JP3982973B2 - Current transformer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molded current transformer in which a primary winding and a secondary winding are integrally formed of an insulating resin.
[0002]
[Prior art]
Conventionally, a current transformer that operates an ammeter or a relay connected to the secondary winding by forming a primary circuit by connecting the primary winding in series with the high-voltage side bus and converting the primary winding current to a low current. (Hereinafter referred to as CT) is an electrical device that is indispensable for power distribution equipment as an abnormal current detection sensor for current measurement and circuit protection. As shown in FIG. It is stored together with electrical equipment and insulation equipment. In the figure, 21 is a bus bar room, 22 is a load cable room, 23 is a circuit breaker room, 24 is a control room, 25 is a bus bar, 26 is a load cable, 27 is a drawer type circuit breaker, 29 is a through bushing, 10 is a CT is there.
[0003]
21, 31, 41 are doors, 51 is a busbar connection end, and 61 is a load cable connection end. Then, the applicant of the present invention proposed an instrument transformer as Japanese Patent Application No. 2000-046763 in order to reduce the distance between the high-voltage side buses of closed-type power distribution equipment such as switchboards as much as possible. is doing. This is a grounding type instrument in which the primary and secondary windings are arranged concentrically and are integrally covered with an insulating resin such as epoxy resin, and provided with a primary winding connection terminal portion connected to the high-voltage side bus bar at the top. Transformers for transformers and instrument transformers such as CT.
[0004]
[Problems to be solved by the invention]
By the way, as shown in the electrical connection diagrams of FIG. 5 and FIG. 6, the CT is normally connected to the R phase, S phase, T phase, and each phase in series with the high-voltage bus. The distance in the interphase direction increases, and the interphase distance of the high-voltage busbars is increased more than necessary. As a result, as the interphase distance of the high-voltage side buses increases, not only does the enclosure of the closed-type power distribution equipment such as switchboards increase in size, but the high-voltage side buses cannot be wired straight, and the outer two phases of the CT installation part In many cases, it is necessary to locally fold the high-voltage side bus to be connected to perform an expansion process of the interphase distance. In particular, the so-called wire-wound CT that connects to the high-voltage bus that flows a relatively small current (300 A or less) and takes in the bus current is required to increase the ampere turn by winding the primary winding multiple times. There was an inconvenience that the interphase distance of the high-voltage busbars was increased. In this way, CT has become one of the obstacles to reducing the installation area by reducing the size of closed power distribution facilities such as switchboards and reducing costs.
[0005]
Gas-insulated switchgears such as cubicle-type gas-insulated switchgear (hereinafter referred to as C-GIS) or closed-type gas-insulated switchgear (hereinafter referred to as GIS) are also used for miniaturization of the built-in equipment and the distance between the high-voltage side busbars. As a result, the dimensions of the CT in the inter-phase direction were an obstacle to the reduction in the inter-phase distance of the high-voltage side buses, and in turn, the miniaturization of the entire apparatus.
Accordingly, an object of the present invention is to provide a closed-type power distribution facility such as a power distribution panel or the like, which is required to be more compact and cost-effective, or a molded CT that is compatible with C-GIS and GIS.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of claim 1 is a winding composed of a cylindrical primary winding and a secondary winding arranged concentrically, and the outer radius and the secondary winding of the primary winding A flat cylindrical winding having a dimensional difference with the inner radius of the wire larger than its axial length, long in the radial direction, and short in the axial direction;
A shaft conductor whose lower end is connected to one end of the primary winding;
A cylindrical conductor having a lower end connected to the other end of the primary winding and disposed coaxially with the shaft conductor;
An insulating portion in which the entire surface of the flat cylindrical winding and a part of the cylindrical conductor are covered, filled between the shaft conductor and the cylindrical conductor, and a central hole penetrating the flat cylindrical winding is formed;
A primary winding connecting terminal portion formed by forming a cylindrical protrusion integrally with the insulating portion by insulating resin in the upper vertical direction of the main body, and arranging a shaft conductor and a cylindrical conductor at the center portion thereof
Two sets of halved iron cores, which are approximately U-shaped with the dimensional difference between the outer peripheral surface and the inner peripheral surface being smaller than the axial length, are clamped while being inserted into the central hole of the insulating part, and the outside is tightened with a band A substantially round-shaped cut core that is fixed and arranged so that the outer surface is perpendicular to the axial direction of the flat cylindrical winding;
As a whole, the width in the same direction as the axial direction of the flat cylindrical winding is reduced.
