JP4684022B2 - Electric energy metering method and electric energy metering device - Google Patents

Description

  The present invention relates to a power metering method and a power meter device, and more particularly, a power metering method capable of metering power using a single wattmeter regardless of the load current and rated voltage of an AC circuit, and The present invention relates to a power meter device used in the metering method.

  Currently, the watt-hour meter for measuring the amount of power in the AC circuit is a single watt-hour meter that can be directly connected to the AC circuit (hereinafter sometimes referred to as a single meter), and a meter installed in the AC circuit. There are two types of watt hour meters used in combination with transformers (hereinafter, sometimes referred to as transformer combination meters). Examples of the instrument transformer include an instrument current transformer (hereinafter sometimes referred to as CT) and an instrument transformer current transformer (hereinafter also referred to as VCT). The secondary output of these instrument transformers is configured to be introduced. Here, the VCT is an instrument transformer (hereinafter sometimes referred to as VT) and CT, which are stored in the same container.

  The two types of watt-hour meters are supposed to be properly used depending on the rated voltage of the AC circuit and the magnitude of the load current. This is because it is possible to measure the amount of power by connecting a single instrument directly to the current circuit in a low-voltage, small-current AC circuit, but in a high-voltage circuit or low-voltage, large-current circuit, a high voltage is directly applied to the single instrument. Or because a large current cannot flow. Normally, in a low voltage AC circuit with a rated voltage of less than 300 V, a single meter is used when the load (line) current is 120 A or less, and a CT combined watt hour meter is used when the load current exceeds 120 A. Further, in the case of an electric circuit with a rated voltage of 300 V or more, a watt hour meter combining VT and CT is used, and in a high piezoelectric circuit, a VCT in which these are integrated is generally used.

  The single instrument and the transformer combination instrument are different in the input method of the voltage signal and the current signal. That is, in the single meter, the distribution lines of the respective phases on the power supply side and the load side constituting the AC electric circuit are connected to predetermined terminals, respectively. For example, when a single meter is installed in a three-phase three-wire system or a single-phase three-wire circuit, a total of six wires, each of three wires on the power supply side and the load side, are connected to the terminal block of the meter. . This is because the two phases excluding the reference phase among the three phases on the power supply side are branched into two lines inside the meter, and each line is connected to the current circuit and the voltage circuit, respectively.

  On the other hand, in the transformer combination meter, when CT is used as the transformer, the secondary current and the line voltage of one or more CTs installed in the AC circuit are separately input to the watt hour meter, To the current circuit and the voltage circuit. For example, in a three-phase three-wire or single-phase three-wire AC circuit, CTs are installed in two phases excluding a predetermined reference phase, so the current line on the CT secondary side has two wires for each phase, a total of four wires. It is necessary to connect a total of seven wires, including three conductor wires individually connected to each of the three phases, to a predetermined terminal of the watt-hour meter main body. In the present specification, hereinafter, the term “reference phase” is used to mean a neutral line when it is composed of a voltage line and a neutral line such as a single-phase AC circuit, and in the case of a three-phase AC circuit. Any one phase is used for.

  Thus, even in the case of the AC circuit of the same electrical system, the CT combined instrument requires a 7-wire terminal with respect to the 6-wire terminal of a single instrument, and both cannot be used interchangeably. Therefore, the instrument manufacturer had to manufacture and stock a single instrument and a transformer combination instrument for each electrical system of the AC circuit.

  In addition, a watt hour meter for power trading must be periodically certified, and the watt hour meter needs to be replaced before being certified. In this case, there is no problem if a transformer is built in the watt hour meter in the transformer combination meter, but if the watt hour meter and the transformer are installed separately, the transformer and the watt hour meter Since it is necessary to connect an electric wire to each of the terminals individually, replacement work takes time, and there is a possibility that the connection will be wrong and the watt hour meter after replacement will not correctly measure the amount of power. Such a problem may occur more conspicuously when the installation place of the AC electric circuit and the watt hour meter are separated from each other.

  For the purpose of preventing the above-described erroneous connection and shortening the working time, for example, Patent Document 1 is a watt hour meter that measures the amount of power of a three-phase AC circuit, and a voltage input unit that inputs one specific line voltage; Current input means for inputting a specific two-phase line current of a three-phase AC circuit via a current transformer, virtual voltage conversion means for obtaining a virtual three-phase voltage from the specific line voltage, and the specific two-phase line current And the watt-hour meter provided with the electric energy calculation means which calculates | requires electric energy from the said specific line voltage and the said virtual three-phase voltage is proposed.

