JP2000353631A - Current transformer for instrument and its outer box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable inexpensive manufacture of a secondary terminal part of a CT(current transformer for instrument) and easy and safe connecting work of a lead wire for the conductor of the CT. SOLUTION: A middle part of the upper surface of a main body of a CT 11 is depressed to form a terminal disposition part, a terminal cover 13 made of insulating resin, having a plurality of holes for passage of screws formed therein, is mounted on the terminal disposing part, a plurality of connecting metal fittings 15 having holes for insertion of cores of external lead wires are provided at the lower faces of the holes of the terminal cover 13 and then supported from their upper side by means of terminal screws. Next the connecting fittings 15 and the terminal parts of the main body of the CT 11 are connected by a plurality of secondary wiring lines. Furthermore, an outer storage casing is of a divided structure which have upper and lower split box sections.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded-type instrument current transformer which is installed at a service entrance of a low-voltage consumer for measuring electric energy, and an outer box for housing the same.

[0002]

2. Description of the Related Art Conventionally, a current transformer for an instrument (hereinafter referred to as a CT).
Is provided with a secondary terminal for connection with a service line of a watt hour meter attached to the secondary side. Fig. 17
FIG. 19 shows a conventional CT and secondary terminal, and FIG.
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 on site, they are housed in an outer box. 21 to 23 show a conventional outer box, FIG. 21 is a front view, FIG. 22 is a plan view, FIG.
It is a figure which shows 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]

However, regarding the CT 2, since the terminal fittings 4 are 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 is one of the causes of cost increase. When the CT 2 and the secondary terminal 3 are housed in an outer box, the primary and secondary conductors 8 and the drop-in wires 7 of the CT 2 are used.
In order to connect the cable, the lead wire 7 needs to be drawn into the inside through a lead hole formed through the side surface of the main body 5 of the outer box, resulting in poor workability. In particular, when the power supply side is in a state where power is applied, the connection location of CT2 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]

In order to solve the above-mentioned problems, the invention of claim 1 arranges three-phase primary conductors and secondary conductors in parallel with each other, and two-phase CT is made of insulating resin. A current transformer for an instrument integrally coated, wherein a terminal arrangement portion formed by depressing the middle of the current transformer main body upper surface portion and a plurality of holes for screw insertion are formed and attached to the terminal arrangement portion. A plurality of connection fittings having an insulating resin terminal cover, a plurality of connection fittings having a core insertion hole for an external lead wire, and arranged on the lower surface of the terminal cover hole and supported by terminal screws from the upper surface; A plurality of secondary wirings for connecting each terminal portion of the flow device main body are provided.

A second aspect of the present invention is characterized in that, in the first aspect of the present invention, a plurality of partition walls are suspended from a lower surface of the terminal cover so as to shield adjacent connection fittings.

According to a third aspect of the present invention, there is provided an outer case for an instrument current transformer for accommodating an instrument current transformer in which a primary conductor and a secondary conductor are disposed at the same height position, Are formed into upper and lower two-part structures, and flanges are formed above and below the dividing position to contact each other, and a lead-in opening for inserting a lead-in wire connected to a conductor is formed in the flange part.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below 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, the U-phase and W-phase CTs with an insulating resin such as an epoxy resin, and has a U-phase to a W-phase three-phase conductor 12 in front and behind. They are formed in parallel and at the same height so as to protrude and are integrally formed. Also, a U-shaped recess is formed in the middle part of the upper part of the molded CT 11 to form a terminal arrangement part, and the secondary terminal cover 13 is
It is fixed by book mounting bolts 14.

[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. Connection bracket 15
Is connected to a secondary wiring 26 (not shown) 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. U on top of CT11
Protrusions 17 are juxtaposed at regular intervals in the letter-shaped depression.
The upper surface of the projection 17 is a position where the connection fitting 15 is held during assembly. In addition, a pair of screw holes 18 on the top
It is for attaching 13.

FIGS. 6 to 8 show the appearance of the secondary terminal cover 13 alone, FIG. 6 is a front view, FIG.
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 end portions. Box-shaped concave portions 20 are formed at regular intervals on the lower surface in the same number as the number of secondary wirings, and two through holes 21 are formed at the bottom thereof. Are formed. In addition, the concave
Below the boundary between the concave portion 20 and the concave portion 20, partition walls 22 are vertically provided at equal intervals. This partition wall 22 is fitted into a groove between the projections 17 on the upper part of the CT 11 during assembly.

FIG. 9 shows the external appearance of the connection fitting 15 alone.
The connection metal fittings 15 are formed such that a hole 23 for inserting a core wire is passed through a central axis portion of a
23, two female screws 24 are formed, and a crimp terminal 25 is fixed to the side surface by brazing. Secondary wires 26 (not shown) are connected to the crimp terminals 25.

FIGS. 10 to 12 show an assembly view of the secondary terminal cover. FIG. 10 is a front view, and FIG.
12 is a sectional view taken along the line BB. In the figure, when assembling the secondary terminal cover 13, the connection fitting 15, in which the secondary wiring 26 is 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 up. 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 assembled 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.

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 fittings and the like are no longer insert-molded, the type of resin used is not limited, and inexpensive resin is used. It becomes possible.

Next, an embodiment of the invention of a storage outer box will be described. 14 to 16 show a 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 figure, 31 is a lower box forming the lower half of the storage outer box, and 32 is an upper box also forming the upper half. At the upper edge of the lower box 31 and the lower edge of the upper box 32, flanges 34 and 35 are formed, respectively, and in a state where the flanges 34 and 35 are in contact with each other, the lower box 31 and the upper box 32 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. The CT 11 to be stored includes a plurality of conductors 8, all of which are arranged at the same level.

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 on the lower box 31 side. I do. Then
By placing the upper box 32 over the lower box 31, the flanges 34, 35
Are in contact with each other, and the upper half of the drop line 37 is also covered by the drop port 36. In this state, the four corners of the flanges 34 and 35 are tightened and fixed with bolts 39 and nuts 40 from above and below, so that the upper box
The lower box 32 is integrated with the lower box 31, and the lead 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 lead-in wire through the drop-in port, which has been conventionally required, is released, and workability is remarkably improved. This is particularly effective when working in a live state. In the above-described embodiment, the case where the CT 11 is stored has been described. Similarly, the conventional CT 2 shown in FIG.
It is also applicable to the case of storing.

[0017]

As described above, according to the first and second aspects of the present invention, the connection fitting is not formed integrally with the terminal but is formed as a single piece, so that the terminal cover supporting the connection fitting is required to have crack resistance. Will not be. As a result, expensive insulating resin is not required, and the cost can be reduced accordingly.

According to the third aspect of the present invention, the storage outer box has a two-part structure at a level at which the drop line is inserted,
It is not necessary to bend hard and thick lead-in wires and pass them through pipe-shaped through holes, reducing the risk of short-circuits.
Workability and safety are improved even in the workplace where the work space is narrow.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a current transformer for an instrument 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 molded CT alone 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;

FIG. 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 illustrating 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. 14;

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.

19 is a side view of FIG.

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 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 bracket 39 Bolt 40 Nut

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[Procedure amendment]

[Submission date] July 7, 2000 (200.7.7)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below 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, 11 is a mold type C
T, which covers two phases, that is, the U-phase and W-phase CTs, with an insulating resin such as an epoxy resin.
And parallel conductors 12 of three phases of phase before and after is obtained by integrating by Rukoto protrude in the same height. In addition,
The body 12 is connected to the terminals P1, P2, and P3 of
Depending on the presence or absence of connection, U phase-
Primary conductor for three phases on W-phase power supply side, secondary conductor for three phases on load side
Are distinguished for convenience. Also, 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 1 is formed so as to cover the terminal arrangement portion.
3 is fixed by two mounting bolts 14.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E043 EA04 EA05 EA06 EB01 EB02 EB04 EB05 5E081 AA05 AA11 BB03 CC30 DD03 DD13 DD14 FF07

Claims (3)

[Claims] 1. A current transformer for an instrument in which primary and secondary conductors for three phases are juxtaposed with each other and CTs for two phases are integrally coated with an insulating resin. And a terminal cover made of insulating resin attached to the terminal placement portion by forming a plurality of holes for screw insertion, and a core wire insertion hole for an external lead wire. A plurality of connection fittings arranged on the lower surface of the hole of the terminal cover and supported by terminal screws from the upper surface, and a plurality of secondary wirings connecting the connection fitting and each terminal portion of the current transformer main body. A current transformer for an instrument, characterized in that: 2. The current transformer for an instrument according to claim 1, wherein
A current transformer for an instrument, wherein a plurality of partition walls are suspended from a lower surface of a terminal cover so as to shield adjacent connection fittings. 3. A housing for an instrument current transformer for accommodating an instrument current transformer in which a primary conductor and a secondary conductor are disposed at the same height position, wherein the housing outer box is divided into upper and lower parts. Wherein, at the top and bottom of the dividing position, flanges that respectively contact each other are formed, and a lead-in port through which a lead-in wire connected to a conductor is inserted is formed in the flange portion. .