JP2008014773A - Voltage/current transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voltage/current transformer capable of heightening efficiency of a work by reducing a load of an operator by simplifying connection when being installed in an AC cable run, and facilitating exchange or maintenance of apparatuses. <P>SOLUTION: In this voltage/current transformer, an outer casing provided with at least an openable/closable opening includes a group of primary-side connection conductors equipped with a pair of primary-side terminals capable of connecting respectively each phase conductor on the power source side and on the load side of each phase of the AC cable run, a CT connectable in series to the primary-side connection conductor having the same phase as each phase excluding a reference phase of the AC cable run, a VT connectable in parallel to the primary-side connection conductor, and a group of secondary-side connection conductors connectable to the CT and the VT and sending each output therefrom to a secondary-side output terminal. The transformer has a characteristic wherein the CT and the VT are stored detachably through the opening. Preferably, the CT is equipped with the primary terminal, and the VT is a three-phase VT. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention enables VT and CT to be detachably accommodated, thereby facilitating the replacement and maintenance of these devices and increasing the efficiency of wiring work when installed on an AC circuit. The present invention relates to a current transformer.

  In a low-voltage AC circuit with a nominal voltage of 200 V or less, the electric energy is usually measured by directly connecting a single watt hour meter (hereinafter, also referred to as a single meter) having a predetermined specification to the circuit. In the case of an AC circuit that exceeds the above, an instrument transformer (hereinafter referred to as VT) and a current transformer (hereinafter referred to as CT) are installed in the AC circuit, respectively, so that the voltage and current of the circuit are reduced to a low voltage and small. Electric power is measured by transforming it into current and outputting it, and introducing each output into a transformer combined watt-hour meter (hereinafter sometimes referred to as transformer combined meter).

  FIG. 6 shows a connection diagram in the case of measuring the electric energy of the low-voltage three-phase three-wire AC circuit using VT and CT. In this figure, the load side device 101 is supplied with electric power from the power source side device 100 by the phase conductors of the U, V, and W phases connecting the load side device 101 and the power source side device 100. CT phase 20a and CT 20b are respectively installed in the middle of the U-phase and W-phase phase conductors, and U-phase and W-phase phase conductors are connected in series to both ends of the primary winding of these CTs from the power supply side and the load side, respectively. Connected to. Further, the secondary output lines 21 and 22 of the CT 20a and the secondary output lines 23 and 24 of the CT 20b are respectively connected to predetermined connection terminals 51 of the transformer combination meter 50 and flow through the U-phase and W-phase conductors. The current is transformed into a small current proportional to the current flowing through each phase conductor by each CT, and the small current is output to the combination meter 50.

  In addition, three branch lines 11c, 12c, and 13c are branched from the phase conductors of the U, V, and W phases of the AC circuit, respectively, and further, the branch line 14 is branched from the branch line 12c. Branch lines 11c, 12c and 14, 13c are connected to primary terminals of two single-phase VTs 30a and 30b, respectively. In this way, by connecting one VT in parallel between the U phase, the V phase, and between the V phase and the W phase, the interphase voltage between these two phases is input to each of the two VTs, where It is transformed into a proportional low voltage and output to the transformer combination meter 50. In response to the small current and low voltage inputs, the transformer combination meter measures the amount of power in the AC circuit.

  However, if VT and CT are separately installed in the AC circuit in this way and the primary side and secondary side are connected, wiring becomes very complicated, and not only erroneous connection is likely to occur, but also wiring work There are also problems such as reduced efficiency and longer work time. Also, the installation locations of VT and CT are usually different, and in many cases, multi-core cables for instruments cannot be used, so wiring is performed individually by the operator's ingenuity, and for each installation location of these instruments A situation occurs in which the wiring method is different.

In order to solve such a problem, for example, Patent Document 1 includes a current transformer that is attached to two phases of an AC circuit, and a cable that connects the current transformer and a current input unit of a power meter. Discloses a power metering device that uses a single connector integrated with a connection for connecting the current transformer attached to two phases to the cable.
JP 2003-177146 A

  In view of the circumstances described above, the present invention reduces the burden on the operator by simplifying the connection when installed on the AC electric circuit, thereby improving work efficiency, and facilitates replacement and maintenance inspection of these devices. An object of the present invention is to provide a voltage / current transformer.