  However, the proposed watt-hour meter is based on the premise that the electric circuit is a balanced three-phase alternating current, and the number of connections to the terminal block is reduced by calculating the virtual three-phase voltage using the phase difference of each phase. Even if there is an advantage that the watt hour meter can be easily installed or replaced, it is limited to use in a three-phase three-wire AC circuit, and other electrical methods such as There is a problem that it cannot be used for a single-phase AC circuit such as a single-phase three-wire system. Therefore, even if it is the same three-wire AC circuit, in the case of a single phase, a watt hour meter must be prepared separately in addition to the one related to the above proposal. Each watt hour meter must be stocked every time.

JP 2000-266788 A

  In view of the above circumstances, the present invention makes it possible to measure the amount of electric power using a conventional single instrument regardless of the type of voltage of the AC circuit and the magnitude of the load current, and thus the versatility of the single instrument itself is thus achieved. By improving the system, it is possible not only to reduce costs on the part of the supplier, but also to measure energy easily and in a short time by preventing incorrect connections when installing or replacing electricity meters. It is an object to provide a method and a power meter device.

  As a result of intensive studies under the above-mentioned problems, the inventor alone supplied the AC circuit voltage to the current line on the secondary side of the current transformer or reduced the voltage of the circuit and supplied it alone. It has been found that the amount of electric power can be measured using a meter, and even when an electric circuit voltage is applied to the current line, dielectric breakdown of the current transformer does not occur, and the present invention has been completed.

  That is, according to one aspect of the present invention, the above-described problem is a current transformer in which one end of each conductor is connected to a phase conductor of each phase including a predetermined reference phase of an AC circuit, and a current line is provided on the secondary side. And separately connecting the other end of the conductor connected to the phase provided with the current transformer to the power supply side of the current line of the current transformer, This is achieved by an energy metering method characterized in that each line is introduced into a single energy meter together with a conductor having one end connected to the reference phase.

  In addition, according to another aspect of the present invention, the above object is achieved by the conductor having one end connected to the phase conductor of each phase including the predetermined reference phase of the AC circuit, and the remaining phases excluding the reference phase. And the other end of the conductor connected to each of the current transformer installation phases is connected to each of the current transformer installation phases. Achieved by a power meter that is connected to a power source side of a current line, and each of the current lines is introduced into a single watt hour meter together with a conductor having one end connected to the reference phase. Is done.

  The AC electric circuit to which the electric energy measuring method and the electric energy measuring device of the present invention can be applied is not particularly limited, and may be either single-phase or multi-phase, and is limited to the load current and rated voltage of the electric circuit. Not. Specifically, it can be applied to single-phase AC circuits such as single-phase two-wire systems and single-phase three-wire systems, and three-phase AC circuits such as three-phase three-wire systems and three-phase four-wire systems. It can be applied to the AC circuit. The number of lines (phase conductors) constituting the electric circuit is preferably large, and more preferably three or more.

  The conductor in the present invention is used to electrically connect a phase conductor of each phase and an electric device such as a watt hour meter. The conductor may be a conductive material having a predetermined capacity. Specifically, in addition to various electric wires with specifications that can withstand the rated current and short-circuit current of an AC circuit, a conductive metal fitting such as a bus bar may be used. It can be used suitably. Examples of the electric wires include bare wires such as hard copper, annealed copper, hard aluminum, heat-resistant aluminum, and steel core aluminum, and low-voltage and high-voltage insulated wires. Any of these conductors can be suitably used alone or in appropriate combination of two or more. When using the above electric wires, provide terminals at both ends, and when using conductive metal fittings, it can be easily connected to various conductors and electrical equipment in addition to the distribution wires of the above phases. Are preferably provided at both ends.

  The CT in the present invention is installed in each phase excluding the reference phase in a single-phase or multi-phase AC circuit by a conventionally known method. Generally, there are a through type and a wound type in CT, and any type can be used in the present invention.

