circuit and the branch circuit, and enables power measurement of multiple circuits. This is because when measuring from the main circuit to the branch circuit, it is necessary to measure a plurality of rated currents, and by making it possible to measure the power of multiple circuits, the power measuring instrument 3 can be miniaturized.
The present invention is not limited to the configuration of the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the types of the current transformers 2a and 2b and the burden resistances 311a and 311b are not limited to two, and may be at least two or more. Further, the type of the current transformer is not limited to the pair 5 ACT or the small CT, and a current transformer such as rated current 50A, 250A, 600A can also be used. Furthermore, various types of different current transformers may be connected to predetermined positions of a plurality of load resistances connected in series, or to another predetermined position different from the predetermined position, according to the type. It is not limited to the position of the extreme end of.
Here, all the above-mentioned embodiment and its modification can be performed combining with each other.
Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these specific embodiments, and various changes and modifications can be made without departing from the scope of the claims. It also falls within the scope of the present invention.

Claims (11)

  1. 　回路から電圧信号を検出する電圧検出部と、前記回路に取り付けられた変流器からの出力に基づいて電流信号を検出する電流検出部と、前記電圧検出部及び電流検出部で検出される電圧信号及び電流信号に基づいて電力演算する電力演算部と、を備える電力計測器において、
    　前記電流検出部は、少なくとも２種類以上の負担抵抗と、前記変流器からの出力を信号処理する信号処理回路とを備え、
    　前記電流検出部には、少なくとも２種類以上の出力の異なる変流器が接続できることを特徴とする電力計測器。     A voltage detection unit that detects a voltage signal from a circuit, a current detection unit that detects a current signal based on an output from a current transformer attached to the circuit, a voltage detected by the voltage detection unit and the current detection unit And a power calculation unit that calculates power based on the signal and the current signal.
    The current detection unit includes at least two or more types of load resistors, and a signal processing circuit that processes an output from the current transformer.
    A power measuring instrument characterized in that at least two different current transformers having different outputs can be connected to the current detection unit.
  2. 　前記電流検出部に備えられる２種類の負担抵抗は直列に接続され、
    　前記２種類の出力の異なる変流器はその種類に応じて前記直列に接続された負担抵抗の所定位置、又は前記所定位置と異なる別の所定位置に接続される、ことを特徴とする請求項１に記載の電力計測器。     The two types of load resistors provided in the current detection unit are connected in series,
    The different current transformers of the two types of outputs are connected to predetermined positions of the load resistors connected in series according to their types, or to another predetermined position different from the predetermined position. The power meter according to 1.
  3. 　前記電流検出部に備えられる２種類の負担抵抗は直列に接続され、
    　前記直列に接続された負担抵抗のうち少なくとも１つの負担抵抗には、導通用のリレーが並列に接続され、
    　前記変流器は前記直列に接続された負担抵抗の最両端に接続される、ことを特徴とする請求項１記載の電力計測器。     The two types of load resistors provided in the current detection unit are connected in series,
    A relay for conduction is connected in parallel to at least one of the load resistors connected in series,
    The power measuring instrument according to claim 1, wherein the current transformer is connected to both ends of the series connected load resistance.
  4. 　前記電流検出部は、
    　前記直列接続された負担抵抗の一端部に接続されて前記２種類の出力の異なる変流器の出力の基準となる信号線が接続される共通の接続端子、及び前記所定位置及び前記別の所定位置に接続されて前記２種類の出力の異なる変流器の他の信号線が接続される個別の接続端子と、
    　前記個別の接続端子から前記電力演算部に繋がる前記信号線の経路を選択する回路切替機能を有したマルチプレクサと、をさらに備える、ことを特徴とする請求項２に記載の電力計測器。     The current detection unit
    A common connection terminal connected to one end of the series-connected burden resistor and to which a signal line serving as a reference of the outputs of the two different types of output current transformers is connected, the predetermined position and the other predetermined position Separate connection terminals connected in position to which other signal lines of different current transformers of the two types of outputs are connected;
