JPH06244043A - Split type current transformer - Google Patents

Abstract

PURPOSE:To prevent unnecessary magnetic fluxes caused by the effects of external electric and magnetic fields from reaching the instrument part of a split type current transformer, by providing a plurality of concentric magnetic shielding cases in each of which its halved split parts are so provided that they are engaged with each other by a spring force and they cover the instrument part. CONSTITUTION:A primary current I flowing in the earthing wire of an arrester flows through the center of an instrument part 12 of a split type current transformer, and thereby, a magnetic flux PHI passed through a core 10 is generated. By the magnetic flux PHI, an induced voltage is generated in a coil 11, and the leakage current of the arrester is sensed by a load 19 via a connection wire 18. At this time, in the path of the magnetic flux of the core 10, the magnetic flux PHI. is passed through core parts 10a wherein the core sections split by an A-A plane are engaged with each other. At this point, if unnecessary magnetic fluxes phi caused by the effects of external electric and magnetic fields are generated in the instrument part 12, first, the magnetic fluxes phi flow respectively using as their paths an outside shielding case 15 of a first stage. Therefore, the magnetic fluxes phi give no effect to the magnetic flux PHI, and the true value of the leakage current of the arrester can be sensed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a split type current transformer for measuring a minute leakage current flowing in a grounding wire of a lightning arrester, for example.

[0002]

2. Description of the Related Art FIG. 5 shows, for example, Japanese Utility Model Laid-Open No. 61-177428.
FIG. 6 is a cross-sectional plan view showing the configuration of the conventional split type current transformer disclosed in the publication, and FIG. 6 is a cross-sectional side view of FIG. In the figure, 1
a and 1b are molded insulator cases that cover the main body of the split-type current transformer, 2a and 2b are iron cores 3a and 3b, which are formed by stacking, for example, silicon-copper plates in a shape divided into semicircles.
A coil formed by winding a copper wire around each of b, 4 is a protective case interposed between the iron cores 2a, 2b and the coils 3a, 3b, and 5 is a molded insulator case 1a, 1b surrounding the coils 3a, 3b. And 6 are fillers filled between and, 6 is a bolt for tightening the engagement of the molded insulator cases 1a and 1b,
7 is a nut screwed with the bolt 6, 8 is a coil 3a, 3b
A lead wire and a lead wire 9 are connected to the lead wire 8. Here, FIG. 7 shows the iron core 2 in FIGS.
The functional diagram of coil 3a, 3b wound on a, 2b is shown.

Next, the operation will be described. For example, when the primary current I flows through the center of the split type current transformer attached to the grounding wire of the lightning arrester, a magnetic flux Φ passing through the iron cores 2a and 2b is generated, which causes a minute voltage induced in the coils 3a and 3b. Is detected by the external load 9. Iron core 2 at this time
The magnetic flux passages a and 2b penetrate the divided portion and the magnetic flux Φ penetrates. The molded insulator cases 1a and 1b, the protective case 4, and the filler 5 are constituent members for mechanically constructing this split type current transformer.

[0004]

Since the conventional split type current transformer is constructed as described above, in addition to the magnetic flux generated due to the primary current I, it is affected by an external electric field and a magnetic field, and is excessive. There is a problem that the induced voltage generated in the coil by the magnetic flux superimposed on the iron core is measured with an error with respect to the true value.

The present invention has been made in order to solve the above problems, and obtains a split type current transformer capable of measuring a minute leak current with a true value without being affected by an external electric field or magnetic field. The purpose is to

[0006]

The split type current transformer according to the present invention has a split portion which is divided into two portions, covers the measuring portion, and the split portions are concentric with each other by a spring force and are magnetically coupled to each other. It is provided in multiple.

[0007]

The split type current transformer according to the present invention prevents the magnetic flux generated by the effect of an unnecessary external electric field or magnetic field from reaching the measuring section in the shield case, and fits the split section of the magnetic shield means by the spring action. Makes the magnetic shield effective and facilitates multiple simultaneous couplings.

[0008]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is a sectional front view showing the configuration of a split type current transformer according to a first embodiment of the present invention, and FIG. 2 is a line II-- in FIG.
It is sectional drawing along II. In the figure, 10 is a laminated iron core having a divided portion 10a, 11 is a coil wound around the iron core 10, and 10 and 11 constitute a measuring portion 12.
13 is a bobbin for fixing the iron core 10 and the coil 11;
Reference numeral 4 denotes an inner shield case that covers the iron core 10 and the coil 11 and has a split portion 14a that can be split in two. One end of the split portion 14a on one side is curved 14b, and 15 is outside the inner shield case 14, The outer shield case has a split portion 15a that can be split into two split portions, and the split portion 15a
One end is curved 15b, 16 is a non-metal bobbin for fixing, 17 is an insulating pin which is penetrated to mechanically fix all of the above 12 to 16, 18 is a winding A connection line for obtaining the secondary output of this split type current transformer at the terminal of the turned coil 11, and 19 is a load connected to the coil 11 via the connection line 18 as a secondary output for detecting the leakage current of the arrester, for example. is there.