The through-type CT has an annular magnetic core having a through-hole at substantially the center and a secondary winding wound around this, and these are usually housed in a casing. The through-type CT may be a type in which a phase conductor such as a distribution line is directly inserted into the through hole or wound around an annular magnetic core when installed in an AC circuit, or a power supply side distribution line and a load side distribution line are connected in advance. Conductors such as various types of electric wires, such as hard copper wires each having a possible terminal at both ends, and conductive metal fittings such as bus bars (hereinafter, the conductor having terminals at both ends are referred to as primary conductor pieces) are inserted into the through holes. Alternatively, it may be fixed in a state where it is wound around an annular magnetic core, and a phase body is connected to the terminal. In the case of the former type, there are a divided type in which the annular magnetic core can be divided and a non-divided type in which the annular magnetic core cannot be divided. In the winding CT, an annular magnetic core around which a primary winding and a secondary winding having terminals at both ends are wound is housed in a casing, and the primary and secondary terminals are placed on the outer surface thereof. Are arranged. In this type of CT, phase conductors such as power supply side and load side distribution lines are connected to the primary side terminal. Among these CTs, in the present invention, it is preferable to use a penetration type CT or a winding type CT provided with a primary conductor piece.
In the present specification, the term “phase conductor” is used to include the above-mentioned primary conductor piece and primary winding connected in series to the distribution line in addition to the distribution line. In addition, the term “current line” includes an output line drawn from both ends of the secondary winding (excluding the winding portion wound around the annular magnetic core), and is introduced into the current circuit of a single instrument. The round trip path returning from the secondary winding to the secondary winding is referred to as the forward path side (k pole side), particularly the “power supply side”.

  In the present invention, one end of each of the exemplified conductors is connected to the phase conductor of each phase of the AC circuit. The connection position can be set arbitrarily, but considering the labor in connection work, etc., terminals provided on each phase conductor, for example, terminals provided on the periphery of these, in addition to terminals provided on CT and single instruments, etc. It is preferable to connect to each other using a predetermined fixing tool. Further, when the phase conductor is a conductive metal fitting or the like, the conductor may be fixed at an appropriate position using a conventionally known method.

  When the rated voltage of the AC circuit to measure the amount of electric power is high (in the current regulations, 300 V or more), an instrument transformer (VT) is installed in the middle of the conductor, and the conductor is connected to the conductor via the VT. It can be connected to the power supply side of each CT secondary current line. The connection of the VT in the middle of the conductor can be performed by a known method. Regardless of single-phase or multi-phase, in the case of a three-wire circuit, two VTs are prepared, and the load side of the secondary winding can be connected together with the primary winding of each VT to be common Good. In this case, a conductor from the reference phase of the AC circuit is connected to the common primary winding. Further, one end of a conductor prepared separately is connected to the load side of the common secondary winding, and the other end of the conductor is introduced into a predetermined terminal of the single meter. The VT can be installed in the AC circuit separately from the CT. However, particularly in the case of a high-voltage circuit, the VT may be installed in the circuit as a VCT connected to the CT and housed in the same vessel. The combination of VT and CT and VCT may be appropriately selected depending on whether the rated voltage of the AC circuit is higher than a predetermined value or high voltage. Thus, by using a combination of CT and VT or VCT, both the voltage and current of the AC circuit can be transformed into a small force, and as a result, it can be supplied to a single instrument regardless of the rated voltage of the circuit. There are advantages.

  As described above, the conductor whose one end is connected to the phase conductor is connected to the power source side of the current line on the CT secondary side at the other end. When a VT is installed in the middle of the conductor, the other end of the conductor having one end connected to the VT secondary side is connected to the power supply side of the current line. The connection position between the conductor and the current line is not particularly limited, and may be, for example, inside the CT case or in the middle of the current line from the CT case to the single instrument. In the former case, the other end of the conductor is connected to the output line of the secondary winding (when the current line connection terminal is provided in the casing) in the casing in which at least the secondary winding and the annular magnetic core are housed. Can be connected to the power source side of the terminal. Specifically, if CT is a through-type, the other end of the conductor having one end connected to an appropriate position of the primary conductor piece is drawn into the housing and connected to the power supply side of the output line. Good. In the case of a wound type CT, since the primary winding and the secondary winding are stored in advance in the CT housing, the other end of the conductor is connected in advance to the power supply side of the output line of the secondary winding. In addition to being able to do so, it is possible to electrically connect an appropriate position of the primary winding to the power supply side of the output line of the secondary winding by the conductor in the housing. Thus, by connecting the conductor in the CT in advance and storing it, the conductor connection work on the current transformer side becomes unnecessary, and the number of connection lines can be reduced, so that the occurrence of erroneous connection can be suppressed in advance. In the latter case, the other end of the conductor is connected to a current line connection terminal provided on the outer surface of the CT housing or a predetermined connection terminal of a single meter.