  As a result of intensive studies, the inventor has one primary terminal that connects the power-side phase conductor and the load-side phase conductor, and a secondary-side output terminal that is connected to an external electrical device. In the outer box, CT and VT are detachably accommodated and arranged in advance so that the primary and secondary terminals can be connected to the primary and secondary terminals of CT and VT in advance. By laying down, it was found that the complicated wiring work as described above is unnecessary and the object can be achieved, and the present invention has been completed.

  That is, according to the present invention, a pair of primary sides capable of connecting the power source side and the load side phase conductors of each phase of the AC circuit are provided in the outer box provided with at least an openable / closable opening. A group of primary side connection conductors having terminals, a CT that can be connected in series to the primary side connection conductor that is in phase with each phase except the reference phase of the AC circuit, and parallel to the primary side connection conductor And a group of secondary-side connection conductors that are connectable to the CT and the VT and send outputs from these to the secondary-side output terminal, and the CT and the VT are It is achieved by a voltage / current transformer that is detachably accommodated through the opening.

  The CT and the VT are respectively accommodated in predetermined spaces in the outer box through the openings. This space only needs to have a volume capable of accommodating both of these devices, and the surroundings may or may not be partitioned by a partition wall. Whether or not to provide this partition wall can be appropriately determined in consideration of the voltage of the AC circuit, the load current, and the like.

  In the case where a partition wall is provided around the box, a storage box for storing CT and VT is thereby formed. This storage box may store one each of CT and VT, or may be configured to store CT and VT together by increasing the volume. When a plurality of CTs or VTs or both of them are accommodated, an accommodation box that accommodates CTs and VTs together may be installed. Among these, it is preferable to provide a storage box for storing one CT and one VT. In the present specification, hereinafter, a storage box for storing a CT is referred to as a “CT storage box”, and a storage box for storing a VT is referred to as a “VT storage box”.

  The CT storage box and the VT storage box are not particularly limited as long as the CT and VT can be stored through the openable and closable openings provided in the outer box, respectively, but preferably the upper edge of the peripheral wall of the storage box is the outer box. It is good to be inscribed in the peripheral area | region of the provided opening. By providing the storage box in this way, it is easier to put in and out CT and VT, and maintenance and inspection of these devices is also facilitated.

  From the viewpoint of further improving the workability when accommodating or taking out CT and VT in the storage box, the primary connection conductor is drawn in such a manner that its tip region protrudes into each storage box, and the CT or It is preferable that the primary terminal of the VT can be brought into contact with or directly connected to the primary terminal of the VT. Similarly, the tip end region of the secondary connection conductor protrudes into the storage box and is brought into contact with the secondary terminal of the CT or the VT directly or via a connection means. It is preferable that it is a thing.

  In the voltage / current transformer of the present invention, the secondary connection conductor connected to the power supply side of the secondary terminal of the CT, and the secondary connection conductor of the VT that is in phase with the phase where the CT is installed, Can be connected. By connecting the VT and CT secondary connection conductors in this way, the number of secondary output lines from the voltage / current transformer of the present invention can be further reduced. Moreover, by this, when measuring the electric energy of an AC circuit using the voltage current transformer of this invention, for example, a single meter can be connected to the secondary output terminal of the said measure, using VT and CT, and electric energy There is an advantage that it can contribute to the unification of the total types.

  The CT and VT of the present invention need not be specially machined, and can be those normally used. Preferably, the CT has a primary terminal in order to facilitate these connections in the outer box. Specifically, a wire-wound CT or a through-type CT provided with a primary conductor piece can be used. Further, for the VT, it is preferable to use a three-phase VT in order to further simplify the wiring to these.