[0007]
According to a second aspect of the present invention, in the first aspect of the invention, the lower surface of the primary winding connection terminal portion is a large diameter portion, the upper portion is a small diameter portion, and a surface perpendicular to the axial direction formed in the stepped portion is defined as an attachment surface. It is characterized by that.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an external view of a CT according to the present invention, and FIG. 2 is a longitudinal sectional view showing main parts. As shown in the figure, the cylindrical primary winding 1 and secondary winding 2 are arranged concentrically and are integrally formed with an insulating resin 3 such as an epoxy resin.
A cylindrical protrusion 4 is formed from the upper end of the primary winding 1 by an insulating resin 3 in the vertical direction upward. A central conductor 5 and a cylindrical conductor 6 made of copper or copper alloy are coaxially arranged at the center of the projecting portion 4. The axial conductor 5 and the cylindrical conductor 6 form a reciprocal electric circuit, and a primary winding connection terminal. As a part.
[0009]
The lower ends of the shaft conductor 5 and the cylindrical conductor 6 are respectively connected to both ends of the primary winding 1. A large-diameter portion is formed at the lower portion of the projecting portion 4, and a small-diameter portion is formed at the upper portion, and a surface perpendicular to the axial direction formed at the step portion is used as the attachment surface 7. A groove 8 for mounting a seal member is formed near the outer periphery of the mounting surface 7, and a screw seat 9 is formed inside the groove 8.
The lower part of the primary winding 1 protrudes downward and leg portions 11 are formed on both sides. Between the recesses between the both leg portions 11 and the central holes of the primary winding 1 and the secondary winding 2, an iron core is used. A certain cut core 12 is sandwiched, and the outside thereof is fastened and fixed by a band 13.
[0010]
The secondary winding 2 is drawn out to the side surface via a lead wire (not shown) and connected to the secondary terminal 14 embedded in the surface of the insulating resin. Further, if necessary, a tertiary winding (not shown) that forms an open triangular connection to detect a zero-phase current can be provided inside or outside the secondary winding 2 and drawn to a tertiary terminal (not shown). It is configured.
Here, in general, the CT winding has a thick primary wire and a secondary winding, and since the number of turns is small, the radial difference between the cylindrical surface outer diameter and the cylindrical surface inner diameter is larger than the cylinder length. It is easy to form a cylindrical shape, that is, a flat cylindrical winding. By using this flat cylindrical winding, the dimension in the interphase direction is greatly reduced.
[0011]
In this embodiment, since the cut core 12 is fastened and assembled with the band 13, it is not necessary to fix and hold the cut core via the frame. Therefore, the assembly of the cut core is extremely easy and the structure is also simple. Become. Further, the CT main body can be directly mounted on a partition wall such as a switchboard via the mounting surface 7 of the protrusion 4.
The primary winding connection terminal portion projects the concentric shaft conductor 5 and the cylindrical conductor 6 from the insulating resin surface, and forms, for example, a reciprocating circuit having the shaft conductor 5 as the K terminal and the cylindrical conductor 6 as the L terminal. Can be connected to the side bus.
[0012]
Further, the shaft conductor 5 protrudes further from the cylindrical conductor 6, and the tip connection portion has a stepped structure, and the space between the shaft conductor 5 and the cylindrical conductor 6 is filled and fixed with an insulating resin 3, so that the shaft conductor 5 is The tulip connector is easy to connect the cylindrical conductor 6 to the high-voltage side bus via the pair of Ω-type connectors, and there is no contact.
The mounting surface 7 is provided with a screw seat 9 through which the CT main body passes the primary winding connection terminal portion through the partition wall surface and a groove 8 for inserting an airtight seal material, and an electric field relaxation shield is provided for the partition wall. Therefore, CT alone makes it easy to attach to GIS.
[0013]
CT equipped with the primary winding connection terminal part consisting of the above-mentioned reciprocating electric circuit and the mounting surface 7 can be mounted on C-GIS and GIS, while arranging the flat cylindrical surface of CT itself in the interphase direction, and the primary winding By increasing the outer peripheral surface close to the ground (iron yoke part, bulkhead, etc.) and interposing an epoxy resin with a high dielectric constant to ensure dielectric strength, it is almost possible to increase the vertical dimension even if the interphase dimension is reduced as much as possible. Has no effect. Thus, the three CT units according to the present embodiment are arranged in parallel as shown in FIG. 3 and connected to the high voltage side bus via the connector (not shown), thereby reducing the correlation distance of the high voltage side three phase bus. Closed-type power distribution equipment such as switchboards or C-GIS and GIS housing dimensions can be reduced.
[0014]
【The invention's effect】
As described above, according to the present invention, it is possible to reduce the inter-phase distance of the high-voltage side bus, especially by arranging the three-phase molded CT with reduced phase dimensions and connecting it to the high-voltage side bus. Therefore, it is possible to reduce the cost of closed-type power distribution equipment such as switchboards or C-GIS and GIS as a whole.
[Brief description of the drawings]
FIG. 1 is a diagram showing an external appearance of an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing a main part of the embodiment.
FIG. 3 is an external view showing an example of use of the embodiment.
FIG. 4 is a diagram showing an arrangement of a conventional switchboard.
FIG. 5 is a connection diagram showing an example of CT attachment.
FIG. 6 is a connection diagram showing an example of CT attachment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Primary winding 2 Secondary winding 3 Insulation resin 4 Protrusion part 5 Axial conductor 6 Cylindrical conductor 7 Mounting surface 8 Groove 9 Screw seat 11 Leg part 12 Cut core 13 Band

Claims (2)

A winding composed of a cylindrical primary winding and a secondary winding arranged concentrically, and the dimensional difference between the outer radius of the primary winding and the inner radius of the secondary winding is larger than its axial length. A flat cylindrical winding that is long in the radial direction and flat in the axial direction;
A shaft conductor whose lower end is connected to one end of the primary winding;
A cylindrical conductor having a lower end connected to the other end of the primary winding and disposed coaxially with the shaft conductor;
An insulating portion in which the entire surface of the flat cylindrical winding and a part of the cylindrical conductor are covered, filled between the shaft conductor and the cylindrical conductor, and a central hole penetrating the flat cylindrical winding is formed;
A primary winding connecting terminal portion formed by forming a cylindrical protrusion integrally with the insulating portion by insulating resin in the upper vertical direction of the main body, and arranging a shaft conductor and a cylindrical conductor at the center portion thereof
Two sets of halved iron cores, which are approximately U-shaped with the dimensional difference between the outer peripheral surface and the inner peripheral surface being smaller than the axial length, are clamped while being inserted into the central hole of the insulating part, and the outside is tightened with a band A substantially round-shaped cut core that is fixed and arranged so that the outer surface is perpendicular to the axial direction of the flat cylindrical winding;
The current transformer is characterized in that the width in the same direction as the axial direction of the flat cylindrical winding is reduced as a whole. The current transformer according to claim 1.
A current transformer characterized in that a lower portion of a primary winding connection terminal portion is a large diameter portion and an upper portion is a small diameter portion, and a surface perpendicular to the axial direction formed in the stepped portion is used as a mounting surface.

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