  The single watt-hour meter main body used in the watt-hour meter of the present invention may be provided with various signal output functions such as a pulse transmission function regardless of whether it is an electronic type or an induction type. Further, the CT, VT, or VCT may be accommodated inside the single watt hour meter.

  According to the present invention, the conductor connected to each phase except the reference phase is connected to the power source side of the CT current line directly or via an instrument transformer, and the voltage is reliably supplied to the watt hour meter through the current line. Therefore, the secondary output of the instrument transformer installed in the AC circuit can be introduced into a single instrument to measure the amount of power in the AC circuit, and there is no need to use a single instrument and a transformer combination instrument separately. Further, since the secondary output of the instrument transformer is used, the single instrument can be used for a low voltage regardless of whether the AC circuit is at a low voltage or a high voltage. Therefore, if the electrical system of the AC circuit is the same, one type of single instrument can be used regardless of the rated voltage or load current of the AC circuit, and as a result, the versatility of the single instrument can be improved, and the instrument manufacturer Can reduce production varieties and facilitate inventory management, thereby reducing costs.

  In the present invention, a single meter can be used as a watt-hour meter, and the number of connections can be reduced as compared with a conventional transformer combination meter.Therefore, the possibility of preventing misconnection during the installation and replacement of a watt-hour meter is reduced. The In addition, by using the power meter of the present invention, the number of connections to a single meter can be reduced as compared with the case of conventional power meter using a single meter. I can plan.

  Hereinafter, an electric energy measuring method and an electric energy measuring device according to the present invention will be described in more detail with reference to the drawings. FIG. 1 is a connection diagram of a power meter of the present invention installed in a low-voltage single-phase three-wire AC circuit with a load current of 150 A or less. In this single-phase three-wire AC circuit, the phase P2 is a reference phase (neutral wire). In this figure, open circles represent terminals. The electric system of the AC electric circuit shown in FIG. 1 may be a low-voltage three-phase three-wire system because the connection method and the internal structure of the power meter are substantially the same.

  As shown in FIG. 1, the two CTs 11 and 13 are installed on the voltage lines P1 and P3 of each phase excluding the reference phase P2. The two CTs are each provided with primary conductor pieces 12 and 14, and terminals 121, 141 and 122, 142 are provided at the ends of the power supply side and the load side, respectively. Power supply side distribution lines (phase conductors) P1 and P3 are connected to the power supply side terminals 121 and 141 of the primary conductor pieces 12 and 14, respectively, and load side distribution lines (phase conductors) are connected to the load side terminals 122 and 142, respectively. P1 and P3 are connected to each other.

  On the secondary side of the CTs 11 and 13, external terminals 1S (power supply side. Generally referred to as a k-pole terminal. The same applies hereinafter) 1L (load side. Generally referred to as an L-pole terminal) provided on the outer surface of the CT casing. The same shall apply hereinafter.) And 3S (power supply side terminal) and 3L (load side terminal) are connected to one end of current lines 15 (power supply side) and 16 (load side) and current lines 17 (power supply side) and 18 (load side), respectively. The other ends of these current lines are connected to the terminals 1S, 1L, 3S and 3L of the watt-hour meter 10, respectively. Thus, the secondary current modified to a small current in proportion to the load current flowing in each phase flows through the current lines 15 and 17 on the power source side, and is input to the current circuit of the single meter 10. A secondary circuit of each CT that feeds back through is formed. The L pole in the parenthesis should originally use lower case letters, but for convenience, upper case letters are used to prevent confusion with the number 1.

  In the present invention, as shown in FIG. 1, the conductor 21 having one end connected to the power supply side terminal 121 of the primary conductor piece 12 of the CT11 is connected to the power supply side terminal 1S of the current line 15 of the CT11, and CT13 The conductor 22 having one end connected to the power supply side terminal 141 of the primary conductor piece 14 is connected to the power supply side terminal 3S of the current line of CT13. These conductors 21 and 22 may be connected in advance between the predetermined terminals, or may be connected at the time of CT installation.