The split type current transformer constituted by the above-mentioned respective parts is constructed so as to be structurally symmetrically divided into two along the arrow A--A, that is, the iron core 10, the coil 11, the both shield cases 1.
4, 15 and the non-metal bobbins 13 and 16 are all divided by the measuring section dividing / coupling section 12a of the AA section, and the divided sections are formed so as to wrap at the dividing sections. With this structure, the iron core 10 and the coil 11 are symmetrical with respect to the divided portion AA, and the number of turns of the coil 11 is equally divided. Further, in the split portion A-A, the iron core 10 is divided into two iron cores, and the bobbin 13 is fitted to the iron core 1 so that the iron cores 10 are engaged with each other in a comb shape so that the teeth are engaged with each other.
The positions of 0 and the coil 11 in the mechanical structure are firmly fixed. Similarly, the bobbin 16 firmly fixes the position on the mechanical structure so that the divided shield cases of the inner shield case 14 and the outer shield case 15 can be easily fitted together.

Next, the operation will be described. For example, when the primary current I flowing through the grounding wire of the lightning arrester flows through the center of the measuring unit 12, a magnetic flux Φ passing through the iron core 10 is generated, thereby generating an induced voltage in the coil 11 and leaking the lightning arrestor to the load 19 via the connecting wire 18. Detect current. At this time, iron core 10
The magnetic flux Φ penetrates the iron core 10a fitted at the divided portion AA and the magnetic flux Φ penetrates. In addition to the magnetic flux Φ generated by the primary current I described above, if an unnecessary magnetic flux φ generated by the influence of an external electric field or magnetic field is generated around the measuring unit 12, the magnetic flux φ is first generated in the first stage. Since it flows through the outer shield case 15 of the eye as a passage, the true value of the lightning arrester leakage current can be detected without affecting the magnetic flux Φ passing through the iron core 10, which is required now. Further, if a part of the unnecessary magnetic flux φ penetrates through the magnetic flux protection by the outer shield case 15, the invasion of the magnetic flux φ can be blocked by the same action as described above in the second inner shield case 14, and a minute lightning arrester can be provided. Leakage current can be measured accurately.

In the above operation and action, in order to effectively prevent the influence of the unnecessary magnetic flux φ generated by the external electric field and the magnetic field by the outer shield case 15 or the inner shield case 14, each of the two divided fitting parts is provided. Must be reliably abutted to form each shield loop.
In order to deal with this, the divided portions each have a spring action in the abutting direction so that they can be fitted and brought into contact with each other, and the fitting tip has a curved shape by warping, which facilitates simultaneous joining of the divided portions. There is.

Example 2. In the first embodiment, the split type current transformer is provided with a double protective shield case of the outer shield case 15 or the inner shield case 14, and the tip of the fitting portion of each shield case is attached to the tip of the ski warp. Although it was shown that the opening and closing at the time of splitting is made smooth by bending like this, if the shield case is mechanically structured, it is more effective to make the double layer triple. Insert the slit 20 as shown in Fig. 3 into the fitting part,
Elasticity may be provided by a shield case at the time of fitting.

Embodiment 3. Further, in the first embodiment, the curvature of the warp tip is provided only on one of the inner and outer shield cases, and in the second embodiment, the slit is provided only on the outer one, but the opposite It is possible to employ the structure shown in FIG. 4 in which a curved portion is provided on the outer side of the opposite side of each outer shield case, a slit is provided on the inner side, and a combination of the inner side and the outer side is used to freely change.

[0014]

As described above, according to the present invention, since the measuring portion is covered with the two divided portions and the divided portions are fitted with each other by the spring force, a plurality of magnetic shield cases are concentrically provided. In addition, it is possible to effectively prevent the magnetic flux generated by the influence of an unnecessary external electric field or magnetic field from reaching the measuring section, and to obtain the split type current transformer in which the split coupling of the shield case can be easily operated.

[Brief description of drawings]

FIG. 1 is a sectional front view showing the configuration of a split type current transformer according to a first embodiment of the present invention.

2 is a cross-sectional view taken along the line II-II in FIG.

FIG. 3 shows a configuration of a second embodiment of the present invention, in which A is a sectional front view and B is a side view thereof.

FIG. 4 shows a configuration of a third embodiment of the present invention, in which A is a sectional front view and B is a side view thereof.

FIG. 5 is a cross-sectional plan view showing a configuration of a conventional split type current transformer.

FIG. 6 is a sectional side view of FIG.

FIG. 7 is a functional configuration diagram showing a configuration of an iron core and a coil in FIG.

[Explanation of symbols]

 10 Iron Core 10a Iron Core Dividing Part 11 Coil 12 Measuring Part 12a Measuring Part Split Joining Part 14 Inner Shield Case 14a Dividing Part 15 Outer Shield Case 15a Dividing Part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsukasa Yoneyama 2-4-1, Nishitsujigaoka, Chofu-shi, Tokyo Tokyo Electric Power Co., Inc. Technical Research Institute (72) Inventor Akira Matsumaru Nishitsutsujigaoka, Chofu-shi, Tokyo 2-4-1, TEPCO Technical Research Institute (72) Inventor Isao Kaku 8-1-1, Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric Corporation Itami Works

Claims (1)

[Claims] 1. A split type current transformer in which a measuring section for inserting a measured cable and measuring a minute leak current flowing through the measured cable has a split coupling section in a circumferential direction and is formed so as to be split into two parts. A split type current transformer characterized in that it has a split portion corresponding to two splits, covers the measurement portion, and is provided with a plurality of magnetically shielded cases concentrically fitted to each other by a spring force.