JP2001250731A - Current transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of an enclosed receiving and distributing facility, such as the switchboard, etc., by shortening interphase distances. SOLUTION: In a current transformer in which cylindrical primary and secondary windings 1 and 2 arranged on concentric circles are integrally molded by using an insulating resin 3 and, at the same time, a core is clamped to the outer peripheral sections and center hole of the windings 1 and 2, the windings 1 and 2 are formed in flat shapes by making the thicknesses of the windings 1 and 2 larger than their lengths and, at the same time, a cylindrical projecting section 4 which is vertically protruding upward from the main body is formed of the resin 3. In addition, a shaft conductor 5 and a cylindrical conductor 6 are coaxially arranged in the central part of the projecting section 4, and primary winding connecting terminal sections are formed by respectively connecting the lower ends of the conductors 5 and 6 to both ends of the primary winding 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field 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]

2. Description of the Related Art Conventionally, a primary circuit is formed by connecting a primary winding in series with a high-voltage side bus to transform a primary winding current into a low current, and an ammeter or a relay connected to a secondary winding is formed. The operating current transformer (hereinafter referred to as CT) is an indispensable electrical device for power distribution equipment as an abnormal current detection sensor for current measurement and circuit protection. As shown in Fig. 4, it is used for closed type power distribution equipment such as a switchboard. Inside, it is housed together with other electrical equipment and insulation equipment. In the figure, 21 is a bus room, 22 is a load cable room, 23 is a breaker room, 24 is a control room, 25 is a bus, 26
Is a load cable, 27 is a draw-out circuit breaker, 29 is a through bushing, and 10 is a CT.

[0003] Reference numerals 21, 31, and 41 denote doors, 51 denotes a bus connection end, and 61 denotes a load cable connection end. Then, in an attempt to reduce the inter-phase distance of the high-voltage side bus of a closed-type power receiving and distribution facility such as a power distribution panel as much as possible, the applicant of the present invention,
A transformer for an instrument is proposed as Japanese Patent Application No. 2000-046763.
This is a ground-type instrument in which the primary and secondary windings are arranged concentrically, are integrally coated with an insulating resin such as epoxy resin, and have a primary winding connection terminal connected to the high-voltage side bus at the top. Transformers and transformers for instruments such as CT.

[0004]

By the way, usually, CT
Is, as shown in the electrical connection diagrams of FIGS.
Since the phase, S phase, T phase, and each phase are connected in series with the high voltage side bus, the distance of each phase in the direction of CT itself increases, and the interphase distance of the high voltage side bus is unnecessarily expanded. as a result,
As the distance between the phases of the high-voltage bus increases, the size of the enclosure of the closed-type power receiving and distribution equipment such as the switchboard increases, and the high-voltage bus cannot be wired straight and is connected to the two outer phases of the CT installation part. In many cases, it is necessary to locally bend the high-voltage-side bus to perform a process of expanding the phase distance or the like. In particular, the so-called wound type CT, which connects to the high-voltage side bus through which a relatively small current (300 A or less) flows and takes in the bus current, is required to increase the ampere-turn by winding the primary winding a plurality of times. There is a disadvantage that the inter-phase distance of the high-voltage side bus increases. As described above, the CT has been one of the obstacles in minimizing the size of the closed power receiving and distributing equipment such as the switchboard to reduce the installation area and reduce the cost.

[0005] Gas-insulated switchgear such as cubicle-type gas-insulated switchgear (hereinafter referred to as C-GIS) or closed-type gas-insulated switchgear (hereinafter referred to as GIS) is also required to have smaller internal devices and high-voltage buses. Attempts have been made to reduce the inter-phase distance as much as possible to reduce the size of the entire apparatus, and the inter-directional dimension of the CT itself has been an obstacle to the reduction of the inter-phase distance of the high-voltage side bus, and consequently the miniaturization of the entire apparatus. Therefore, the present invention
It is an object of the present invention to provide a closed type power receiving / distributing facility such as a switchboard or the like, which is required to be more compact and lower in cost, or a mold type CT capable of supporting C-GIS and GIS.

[0006]

In order to solve the above-mentioned problems, a first aspect of the present invention is to form a cylindrical primary winding and a secondary winding arranged on concentric circles integrally with an insulating resin, In a current transformer having an iron core sandwiched between an outer peripheral portion and a center hole of the winding, a dimensional difference between an outer radius and an inner radius of the primary winding and the secondary winding is made larger than its axial length, and the flat cylindrical winding is formed. In addition to forming a wire, a cylindrical protrusion is formed by insulating resin in the upper part of the main body vertically, and an axial conductor and a cylindrical conductor are arranged coaxially at the center thereof, and the lower ends thereof are respectively connected to both ends of the primary winding. To form a primary winding connection terminal portion.

According to a second aspect of the present invention, in the first aspect, the lower portion of the primary winding connection terminal portion has a large diameter portion and the upper portion has a small diameter portion. It is characterized in that it is a mounting surface.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an external view of a CT according to the present invention,
FIG. 2 is a longitudinal sectional view showing a main part. As shown in the figure, a cylindrical primary winding 1 and a secondary winding 2 are arranged concentrically, and are integrally formed of an insulating resin 3 such as an epoxy resin. A cylindrical protrusion 4 is formed by the insulating resin 3 in a vertical direction from the upper end of the primary winding 1. An axial conductor 5 made of copper or a copper alloy is provided at the center of the protrusion 4.
And the cylindrical conductor 6 are arranged coaxially. A reciprocating electric path is formed by the shaft conductor 5 and the cylindrical conductor 6 to serve as a primary winding connection terminal portion.