    The power measuring instrument according to claim 2, further comprising: a multiplexer having a circuit switching function of selecting a path of the signal line connected from the individual connection terminal to the power calculation unit.
  5. 　前記電流検出部に備えられる２種類以上の負担抵抗は直列に接続され、
    　前記直列に接続された負担抵抗間には、前記異なる種類の変流器で共用とせず、変流器の種類ごとに個別に２つの個別接続端子が設けられる、ことを特徴とする請求項１に記載の電力計測器。     The two or more types of load resistors provided in the current detection unit are connected in series,
    The load resistances connected in series are not shared by the different types of current transformers, and two individual connection terminals are provided individually for each type of current transformer. The power meter described in.
  6. 　前記直列に接続された少なくとも２種類以上の負担抵抗のうち、抵抗値の最も大きな前記負担抵抗の両端にに接続された接続端子は、専用のコネクタ端子以外は接続できない構造を有する、ことを特徴とする請求項５記載の電力計測器。 Among the at least two or more types of load resistances connected in series, the connection terminals connected to both ends of the load resistance having the largest resistance value have a structure that can not be connected except for dedicated connector terminals. The power meter according to claim 5, wherein
  7. 　前記回路は、主幹回路及び当該主幹回路から分岐した複数の分岐回路を含み、
    　前記電流検出部は、前記少なくとも２種類以上の出力の異なる変流器の信号線に接続する複数の接続端子をさらに備え、
    　前記複数の接続端子は、これら回路ごとに、隣接して配置される、ことを特徴とする請求項１に記載の電力計測器。     The circuit includes a master circuit and a plurality of branch circuits branched from the master circuit,
    The current detection unit further includes a plurality of connection terminals connected to signal lines of different current transformers of different outputs of the at least two types,
    The power measuring device according to claim 1, wherein the plurality of connection terminals are disposed adjacent to each other for each of the circuits.
  8. 　前記複数の接続端子は、出力の大きな前記変流器の信号線に接続するネジ端子、及び出力の小さな前記変流器の信号線に接続するコネクタ端子を含み、
    　前記変流器の信号線と接続されたプラグは、前記ネジ端子又は前記コネクタ端子の一方との接続を行うと、他方の接続端子を塞ぐ構造を有する、ことを特徴とする請求項７記載の電力計測器。     The plurality of connection terminals include a screw terminal connected to a signal line of the current transformer with a large output, and a connector terminal connected to a signal line of the current transformer of a small output;
    8. The plug according to claim 7, wherein the plug connected to the signal line of the current transformer has a structure for closing the other connection terminal when the plug terminal is connected to one of the screw terminal and the connector terminal. Power meter.
  9. 　前記電流検出部に備えられる２種類以上の負担抵抗は直列に接続され、
    　前記直列に接続された負担抵抗に接続される基準電位側の信号線を、グランドである０Ｖ以外の所定の基準電位に接続する、ことを特徴とする請求項１乃至８のいずれか一項に記載の電力計測器。     The two or more types of load resistors provided in the current detection unit are connected in series,
    9. The signal line on the reference potential side connected to the burden resistance connected in series is connected to a predetermined reference potential other than 0 V, which is a ground, according to any one of claims 1 to 8. Power meter as described.
  10. 　前記電力計測器は、多回路の電力計測が可能である、ことを特徴とする請求項１乃至８のいずれか一項に記載の電力計測器。 The power measuring device according to any one of claims 1 to 8, wherein the power measuring device can measure power of multiple circuits.
  11. 　前記電流検出部に備えられる２種類以上の負担抵抗は並列に接続され、
    　前記電流検出部は、前記並列に配置された負担抵抗の一端側に接続され、前記変流器の出力の電流経路を前記並列に接続された負担抵抗のいずれかの経路に切り替える回路切替器をさらに備え、
    　前記少なくとも２種類以上の出力の異なる変流器は、前記並列に接続された負担抵抗の両端側に接続される、ことを特徴とする請求項１に記載の電力計測器。     Two or more types of burden resistances provided in the current detection unit are connected in parallel,
    The current detection unit is connected to one end side of the load resistors arranged in parallel, and a circuit switcher that switches the current path of the output of the current transformer to any one of the load resistors connected in parallel. In addition,
    The power measuring instrument according to claim 1, wherein different current transformers of at least two or more types of outputs are connected to both ends of the burden resistance connected in parallel.
PCT/IB2012/001668 2011-08-31 2012-08-30 Electricity meter WO2013030655A1 (en)

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