  According to the voltage / current transformer of the present invention, the group of primary side connection conductors, CT, VT, and the group of secondary side connection conductors that send output from these devices to the secondary side output terminal are externally connected. Since it is integrated in the box, it is only necessary to connect the phase conductor of each phase of the AC circuit and the output line to the primary side connection terminal and secondary side output terminal, respectively, so that the connection can be simplified. As a result, the burden on the operator is reduced and the work efficiency is improved, and the CT and the VT are detachably accommodated through the opening provided in the outer box, so that the replacement of the equipment and the maintenance inspection are facilitated. .

  In addition, since it is not necessary to apply special processing to the outer shape of the CT or VT and the normal product can be used as it is, maintenance and replacement of these devices can be facilitated.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The AC circuit shown in the following diagram is a three-phase three-wire system composed of U, V, and W phases, and the V phase is assumed to be the reference phase of the circuit. In this specification, the term “reference phase” is used in the following description to mean a neutral line when a voltage line and a neutral line, such as a single-phase AC circuit, are used. In some cases, it will be used in the meaning of any one phase. 1 and 4, the front side is “up” or “upward” and the back side is “down” or “down” toward the drawings.

  FIG. 1 is a plan sectional view schematically showing an outline of one embodiment of a voltage / current transformer of the present invention. As shown in this figure, the voltage / current transformer 1 of the present embodiment has a structure in which CT housing boxes 2 and 3 and a VT housing box 4 are arranged and fixed in an outer box 10. In both the storage boxes, CT20, 21 and VT30 are stored, respectively. Further, in the voltage / current transformer 1 of the present invention, the groups 11 to 13 of the primary side connection conductors for connecting the CT and VT and the AC circuit, and the respective devices and the secondary side output terminals ( A group of secondary side connecting conductors 22 to 25, 35, 36, and 38 that connect the base 17) are arranged.

  The outer box 10 is a container having a capacity that can completely accommodate each of the above-described devices inside and that can lay a group of primary and secondary connection conductors. The outer shape is not particularly limited, and is usually a cube or a rectangular parallelepiped. In addition, the outer box 10 is generally composed of a plate body made of metal such as iron or steel, wooden or plastic. When the outer box 10 is formed of a metal plate, the outer box 10 is preferably grounded by a known grounding means and a grounding method.

  As shown in FIG. 1, the outer box 10 has openings 2 a, 3 a, 4 a that can be opened and closed above the CT storage boxes 2, 3 and the VT storage box 4. These openings are not particularly limited as long as these devices can be taken in and out in consideration of the ease of maintenance and inspection of CT or VT, but preferably the legs of CT20, 21 and VT30, respectively. It is preferable that the size is such that the part can be accommodated as it is with the part facing down (back side as viewed in the drawing).

  The primary side connection conductors 11 to 13 are respectively drawn out from the side walls on both sides of the outer box 10, and a pair of primary side terminals 11a, 11b; 12a for each phase of the AC circuit are provided at both ends of these primary side connection conductors. 12b; 13a and 13b are provided. One primary side terminal (11a, 12a, 13a) of each pair is connected to the power source side phase conductors of the U, V, W phases of the AC circuit, respectively, and the other primary side terminal (11b). , 12b, 13b) are connected to load-side phase conductors U1, V1, W1, respectively. In FIG. 1, each pair of primary terminals provided on the outer box 10 is provided so as to protrude from the surface of the outer wall of the outer box 10. However, the present invention is not limited to this mode, and an electric shock or the like does not occur. Thus, it can be provided in various modes. These primary side terminals can also be provided, for example, at a position close to the vessel wall inside the outer box 10. In this case, an opening that can be opened and closed is further provided in the wall of the outer box 10, and the power supply side and load side phase conductors may be connected with the opening opened.

  The primary side connection conductors 11 to 13 may be any conductive material having a predetermined capacity corresponding to the current flowing through the AC circuit, for example, various electric wires having specifications that can withstand the rated current and short-circuit current of the AC circuit. A conductive metal fitting such as a bus bar or a flexible conductive band can be suitably used. Specific examples of the electric wires include bare wires such as hard copper, soft copper, hard aluminum, heat-resistant aluminum, and steel core aluminum, and low-voltage and high-voltage insulated wires. These electric wires and conductive metal fittings can be appropriately selected in consideration of the voltage and load current of the AC circuit, and any of them can be used alone or in combination of two or more. For example, a bus bar can be laid between the primary side connection terminal and the storage box of each device, and a flexible conductor connected to the load side end of the bus bar can be drawn into each storage box. .

  Each of the CT storage boxes 2 and 3 and the VT storage box 4 has a partition shape and is formed in a box shape, and these external shapes can be appropriately set in consideration of the shape of the CT and VT to be stored. It is preferable that the outer shape of the outer box is a rectangular parallelepiped or a cube. The upper end edges of the peripheral walls (partition walls) of the storage boxes 2, 3, 4 are fixed in contact with the peripheral walls of the openable / closable openings 2 a, 3 a, 4 a provided in the outer box 10. . The fixing method is not particularly limited, and can be appropriately selected from known methods. In FIG. 1, one CT or VT is accommodated in one accommodation box, but the present invention is not limited to this.

  The CT storage boxes 2 and 3 are respectively arranged between the U-phase and W-phase primary connection conductors 11 and 13. The primary side connection conductors 11 are respectively laid from the power supply side 11a and the load side 11b of the primary side terminals, and their tips are drawn through through holes (not shown) of the opposing partition walls of the CT storage box 2, And are arranged to face each other with a predetermined gap. Similarly, the primary side connection conductor 13 is also drawn into the inside through the partition wall facing the CT storage box 3 from the power supply side 13a and the load side 13b of the primary side terminal. CT20 and 21 are stored in each gap.

  CTs 20 and 21 usually have the same current transformation ratio and can be suitably used as long as they are normally used for current measurement or the like, but those having a primary terminal are preferable. As CT provided with such a primary terminal, various electric wires such as hard copper wires and conductive metal fittings such as bus bars (hereinafter, the electric wires or conductive metal fittings are referred to as “primary conductor pieces”) are through holes. A through-type CT or a wound-type CT inserted into or wound around is used. In the present embodiment, as shown in FIG. 1, the primary terminals of the CT are provided so as to protrude substantially horizontally in a direction away from the casing, but the position of the primary terminals is not limited to this.

  The gap has a relatively large current transformation ratio and a large housing size because the size of the housing does not change greatly even if the current transformation ratio is different within a predetermined current range, especially when the CT is for low pressure. By setting the gap according to the total length, it is possible to accommodate CT with a smaller casing and a smaller current transformation ratio. If necessary, a long hole penetrating the front and back in the longitudinal direction is formed near the end of the primary side connecting conductor arranged opposite to each other, or the primary side connecting conductor as described above. It is also possible to cope with the case where the position of the fastener insertion hole of the primary terminal of the CT is changed by using a flexible conductive band or various electric wires for the portion drawn into each storage box.

  In addition, the height from the bottom surface of the lower surface of the primary connection conductor 11 facing each other in the CT storage boxes 2 and 3 is appropriately set so as to be equal to or higher than the height from the lowest end of the CT housing leg to the primary terminal. can do. The height from the bottom surface of the lower surface of the primary side connection conductor 11 is also preferably adjusted to the height of a relatively large current transformation ratio and a large housing size. When accommodating a small CT with a small current transformation ratio, this CT is supported by the primary-side connecting conductors arranged opposite to each other, and if necessary, the CT leg and bottom surface of the CT are supported. A spacer having a necessary thickness can be inserted and fixed in between.

  In the state in which CTs 20 and 21 are accommodated in the CT storage boxes 2 and 3, respectively, as shown in FIG. Are brought into contact with the upper surfaces of the primary side connection conductors 11 and 13 on the power source side and the load side drawn in to be overlapped with the primary side connection conductors. If they do not overlap, they can be connected using connection means (not shown) such as a connection piece of a predetermined size. As the connection piece, for example, the above-described conductive metal fitting is used. Since the current of each phase of the U phase and the W phase flows directly in each of the CTs 20 and 21, two primary terminals on the power source side and the load side of the CT and the primary side connection conductors 11 that are respectively overlapped with these primary terminals. 13 is preferably firmly fixed using fasteners such as bolts and nuts.

  Each of the CT storage boxes 2, 3 also has two secondary side connection conductors 22 laid in advance for connecting a secondary output terminal block 17, which will be described later, and the secondary terminals of CTs 20, 21, 23; 24, 25 are drawn through through holes (not shown) provided in the partition walls of the respective storage boxes. As the secondary side connection conductor, a conductor that can be used as the primary side connection conductor can be used, but the insulated wire is preferably used. Known connecting means is provided at the tip of each of the two secondary side connection conductors 22 to 25 on the side drawn into each CT storage box so that it can be easily connected to each of the secondary terminals of the CTs 20 and 21. Is preferred. As such connection means, for example, various crimp terminals and male and female connection connectors, for example, combinations of various plugs and corresponding sockets can be suitably used. When a connection connector is used, it is preferable to connect and fix the female connector to the CT secondary terminal on the power supply side and the male connector to the tips of the secondary connection terminals 22 to 25.

  Branch conductors 11c, 12c, and 13c extending from the primary side connection conductors 11, 12, and 13 are drawn into the VT storage box 4, respectively. These branch conductors 11 c, 12 c, and 13 c are arranged so that their tips protrude into the VT storage box 4. The projecting length of each branch conductor is preferably set to such an extent that there is no problem when a later-described VT 30 is accommodated in the VT accommodating box 4.

  As the VT 30, a three-phase VT is used as shown in FIG. 1. This three-phase VT30 is formed by winding two primary windings and secondary windings around an annular iron core and V-connecting them, and a primary terminal to which each of the three-phase three-wires can be connected to the primary side. And a secondary terminal capable of transforming a voltage between U-V (reference phase), V (reference phase) -W phase, and outputting each transformed voltage signal on the secondary side. Although two single-phase VTs can be used instead of the three-phase VT, it is preferable to use a three-phase VT from the viewpoint of simplifying the internal structure.

  When the VT 30 is accommodated in the VT storage box 4, a connecting means is provided for each primary terminal of the VT 30 in order to securely connect the branch conductors 11c, 12c, 13c and the primary terminal of the VT 30. I can leave. In FIG. 1, flat connection pieces 31 to 33 are used as such connection means, and these are fixed to the primary terminal of the VT 30. The lengths of the connection pieces 31 to 33 are such that when the VT 30 in which the connection pieces 31 to 33 are connected to the primary terminals is stored in the VT storage box 4, the free ends of the connection pieces 31 to 33 are the VT storage boxes. It is preferable that the lower surfaces of the connection pieces 31, 32, 33 abut on the upper surfaces of the branch conductors 11 c, 12 c, 13 c without contacting the inner surfaces of the four partition walls. If necessary, these connecting pieces 31 to 33 can also be provided with long holes or the like penetrating front and back in the length direction.

  The interphase voltage of the AC circuit is applied to the primary side of the VT 30. However, since the impedance of the primary winding is large, the current flowing through the primary winding is relative to the current flowing through the CT. Is not big. For this reason, each connection piece and each of the primary connection conductors may simply be in contact with each other, but both are preferably firmly fixed using a fastener such as a bolt and a nut.

  Three secondary side connection conductors 35, 36, and 38 laid in advance for connecting the secondary terminal of the VT 30 and the secondary side output terminal 17 pass through a predetermined partition wall of the VT storage box 30 (not shown). It is drawn through the hole. As the secondary side connection conductors 35, 36, and 38, various insulated wires can be used as in the case of the CT. Connection means can be provided at the tip of each secondary connection conductor so that the connection to the secondary terminal of the VT 30 is easy. As this connection means, the same thing as the connection connector etc. which were fixed to the front-end | tip of the secondary side connection conductor connected to said CT can be mentioned. Connection to the secondary terminal of VT30 is preferably performed in the same manner as in the case of CT. The other ends of the secondary side connection conductors 35, 36, 38 connected to the VT 30 are connected to predetermined terminals of the secondary side terminal block 17 provided separately.

