JPS6317230Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a fully molded current transformer in which an annular core with an uncut structure and a secondary coil and a primary coil wound around the core are entirely molded.

Conventionally, this type of all-molded current transformer has a secondary coil wound around the entire circumference of an uncut annular core with an insulator interposed therebetween, and an insulating layer between the primary and secondary coils is provided on top of the secondary coil. The coil is also wrapped around the entire circumference, and then the whole thing is molded. This is 1
Since the inter-secondary insulating layer narrows the space in the core window in which the primary coil is to be wound, the dimensions of the core window inevitably become larger, and the finished external dimensions also become larger. Therefore, the external dimensions of the entire molded product are large, and naturally a large amount of material is required.

In addition, it has been previously proposed that the primary coil and secondary coil are separated and wound planarly around each half of the annular core. Because the coil and the secondary coil have the same number of winding stages at the core window, it is not possible to reduce the size of the core window.
Another disadvantage is that leakage magnetic flux increases.

An object of the present invention is to provide a fully molded current transformer that can solve the above-mentioned problems, have a smaller outer size, a smaller coil, and a smaller leakage magnetic flux.

In order to achieve this objective, the present invention covers only an area smaller than 1/2 of the circumference of an annular core with an uncut structure, with an insulating cylinder having flanges at both ends,
The primary coil is wound on the insulating tube so that the number of stages of the primary coil is greater than the number of stages of the secondary coil on the core window side and extends to the center of the core window, and the coil is wound over the entire length of the remaining part of the annular core. The secondary coil is wound around the iron core window, thereby increasing the space utilization rate of the iron core window, and the coil center of the primary coil is positioned closer to the center of the iron core window.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

Fig. 1 is a cross-sectional view showing the internal elements of a current transformer in one embodiment of the present invention. An insulating tube 2 is placed over an area less than half the circumference of an annular core 1 with no cuts. The insulating tube 2 has flanges 3 at both ends as shown in Fig. 2, and is divided into upper and lower halves. A primary coil 4 is wound on top of the insulating tube 2. The primary coil 4 is wound in multiple layers on the side of the core window 5, extending to the center of the core window 5, i.e., in a fan shape. The flanges 3 prevent the primary coil 4 from collapsing.

A secondary coil 7 is wound over the entire length of the remaining portion of the annular core 1 with a low voltage insulating layer 6 interposed therebetween. 2
The secondary coil 7 is wound so that the number of winding stages on the side of the core window 5 is approximately twice that on the outside of the core. The collar portion 3 of the insulating tube 2 acts as an insulator between the primary and secondary bodies.

The deformer internal elements formed as shown in FIG. 1 are molded entirely of thermoset wood to create a fully molded current transformer as shown in FIGS. 3 and 4. The outer molded body 8 is provided with a primary terminal fitting 9 and a secondary terminal fitting 10, and a mounting fitting 11 is attached to the bottom.

According to this embodiment, the primary coil 4 and the secondary coil 7 are completely separated and wound in a plane within the core window 5, and the space of the core window 5 can be narrowed as in the conventional case. Since there is no insulating layer between primary and secondary,
Moreover, since the primary coil 4 is wound in a number of stages greater than the number of stages of the secondary coil 7 on the side of the core window 5, the space usage rate of the core window 5 can be increased. Therefore, the dimensions of the iron core window 5 can be reduced, and along with this, the external dimensions can be reduced and the number of coils can be reduced.

Furthermore, the primary coil 4 is wound so that the number of stages of the primary coil 4 is greater than the number of stages of the secondary coil 7 on the core window 5 side and extends to the center of the core window 5. Assuming that the primary coil 4 of 2 is replaced with a single through conductor, the center of the coil corresponding to the position of the through conductor will be located closer to the center of the iron core window 5 (the through conductor is located closer to the center of the iron core window 5).
The leakage magnetic flux will be minimized if it is located at the center of the
Because the secondary coil 7 is distributed over 1/2 or more of the circumference of the annular core 1, and because the outer dimensions of the core window 5 and the annular core 1 are made small as described above, 1 It is possible to prevent the leakage magnetic flux caused by the secondary coil 4 from increasing and increase the coupling coefficient with the secondary coil. That is, in general, when the primary coil and the secondary coil are arranged in a plane, the leakage magnetic flux due to the primary coil increases and the coupling coefficient with the secondary coil becomes small, but according to this embodiment, , this does not occur, and therefore, the error characteristics can be made almost the same as those of conventional molded current transformers.

As explained above, according to the present invention, only an area smaller than 1/2 of the circumference of an annular core having an uncut structure is covered with an insulating cylinder having flanges at both ends,
The primary coil is wound on the insulating tube so that the number of stages of the primary coil is greater than the number of stages of the secondary coil on the core window side and extends to the center of the core window, and the coil is wound over the entire length of the remaining part of the annular core. By winding the secondary coil around the iron core window, we increased the space utilization rate of the core window and moved the center of the primary coil closer to the center of the core window, reducing the external dimensions. The coil can be made smaller, and leakage magnetic flux can be reduced.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the internal elements of a current transformer in an embodiment of the present invention, Fig. 2 is a perspective view showing an insulating cylinder in an embodiment of the invention, and Figs. 3 and 4 are FIG. 1 is a front view and a side view showing the appearance of one embodiment. 1... Annular iron core, 2... Insulating cylinder, 3... Flam part, 4... Primary coil, 5... Iron core window, 7... 2
Next coil.

Claims (1)

[Scope of utility model registration request] In a fully molded current transformer in which an annular core with an uncut structure and a primary coil and a secondary coil wound around the core are entirely molded, only an area smaller than 1/2 of the circumference of the annular core is formed. , cover an insulating tube with flanges at both ends, and place 1 on top of the insulating tube.
The secondary coil was wound so that the number of stages of the primary coil was greater than the number of stages of the secondary coil on the core window side and extended to the center of the core window, and the secondary coil was wound over the entire length of the remaining part of the annular core. A fully molded current transformer characterized by: