JP3541933B2 - Current transformer for instrument and its outer box - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a molded-type instrument current transformer that is installed at a service entrance of a low-voltage consumer for measuring an amount of electric power, and an outer box that houses the current transformer.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a current transformer for an instrument (hereinafter referred to as CT) is provided with a secondary terminal for connection with a service line of a watt hour meter attached to a secondary side thereof. 17 to 19 show a conventional CT and secondary terminal, FIG. 17 is a front view, FIG. 18 is a plan view, and FIG. 19 is a right side view. In these figures, 1 is a stand, 2 is a CT, 3 is a secondary terminal, and 4 is a terminal fitting. The secondary terminal 3 has a structure in which a terminal fitting 4 is integrally formed in an insulating resin. FIG. 20 is a connection diagram showing the connection between the CT 2 and the secondary terminal 3.
[0003]
When the CT 2 and the secondary terminal 3 are installed at the site, they are stored in an outer box. 21 to 23 show a conventional outer box, FIG. 21 is a front view, FIG. 22 is a plan view, and FIG. 23 is a view showing the inside. As shown in the figure, the outer box includes a main body 5 and a lid 6, and a lead-in hole is formed through the side surface of the main body 5, and a lead-in wire 7 is connected to a conductor 8 of the internal CT 2 through the lead-in hole. Is connected to
[0004]
[Problems to be solved by the invention]
However, regarding the CT 2, since the terminal fitting 4 is integrally formed on the secondary terminal 3, the resin used as the material of the secondary terminal 3 is required to have crack resistance. In order to satisfy these requirements, expensive resins such as phenol resin, urea resin, and melamine resin must be used, which has been a factor of cost increase. When the CT 2 and the secondary terminal 3 are housed in an outer box, the CT 2 and the secondary terminal 3 are formed to penetrate the side surface of the main body 5 of the outer box in order to connect the primary / secondary conductor 8 of the CT 2 and the drop wire 7. It was necessary to draw the drop wire 7 into the inside through the drop hole, which was inconvenient. In particular, when the power supply side is in a state where power is applied, the connection location of the CT 2 is restricted in terms of space, and the primary drop wire is thick and the wire coating is hard, the workability including the danger of short-circuiting, There was a problem with safety.
[0005]
[Means for Solving the Problems]
Therefore, in order to solve the above problem, the current transformer for an instrument according to the first aspect of the present invention has the primary conductor and the secondary conductor for three phases arranged in parallel with each other and integrally covers the CT for two phases with an insulating resin. Mold type CT,
A terminal arrangement portion formed by arranging projections at regular intervals by depressing the middle of the upper surface of the mold type CT ;
A secondary terminal cover made of insulating resin in which a plurality of vertically arranged partition walls and holes for screw insertion are alternately formed ,
And has a core wire insertion hole of the external lead wire, and a plurality of square pole fitting which is supported by the terminal screw from two of disposed between the barrier ribs and the upper surface is formed on the bottom surface of the secondary terminal cover holes ,
A plurality of secondary wire that connects the front Symbol fitting and current transformer body terminal portions,
Comprising a, when mounting the secondary terminal cover to the terminal arrangement portion, the partition wall is fitted in the groove portion between the two projections, the fitting adjacent to the lower surface of the secondary terminal cover with bulkhead shields, using The present invention is characterized in that all the connection fittings are supported while holding the connection fittings to which the secondary wiring is connected on the four sides of the connection fittings by the lower surface, the partition walls and the projections .
[0006]
The outer case for accommodating the current transformer for an instrument according to the second aspect of the present invention is a molded CT in which CT is covered with an insulating resin, and three phases of primary conductors and secondary conductors are arranged at the same height and are arranged side by side. An outer box for storing a current transformer for an instrument for storing the current transformer for an instrument,
A lower box in which a flange is formed on the upper edge, and a lead-in opening of a two-part structure is formed such that the primary conductor and the secondary conductor fit in this flange,
An upper box in which a flange is formed on the lower edge portion, and an inlet of a two-part structure is formed such that the primary conductor and the secondary conductor fit into the flange,
With
The primary and secondary conductors for the three phases of the current transformer for the instrument are arranged at the same height as the inlets of the lower and upper boxes, and the lower halves of the primary and secondary conductors are drawn into the lower box. By placing the upper box on the lower box in the state of being fitted in the mouth part, the primary conductor and the secondary conductor are in close contact with the inlets of the lower box and the upper box while the two flanges are in contact with each other. I do.
[0007]
According to a third aspect of the present invention , there is provided an outer box for accommodating a current transformer for an instrument according to the second aspect, wherein the current transformer for an instrument according to the first aspect is accommodated. characterized in that that.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 show an embodiment of a current transformer for an instrument according to the present invention. FIG. 1 is a front view, FIG. 2 is a plan view, and FIG. 3 is a right side view. In the figure, reference numeral 11 denotes a molded CT, which covers two phases, that is, U-phase and W-phase CTs with an insulating resin such as an epoxy resin, and moves conductors 12 for three phases of U-phase to W-phase. it is obtained by integrating by Rukoto protrude in parallel and the same height. The conductor 12 is a primary conductor for the U-phase to W-phase power-supply-side three phases and a secondary conductor for the load-side three phases with respect to the molded CT11 depending on whether or not the voltage lead-in wiring for the terminals P1, P2 and P3 is connected. They are distinguished from conductors for convenience.
A U-shaped recess is formed in the upper middle portion of the molded CT 11 to form a terminal arrangement portion, and a secondary terminal cover 13 is fixed by two mounting bolts 14 so as to cover the terminal arrangement portion.
[0009]
Between the lower side of the cover 13 and the CT 11, the same number of connection fittings 15 as the secondary wirings 26 are supported. A secondary wiring 26 (not shown) is connected to the connection fitting 15 by a terminal screw 16. 4 and 5 show the appearance of the molded CT11 alone. FIG. 4 is a front view and FIG. 5 is a plan view thereof. Protrusions 17 are juxtaposed at regular intervals in a U-shaped depression above the CT 11. The upper surface of the projection 17 is a position where the connection fitting 15 is held during assembly. The pair of screw holes 18 on the upper surface is for attaching the cover 13.
[0010]
6 to 8 show the external appearance of the secondary terminal cover 13 alone, FIG. 6 is a front view, FIG. 7 is a plan view thereof, and FIG. 8 is a sectional view taken along line AA. In the figure, reference numeral 19 denotes a pair of mounting holes formed at both ends, the same number of box-shaped recesses 20 as secondary wirings are formed at regular intervals on the lower surface in the middle, and two through holes 21 are formed at the bottom thereof. Is formed. Further, partition walls 22 are provided vertically below the boundary between the concave portions 20 at equal intervals. The partition wall 22 is fitted into the groove between the protrusions 17 on the upper part of the CT 11 at the time of assembly.
[0011]
FIG. 9 shows the external appearance of the connection fitting 15 alone. The connection metal fitting 15 penetrates the hole 23 for inserting the core wire through the center axis portion of the rectangular pillar-shaped conductor block, forms two female screws 24 from the side surface to the hole 23, and further attaches the crimp terminal 25 to the side surface. It is fixed by brazing. Secondary wires 26 (not shown) are connected to the crimp terminals 25.
[0012]
10 to 12 show an assembly view of the secondary terminal cover. FIG. 10 is a front view, FIG. 11 is a plan view thereof, and FIG. 12 is a sectional view taken along line BB. In the figure, when assembling the secondary terminal cover 13, the connection fitting 15 in which the secondary wiring 26 has been fixed to the crimp terminal 25 in advance is inserted into the recess 20 from below the cover 13 with the female screw 24 facing upward. Press. Next, the terminal screw 16 is screwed into the female screw 24 from the inside of the recess 20 through the through hole 21. Thereafter, at an installation site or the like, the core wire is fixed by further screwing the terminal screw 16 in a state where the core wire (not shown) is inserted into the hole 23 of the connection fitting 15. In the state where the cover 13 is attached to the CT 11, the connection fitting 15 is held on its four sides by the cover 13 and the CT 11, and is fixed by terminal screws 16 in the longitudinal direction.
[0013]
FIG. 13 is a connection diagram showing a routing route of the secondary wiring 26 between the CT 11 and the connection fitting 15 of the cover 13. As shown in the figure, the terminal portions formed on each surface of the CT 11 and the corresponding connection fittings 15 are connected by the secondary wires 26 respectively. This connection diagram corresponds to the connection diagram of FIG.
In this embodiment, since the secondary terminal cover 13 has a single structure and the connection fitting and the like are no longer insert-molded, there is no limit to the type of resin used, and inexpensive resin is used. It becomes possible.
[0014]
Next, an embodiment of the invention of a storage outer box will be described.
14 to 16 show the storage outer box, FIG. 14 is a front view, FIG. 15 is a plan view, and FIG. 16 is a view showing the inside. In the drawing, 31 is a lower box forming the lower half of the storage outer box, and 32 is an upper box forming the upper half similarly. Flanges 34 and 35 are formed on the upper edge of the lower box 31 and the lower edge of the upper box 32, respectively. The flanges 34 and 35 are in contact with each other. An outer box for storing the CT 11 is formed. The level at which the flanges 34 and 35 come into contact with each other matches the level of the conductor 8 of the CT 11 housed therein, and the inlets 36 are formed at the flanges 34 and 35 on the extension of the conductor 8 respectively. The CT 11 to be housed includes a plurality of conductors 8, all of which are arranged at the same level.
[0015]
Naturally, the inlet 36 also has a two-part structure, and is opened with the upper box 32 lifted. In this state, the conductor 8 and the drop wire 37 are connected via the connection fitting 38, and the lower half of the drop wire 37 is fitted into the drop port 36 of the lower box 31, and the connection of the drop wire 37 is completed. I do. Next, the upper box 32 is put on the lower box 31 so that the flanges 34 and 35 of the upper box 32 abut each other, and the upper half of the drop wire 37 is also covered by the drop port 36. In this state, the upper box 32 is integrated with the lower box 31 by tightening and fixing the four corners of the flanges 34 and 35 from above and below with bolts 39 and nuts 40, and the drop wire 37 is brought into close contact with the drop port 36. .
[0016]
With this configuration of the storage outer box, the troublesome work of inserting the drop wire through the drop hole, which has been conventionally required, is released, and workability is remarkably improved. This is particularly effective when working in a live state.
Note that, in the above-described embodiment, the case where the CT 11 is housed has been described, but the present invention is also applicable to the case where the conventional CT 2 shown in FIG. 21 is housed.
[0017]
【The invention's effect】
As described above, according to the first aspect of the present invention, the connection fitting is not formed integrally with the terminal but is formed as a single body, so that the terminal cover supporting the connection fitting does not require crack resistance. As a result, expensive insulating resin is not required, and the cost can be reduced accordingly.
[0018]
According to the second and third aspects of the present invention, since the storage outer box has a two-part structure at a level where the drop line can be inserted, it is unnecessary to bend a hard and thick drop line and pass it through the pipe-shaped through hole. Therefore, the danger of a short circuit is reduced, and accordingly, workability and safety are improved even in a site where the work space is narrow.
[Brief description of the drawings]
FIG. 1 is a front view showing an embodiment of an instrument current transformer according to the present invention.
FIG. 2 is a plan view of FIG.
FIG. 3 is a right side view of FIG. 1;
FIG. 4 is a front view showing the appearance of the mold type CT unit of FIG. 1;
FIG. 5 is a plan view of FIG. 4;
FIG. 6 is a front view showing a single unit of the secondary terminal cover of FIG. 1;
FIG. 7 is a plan view of FIG. 6;
FIG. 8 is a sectional view taken along line AA of FIG. 7;
9 is an external view of a single piece of the connection fitting of FIG. 1;
FIG. 10 is a front view showing an assembled state of the secondary terminal cover of FIG. 1;
FIG. 11 is a plan view of FIG. 10;
FIG. 12 is a sectional view taken along line BB of FIG. 11;
FIG. 13 is a connection diagram showing secondary wiring between a CT and a secondary terminal cover.
FIG. 14 is a front view showing an embodiment of a storage outer box according to the present invention.
FIG. 15 is a plan view of FIG.
FIG. 16 is a view showing a state where an upper box is removed from FIG. 15;
FIG. 17 is a front view showing a conventional current transformer for an instrument.
18 is a plan view of FIG.
FIG. 19 is a side view of FIG. 17;
20 is a connection diagram showing the connection between the CT and the secondary terminal in FIG. 17;
FIG. 21 is a front view of an outer box in which a conventional current transformer for an instrument is stored.
FIG. 22 is a plan view of FIG. 21.
FIG. 23 is a diagram showing the inside of FIG. 22;
[Explanation of symbols]
11 Molded CT
DESCRIPTION OF SYMBOLS 12 Conductor 13 Secondary terminal cover 14 Mounting bolt 15 Connecting bracket 16 Terminal screw 17 Projection 18 Screw hole 19 Mounting hole 20 Depression 21 Through hole 22 Partition wall 23 Hole 24 Female screw 25 Crimp terminal 26 Secondary wiring 31 Lower box 32 Upper box 34, 35 Flange 36 Drop-in port 37 Drop-in wire 38 Connection fitting 39 Bolt 40 Nut

Claims (3)

A molded CT in which primary and secondary conductors for three phases are arranged side by side and CT for two phases is integrally coated with an insulating resin ;
A terminal arrangement portion formed by arranging projections at regular intervals by depressing the middle of the upper surface of the mold type CT ;
A secondary terminal cover made of insulating resin in which a plurality of vertically arranged partition walls and holes for screw insertion are alternately formed ,
A plurality of quadrangular prism-shaped connection fittings having a core wire insertion hole for the external lead wire, disposed on the lower surface of the hole of the secondary terminal cover, disposed between the two partitions, and supported by terminal screws from the upper surface,
A plurality of secondary wirings for connecting the connection fittings and the respective terminals of the current transformer main body,
When attaching the secondary terminal cover to the terminal arrangement portion, the partition is fitted into the groove between the two protrusions, and the partition shields and uses the connection fitting adjacent to the lower surface of the secondary terminal cover. A current transformer for an instrument , wherein all of the connection fittings are supported while holding the connection fitting to which the secondary wiring is connected on the four sides of the connection fitting by the lower surface, the partition wall, and the projection . It is a molded CT in which a CT is covered with an insulating resin, and a primary current transformer and a secondary conductor for three phases are arranged at the same height position, and a current transformer for an instrument which houses an instrument current transformer is provided. A storage outer box,
A lower box in which a flange is formed at the upper edge, and a lead-in opening of a two-part structure is formed such that the primary conductor and the secondary conductor fit into this flange,
An upper box in which a flange is formed on the lower edge portion, and an inlet of a two-part structure is formed such that the primary conductor and the secondary conductor fit into this flange,
With
The primary and secondary conductors for the three phases of the current transformer for the instrument are arranged at the same height as the inlets of the lower and upper boxes, and the lower halves of the primary and secondary conductors are drawn into the lower box. By placing the upper box on the lower box in the state of being fitted in the mouth part, the primary conductor and the secondary conductor are in close contact with the inlets of the lower box and the upper box while the two flanges are in contact with each other. Outer box for instrument current transformers. The storage outer box of the current transformer for an instrument according to claim 2,
An outer case for accommodating a current transformer for an instrument, wherein the current transformer for an instrument according to claim 1 is accommodated .

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