  As described above, the secondary side terminal block 17 includes a terminal row to which the secondary side connection conductors connected to the secondary terminals of the CTs 20 and 21 and the VT 30 are respectively connected, and an external conducting to each terminal of the terminal row. It consists of a series of output terminals.

  The external output terminal 17 is connected to an external signal line for sending a current signal and a voltage signal to, for example, a power meter. As such an external signal line, an instrument multicore cable 52 is preferably used. The multi-core cable for instrument 52 is drawn into the outer box 10 through a through hole provided in the side wall of the outer box 10 or the like. Thus, by arranging the secondary output terminals together in one place, it becomes possible to connect the multicore cable 52 for instruments, and as a result, it is difficult to cause misconnection or the like.

  When the voltage / current transformer of the present invention is used in, for example, a high-voltage AC circuit, the outer housing 10 is connected to the CT housing boxes 2 and 3 and the VT housing box 4, the secondary output terminal block 17 and the terminal block 17. Except for the space necessary for connection, molding may be performed using a resin such as a known epoxy resin to ensure insulation.

  FIG. 2 is a side cross-sectional view schematically showing another embodiment of the voltage / current transformer of the present invention. In the embodiment shown in this figure, the outer box 10 has a two-stage structure on the top and bottom, two CT storage boxes 2 are installed on the upper stage, and a VT storage box 4 is provided on the lower stage. Further, another CT storage box 3 having the same shape and size as the CT storage box 2 and capable of storing CT is provided on the back side of the CT storage box 2 as viewed in this figure. It shall be.

  The CT storage box 2 has a rectangular parallelepiped box shape, and the upper edge of the peripheral wall is in contact with and fixed to the peripheral edge of the openable / closable opening 2 a formed on the upper surface of the outer box 10. The peripheral edge of the opening 2a is bent outward, and the opening 2a can be opened and closed by the lid member 10a. By removing the lid member 10a, the CT 20 can be taken in and out from the upper surface, and can be easily maintained and inspected.

  The VT storage box 4 also has a rectangular parallelepiped box shape like the CT storage box 2, and its side surface (right side surface as viewed in the drawing) is an opening, and the upper and lower sides and the front and rear sides (both shown in the drawing). Is facing and fixed from the inner side to the peripheral wall of the opening formed on the side wall of the outer box 10. This opening is also covered with the lid member 10b, and by removing the lid member 10b, the VT 30 can be taken in and out, and maintenance can be easily performed.

  The VT 30 is mounted on a cart 40 with a roller. The lid 10b is opened, and this cart is directed from the opening (right toward the drawing) toward the back side (left toward the drawing) of the VT storage box 4. 40 is accommodated by sliding. In order to restrict the sliding movement of the carriage in one direction, a known guide means can be provided.

  A branch conductor 31 branched from the primary connection conductor 11 is drawn into the VT storage box 4 from above through a through hole (not shown) provided in the partition wall of the storage box 4. In order to easily connect the tip of the branch conductor 31 and the primary terminal of the VT 30, in FIG. 2, the substantially L-shaped connector 301 formed in a pin jack shape with the tip facing in the sliding movement direction is VT 1. A receiving plug 311 of the pin jack-like connector is fixed to the tip of the branch conductor 31.

  In the embodiment shown in FIG. 2, the configuration other than that described above is essentially the same as that of the embodiment shown in FIG. Also in this embodiment, the resin mold can be applied to the space excluding the storage boxes from the outer box 10.

  FIG. 3 is a connection diagram for performing power metering using the voltage / current transformer 1 of the present invention illustrated in FIGS. 1 and 2. In this figure, the code | symbol 10 has shown the outer case of the voltage current transformation apparatus 1 of this invention. The primary side terminals 11a, 12a, 13a on the power supply side exposed on the surface of the outer box 10 and the primary side terminals 11b, 12b, 13b on the load side are respectively phase phases from the power supply side and the load side. Conductors U, V, W and U1, V1, W1 are connected to each other. A secondary terminal block 17 is provided on the surface of the outer box 10, one end of a multi-core (7-core) cable for an instrument is connected to the secondary terminal block 17, and the wattmeter 50 is connected to the other end. Connected to the input terminal 51.