The lower ends of the shaft conductor 5 and the cylindrical conductor 6 are connected to both ends of the primary winding 1 respectively. A large-diameter portion is formed at the lower portion of the protruding 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 mounting 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 portion of the primary winding 1 projects downward to form leg portions 11 on both sides, and an iron core is provided between the concave portion between the two leg portions 11 and the center holes of the primary winding 1 and the secondary winding 2. A certain cut core 12 is sandwiched, and the outside thereof is fixed by a band 13.

The secondary winding 2 is drawn out to the side via a lead wire (not shown) and is connected to a secondary terminal 14 embedded in the insulating resin surface. If necessary, a tertiary winding (not shown) for forming an open triangular connection and detecting a zero-phase current can be provided inside or outside the secondary winding 2 and can be drawn to a tertiary terminal (not shown). It has a configuration. Here, in general, the CT winding is such that the primary winding and the secondary winding are wound with a thick electric wire, and the number of windings is small, so that the radius difference between the outer diameter of the cylindrical surface and the inner diameter of the cylindrical surface is larger than the cylindrical length. It is easy to form a cylindrical shape, that is, a flat cylindrical winding, and this flat cylindrical winding greatly reduces the dimension in the interphase direction.

In this embodiment, since the cut core 12 is fastened by the band 13 and assembled, there is no need to fix and hold the cut core via a frame, so that the cut core is extremely easily assembled. Is also easier.
Further, the CT main body can be directly mounted on a partition wall such as a switchboard via the mounting surface 7 of the projection 4. The primary winding connection terminal portion protrudes the concentrically arranged shaft conductor 5 and cylindrical conductor 6 from the insulating resin surface, for example, forms a reciprocating electric path having the shaft conductor 5 as a K terminal and the cylindrical conductor 6 as an L terminal, thereby forming a high-voltage circuit. Can be connected to the side bus.

Further, the shaft conductor 5 protrudes further than the cylindrical conductor 6 so that the tip connecting portion has a stepped structure.
And the cylindrical conductor 6 are filled and fixed with the insulating resin 3, so that the shaft conductor 5 is easily connected to the tulip connector, and the cylindrical conductor 6 is easily connected to the high-voltage side bus via a pair of Ω-type connectors, and the contact is caused. Nothing. On the mounting surface 7,
The CT body is provided with a screw seat 9 for mounting the primary winding connection terminal portion through the partition wall surface and a groove 8 for inserting an airtight sealing material, and an electric field mitigation shield with the partition wall is provided.
It is easy to attach to GIS etc.

The CT having the primary winding connection terminal portion including the reciprocating electric path and the mounting surface 7 can be mounted on a C-GIS or a GIS, while arranging the flat cylindrical surface of the CT itself in the interphase direction. Even if the inter-direction dimension is reduced as much as possible by placing the outer peripheral surface of the primary winding close to the ground (iron yoke, partition wall, etc.) and securing the dielectric strength by interposing an epoxy resin with a large dielectric constant, the dimension in the vertical direction can be reduced. Has little effect on expansion. In this manner, 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 a connector (not shown), thereby reducing the correlation distance of the high-voltage side three-phase bus. In addition, it is possible to reduce the size of a closed power receiving and distributing facility such as a switchboard or a casing of a C-GIS or GIS.

[0014]

As described above, according to the present invention, it is possible to reduce the distance between the phases of the high-voltage side bus in particular by arranging the three-phase molded CT having reduced inter-phase dimensions and connecting to the high-voltage side bus. In addition, it is possible to reduce the size of a closed-type power receiving / distributing facility such as a switchboard or the like, which is required to be more and more compact, or to reduce the entire device such as a C-GIS or GIS, thereby contributing to cost reduction.

[Brief description of the drawings]

FIG. 1 is a diagram showing an 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 illustrating an example of mounting a CT.

FIG. 6 is a connection diagram illustrating an example of mounting a CT.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Primary winding 2 Secondary winding 3 Insulating resin 4 Projection part 5 Shaft conductor 6 Cylindrical conductor 7 Mounting surface 8 Groove 9 Screw seat 11 Leg part 12 Cut core 13 Band

Claims (2)

[Claims] 1. A current transformer in which a cylindrical primary winding and a secondary winding arranged on concentric circles are integrally formed of an insulating resin and an iron core is sandwiched between an outer peripheral portion and a center hole of the winding. The dimensional difference between the outer radius and the inner radius of the primary winding and the secondary winding is made larger than their axial length to form a flat cylindrical winding, and a columnar projection made of insulating resin vertically in the upper part of the main body. A shaft conductor and a cylindrical conductor are coaxially arranged at the center of the core, and their lower ends are connected to both ends of the primary winding to form primary winding connection terminals. Sink. 2. The current transformer according to claim 1, wherein a lower portion of the primary winding connection terminal portion is a large-diameter portion, an upper portion is a small-diameter portion, and a surface perpendicular to the axial direction formed on the step portion is a mounting surface. Current transformer characterized by the following.