  A line voltage of the AC circuit is applied between the current lines 15 and 17 and a conductor 20 having one end connected to a terminal 19 provided in the middle of the phase P2 (reference phase). Thus, the conductors 21 and 22 having one end connected to each of the phases provided with the CT are connected to the current lines 15 and 17 of the CTs 11 and 13 respectively, and the phase P2 together with the current lines 15, 16 and 17 and 18 are connected. By introducing the conductor 20 connected to the appropriate connection point 19 into the single meter 10, the amount of power in the AC circuit can be measured.

  In the present embodiment, the CT 11 and 13 are installed on the AC circuit, and the secondary output is used for measuring the electric energy. It is only necessary to connect a total of five wires including four current lines and one conductor line connected to the reference phase. Therefore, it is possible to prevent erroneous connection to the watt hour meter body and to shorten the working time.

  FIG. 2 is a connection diagram of the electric energy meter of the present invention installed in the high-voltage AC circuit. In this figure, AC electric circuits P1, P2 and P3 are single-phase three-wire AC electric circuits as in the above embodiment. A VCT 30 is installed in the AC circuit, and power supply side connection terminals P11, P21 and P31 and load side connection terminals P12, P22 and P32 provided on the outer surface of the casing are respectively connected to phase conductors on the power supply side of each phase (distribution lines). ) And the load-side phase conductor (distribution line).

  In this VCT 30, CTs 31 and 32 are connected in series to the phase P1 and the phase P3, respectively, and conductors 38, 39 and 40 each having one end connected to the phase conductor of each phase are connected to the primary side of the VT 33. Yes. On the secondary side of the CT 31, current lines 34 (power supply side) and 35 (load side) are provided, and these are connected to the external connection terminals 1S and 1L of the VCT, respectively. Similarly to CT31, CT32 also has current lines 36 (power supply side) and 37 (load side) on its secondary side, which are connected to external terminals 3S and 3L of the VCT, respectively. From the secondary side of the VT 33, the conductor 42 corresponding to the phase (reference phase) P2 is directly connected to the external terminal 2S, and the conductors 41 and 43 corresponding to the phases P1 and P3 are respectively connected to the power supply side of the CTs 31 and 32. Connected to current lines 34 and 36.

  The signal lines 15, 16, 17, 18 and 20 connected to the external terminals 1S, 2S, 3S, 3L and 1L of the VCT are predetermined terminals of the terminal block of the watt-hour meter 10 corresponding to the external terminals of the VCT 30, respectively. Connected to 1S, 2S, 3S, 3L and 1L. The conductor 20 from the external terminal 2S of the VCT is grounded by a ground wire 25 as shown in FIG.

  When this AC circuit is energized with the above configuration, the line voltages between the conductors 38, 39 and 39, 40 respectively connected to each phase are stepped down at the VT 33, respectively, and the secondary side conductors 41, 42 are connected. And a secondary voltage (usually 110V) is applied between the current lines 34 and 36 on the power source side of the CTs 31 and 32 and the conductor 42 from the neutral line by the conductors 41 and 43. The On the other hand, secondary currents flow through the power supply sides 34 and 36 of the current lines of the CTs 31 and 32, respectively. By introducing these current lines 34 to 37 and the conductor 42 from the external terminal of the VCT to the single meter 10 via the signal lines 15, 16, 17, 18 and 20, it is possible to measure the amount of electric power in this AC circuit. . Moreover, since the current signal (normally maximum 5 A) and voltage signal (normally maximum 110 V) transformed into a small force by the VCT 30 as described above are input to the single meter, even if the AC circuit is high voltage, A single watt hour meter can be used. Furthermore, in the present embodiment, the number of connections to the watt hour meter main body is 5 as in the above embodiment, so that the occurrence of erroneous connections is suppressed and the working time is shortened.

  The embodiment of the present invention has been described above for the AC single-phase three-wire circuit and the AC three-phase three-wire circuit. However, the power amount measuring method and the power amount of the present invention are similarly applied to the case of the single-phase two-wire circuit. A weighing device can be applied. That is, in the case of the electric circuit, since it is composed of a voltage line and a neutral line, one end of a conductor is connected to each of these two lines, and a CT is installed on the voltage line. Thereafter, the other end of the conductor is connected to the power source side of the current line on the CT secondary side. By introducing a conductor connected to the neutral wire together with the two current lines into a single meter (four-wire terminal) for a single-phase two-wire electric circuit, the energy metering device of the present invention is formed. Weighing is possible. In this case, it is only necessary to connect a total of three conductors from the current line and the neutral line to the single meter.

  In addition, in the case of a three-phase four-wire AC circuit, it is composed of three voltage lines and one neutral line, and normally, CTs are individually installed on the three voltage lines. In this case, a conductor having one end connected to the voltage line is connected to the power supply side of each CT secondary current line installed in each of the three voltage lines, and each CT current line and the reference phase ( By introducing a conductor having one end connected to the neutral wire) into a single meter, it is possible to measure the amount of power in the AC circuit. The single instrument used in this case is provided with a 10-wire terminal, but in the present invention, 7 wires may be connected. Since the number of connections can be reduced in this way, the risk of erroneous connection is reduced and the working time is shortened. In addition, as a single meter used for the alternating current circuit in this case, three single-phase two-wire single watt-hour meters can be used in addition to the above single meter.

  FIG. 3 is a partial longitudinal sectional view of a through-type current transformer used in the power metering device of the present invention as seen from the side. In this figure, in order to simplify the description, only the necessary configuration inside the CT 50 is schematically illustrated, and constituent members such as an insulating material and a supporting material are omitted. As shown in FIG. 3, the CT 50 houses an annular magnetic core 52 and a secondary winding 53 wound around the casing 51 in a casing 51. Output lines 531 and 532 at both ends of the secondary winding 53 are respectively connected to output terminals 54 and 55 provided on the outer surface of the casing 51. One end of a current line (power supply side) 531 and a current line (load side) 532 is connected to each of the output terminals 54 and 55, and the other end thereof is connected to a predetermined terminal of a single watt hour meter (not shown). The

  The through hole 521 provided at the approximate center of the annular magnetic core 52 is fixed by covers 62 and 62 that close the through hole 521 from both ends in a state where the coated hard copper wire 60 as the primary conductor piece passes through the approximate center. Connection terminals 61 and 61 are fixed to both ends of the coated hard copper wire 60, respectively, and these terminals are connected to a distribution line on the power supply side and load side (not shown). The coated hard copper wire 60 may be a conductive metal fitting such as a bus bar. The coated hard copper wire 60 and the output line 531 on the power source side are electrically connected by a conductor 70. The connection between the coated hard copper wire 60 of the conductor 70 and the output line 531 on the power source side can be performed by a conventionally known method. In addition, in FIG. 3, although the penetration type is illustrated as a current transformer, a winding type may be sufficient. In the figure, the conductor 70 is housed in the housing 51. However, as described above, the terminal 61 and the output terminal 54 may be electrically connected by the conductor 70.

  By energizing the coated hard copper wire 60, the annular magnetic core 52 is excited, and a secondary current transformed into a small force in proportion to the load current flowing through the coated hard copper wire 60 by the mutual induction action is generated in the secondary winding 53. Flowing into. This secondary current is sent to a single meter (not shown) through a current line 531 through an output terminal, and is fed back by a current line 532 through a current circuit of a single meter (not shown). In this case, since the coated hard copper wire 60 and the current line 531 on the power source side are connected by the conductor 70, the line voltage between the coated hard copper wire 60 and a reference phase (not shown) in the AC circuit is reduced. A corresponding voltage is applied to the current line 531 on the power supply side. Thus, even if a voltage is applied to the current line 531, there is no problem in terms of the dielectric strength of CT, and by applying a voltage to the current line 531, the amount of power can be measured by a single meter. Further, since the CT can connect the primary conductor piece and the current line in advance by a conductor, the amount of electric power can be obtained by simply connecting the current line and the conductor connected to the reference phase to the watt hour meter. In addition to being able to measure the power, it is also possible to connect the watt hour meter and a denaturing instrument for measuring instruments such as CT in advance, so that the problem of misconnection can be solved reliably and the working time can be shortened. Figured.

  As described above, by using the power metering method and power meter device of the present invention, regardless of the rated voltage and load current of the AC circuit, regardless of single-phase or multi-phase, various electrical systems can be used. It is possible to measure the amount of power using a conventional single meter adapted to the number of lines (number of phase conductors) constituting the AC circuit. Therefore, unlike the prior art, a dedicated watt-hour meter used in combination with a meter transformer is not required, and the versatility of a single meter can be improved. Also, the instrument transformer used in the electric energy meter of the present invention sets the CT ratio and VT ratio so that the secondary current is 5A for CT and the secondary voltage is 110V for VT. In general, according to the present invention, a conventional single instrument for low voltage and small current can be used in common for a high voltage AC circuit or a low voltage large current AC circuit. There are advantages. As a result, it is not necessary for the supplier to stock various watt-hour meter bodies as in the prior art, which not only facilitates inventory management but also significantly reduces manufacturing costs.