  In this way, by using the voltage / current transformer of the present invention, CT and VT are separately installed, and compared with the case where the amount of power in the AC circuit is measured, the wiring between CT and VT is unnecessary. Since the number of connections is small and a multicore cable for instruments can be used, it is possible to prevent erroneous connections.

  FIG. 4 is a plan sectional view schematically showing another embodiment of the voltage / current transformer of the present invention. In this figure, the embodiment shown in FIG. 1 differs from the embodiment shown in FIG. 1 in that the CT20, 21 and VT30 are connected to the secondary terminals at one end of the seven secondary connection conductors. Secondary connection conductors 22 and 24 connected to the secondary terminal on the power supply side and two secondary connection conductors 35 and 38 connected to the secondary terminals of VT 30 in phase with these CTs 20 and 21. By connecting each of them (the connection positions are not particularly limited), the number of terminals in the secondary output terminal block 17 is five, and the other is substantially the same as the embodiment shown in FIG. There is no change. Note that, in the embodiment shown in FIG. 4 as well, it is possible to mold using resin as in the above embodiments.

  FIG. 5 is a connection diagram for performing power metering using the voltage / current transformer of the present invention shown in FIG. In the metering system shown in this figure, the voltage-current transformer 1 of the present invention is used, and the phase conductors of the respective phases are connected to the power supply side and load side primary terminals of the transformer 1 and the secondary side. One end of an instrument multicore cable 52 is connected to the terminal block 17 (5 terminals), and the other end is connected to the input terminal 51 of the watt-hour meter 50.

  As shown in FIG. 5, by using the voltage / current transformer of the embodiment shown in FIG. 4, in the case of a three-phase three-wire AC circuit, the secondary output terminal can be set to five terminals. As a result, a secondary current of CT can be supplied together with a VT secondary voltage to a single watt hour meter (no need to use a transformer combination meter) via a multicore cable for an instrument connected to each of these terminals. As a result, the amount of electric power can be measured.

  The present inventor connects the voltage line excluding the reference phase on the VT secondary side to the power supply side of the CT secondary current line that is in phase with the voltage line, and applies the VT secondary voltage to the current line. In the case of a three-phase three-wire AC circuit, for example, in the case of a three-phase three-wire AC circuit, a voltage line is connected to the current line on the power source side in this way, so that a total of five current lines and voltage lines Has been found to be able to measure the amount of electric power by connecting to a single watt hour meter, and has already filed a patent application as an electric energy measuring method and an electric energy measuring device (Japanese Patent Application No. 2005-186007). The present embodiment is an application of this prior invention.

  By accommodating predetermined VT and CT in the voltage / current transformer of this embodiment, regardless of whether the AC circuit is at a low voltage or a high voltage, a single instrument can be used for a low voltage, If the electric 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, there is an advantage that the versatility of the single instrument can be improved. This shows that the cost reduction can be expected because it is possible for the instrument maker to reduce the number of manufactured products and facilitate inventory management.

  As is clear from the above description, by using the voltage / current transformer of the present invention, it becomes possible to simplify the connection when installing CT or VT in the AC circuit, and not only can prevent erroneous connection, The wiring work required for the installation of the equipment can be made more efficient and the working time can be shortened.

  In addition, the voltage / current transformer of the present invention can be used by simply replacing the current / current transformer with a CT having a current ratio corresponding to the size of the load even when the load on the AC circuit changes greatly. There is an advantage that there is no need to do. Even if the voltage of the AC circuit is greatly changed, the voltage / current transformer of the present invention can be used as it is by replacing only VT.

  The voltage / current transformer of the present invention can be installed in various electrical AC circuits by allowing the required number of CTs and VTs set appropriately based on a known power metering method to be accommodated in the outer box. Thus, it is possible to transform the voltage and current of the AC circuit with this single unit. Specifically, the electric system may be either single-phase or three-phase, the former being either a single-phase two-wire system or a single-phase three-wire system, and the latter being either a three-phase three-wire system or a three-phase four-wire system. It may be. Preferably, the voltage / current transformer of the present invention is installed in an AC circuit having a large number of phase wires of at least three wires.

  The voltage / current transformer according to the present invention is also used for measuring the electric energy of an AC circuit, by connecting a part of the secondary side connection conductor as described above, in spite of using CT or VT. Without using a transformer combined watt-hour meter, it becomes possible to measure the amount of power using a single watt-hour meter. In recent years, since the measuring accuracy of single meters has been remarkably improved in recent years, it can be expected to improve versatility when they are used for power transactions by passing a test based on the measurement method.

  Further, the voltage / current transformer of the present invention can accommodate a high piezoelectric path by accommodating VT and CT corresponding to the rated voltage and load current of the AC circuit and applying a predetermined insulation treatment.

  In addition, when measuring the electric energy of an AC circuit using the voltage / current transformer of the present invention, the watt-hour meter to be used may be either an electronic type or an induction type, and has various signal output functions such as a pulse transmission function. You may have.

  The voltage / current transformer of the present invention can be installed particularly in a low-voltage AC phase conductor path such as a general home or factory, and can be effectively used for measuring the electric energy of the electric line. Further, by providing a predetermined insulation in the voltage / current transformer of the present invention, it can be used for a high-voltage AC circuit.

It is a plane sectional view showing roughly one embodiment of the voltage current transformer of the present invention. It is a plane sectional view showing roughly another embodiment of the voltage current transformer of the present invention. FIG. 3 is a connection diagram for measuring the electric energy of a three-phase AC circuit using the voltage / current transformer shown in FIG. 1 or 2. It is a plane sectional view showing typically another embodiment of the voltage current transformer of the present invention. It is a connection diagram for measuring the electric energy of a three-phase alternating current circuit using the voltage-current transformer shown in FIG. It is a connection diagram in the case of measuring the electric energy of a low voltage | pressure three-phase alternating current circuit using VT and CT.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Voltage current transformer 2, 3 CT storage box 4 VT storage box 2a, 3a, 4a Opening 10 Outer box 10a, 10b Opening 11, 12, 13 Primary side connection conductor 11a, 12a, 13a Primary side terminal (power supply side )
11b, 12b, 13b Primary side terminal (load side)
11c, 12c, 13c Branch line 17 Secondary output terminal 20, 21 CT
22, 23, 24, 25 Secondary connection conductor 30 Three-phase VT
31, 32, 33 Connection pieces 35, 36, 38 Secondary side connection conductor 40 Roller-equipped cart 52 Multi-core cable for instrument U, V, W AC circuit (power supply side)
U1, V1, W1 AC circuit (load side)

Claims (7)

  A group of primary side connection conductors having a pair of primary side terminals capable of respectively connecting a power source side load element and a load side phase conductor of each phase of the AC circuit in an outer box provided with at least an opening that can be opened and closed; CT that can be connected in series to the primary side connection conductor that is in phase with each phase except the reference phase of the AC circuit, VT that can be connected in parallel to the primary side connection conductor, CT and VT And a group of secondary connection conductors that send outputs from these to the secondary output terminal, and the CT and the VT are detachably accommodated through the opening. A voltage-current transformer.   2. The voltage / current transformer according to claim 1, wherein the CT and / or the VT, or both of them are accommodated in an accommodation box provided inscribed in a peripheral area of the opening.   3. The primary connection conductor according to claim 1, wherein a tip end region of the primary connection conductor protrudes into each storage box and is connected to the primary terminal of the CT or the VT directly or through a connection unit. Voltage current transformer.   4. The secondary connection conductor according to claim 1, wherein a tip region of the secondary connection conductor protrudes into the housing box and is connected to the secondary terminal of the CT or the VT directly or via a connection means. The voltage-current transformer according to Item.   The secondary connection conductor connected to the power supply side of the secondary terminal of the CT and the secondary connection conductor of the VT that is in phase with the phase where the CT is installed are connected to each other. The voltage / current transformer according to any one of the above.   The voltage / current transformer according to claim 1, wherein the CT includes a primary terminal, and the VT is a three-phase VT. The voltage-current transformer of any one of Claims 1-6 installed in a low voltage | pressure alternating current circuit.

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