Further, according to the present invention, since the number of connections to the watt hour meter can be reduced as described above, there is no problem of an abnormal measurement value due to incorrect connection in the installation and replacement work of the watt hour meter. Time can also be shortened.

  The electric energy metering method and the electric energy meter device according to the present invention can be applied to various AC electric circuits leading to general households and factories. Since the metering accuracy of a single meter has been remarkably improved, the power metering device of the present invention may be used for power trading by passing the test based on the metering method.

It is a connection diagram of one embodiment of the electric energy metering device of the present invention. It is a connection diagram of another embodiment of the electric energy metering device of the present invention. It is a partial longitudinal cross-sectional view of the side surface of the current transformer used in combination with the electric energy metering device of the present invention.

Explanation of symbols

P1, P2, P3 AC circuit (P2 is the reference phase)
10 Single energy meter 11, 13 CT
15, 16, 17, 18 Current line 21, 22 Conductor 30 VCT
31, 32 CT
33 VT
41, 43 Conductor 51 CT housing 52 Ring magnet 521 Through hole 53 Secondary winding

Claims (11)

  One end of each conductor is connected to the phase conductor of each phase including a predetermined reference phase of the AC circuit, and a current transformer having a current line on the secondary side is individually installed in the remaining phases excluding the reference phase. The other ends of the conductors connected to the phase provided with the current transformer are respectively connected to the power supply side of the current line of the current transformer, and then each of the current lines is alone with the conductor connected to the reference phase at one end. An electric energy metering method characterized by being introduced into an electric energy meter. The electric power metering method according to claim 1, wherein the AC electric circuit includes three or more wires.   In the middle of the conductors connected to the phase conductors of each phase including the predetermined reference phase of the AC circuit, an instrument transformer capable of transforming and outputting the line voltage between the phases is installed, and the reference phase is Separately install a current transformer with a current line on the secondary side in the remaining phase, and connect the other end of the conductor drawn from each of the phases with the current transformer on the secondary side of the instrument transformer. After connecting to the power supply side of the current line of the said current transformer, each of the said current line is introduce | transduced into the independent watt-hour meter with the conductor which connected the end to the said reference phase. The potential transformer is a power amount measuring method according to claim 3 wherein those housed in the same vessel body with current transformers. The method of measuring electric energy according to claim 3 or 4 , wherein the AC electric circuit comprises three or more wires.   A current transformer having one end connected to a phase conductor of each phase including a predetermined reference phase of an AC circuit, and a current line on the secondary side separately installed on the remaining phases excluding the reference phase And the other end of the conductor connected to each of the current transformer installation phases is connected to the power supply side of the current line of the current transformer, and each of the current lines Is introduced into a single watt hour meter together with a conductor having one end connected to the reference phase. The conductor of each current transformer installation phase has one end connected to the phase conductor of each phase in the current transformer and the other end connected to the power supply side of the current line of the current transformer. The electric energy metering device according to 6. The electric energy meter according to claim 6 or 7, wherein the AC electric circuit is composed of three or more wires. A conductor having one end connected to a phase conductor of each phase including a predetermined reference phase of the AC circuit;
A transformer for an instrument that is connected to the primary side at the other end of each of the conductors, transforms a line voltage between the phases, and can output through the conductors connected at one end to the secondary side;
A current transformer installed separately for each of the remaining phases except the reference phase and having a current line on the secondary side;
It consists of a single watt hour meter body,
The other end of each phase conductor on which the current transformer is installed on the secondary side of the instrument transformer is connected to the power supply side of the current line of the current transformer, and each of the current lines is for the instrument. An electric energy meter characterized by being introduced into a single watt hour meter together with a conductor corresponding to a reference phase on the secondary side of a transformer. The instrument transformer is the one in which are accommodated in the same vessel body with current transformer electric energy metering device according to claim 9. The AC circuit is electric energy metering device according to claim 9 or 10 composed of three or more lines.

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