JPS6119112A - Zero-phase current transformer - Google Patents

Abstract

PURPOSE:To facilitate the winding and assembling works as well as to reduce residual voltage by a method wherein, after the winding on a bobbin is finished, a conductor is arranged on the winding, and a EI-shaped magnetic core is installed on the bobbin. CONSTITUTION:A winding 6 is performed on an insulative square cylindrical bobbin 5, and primary conductors 7 are fixedly arranged on the winding 6 through the intermediary of an insulating material in such a manner that the end of a conductor is extended in the same direction. Besides, the center part of an E-type core 8 is inserted and fixed in the center hole from both ends of the bobbin 5, and a zero-phase current transformer is formed. By forming the current transformer as above, the winding and assembling works can be performed very easily, and residual voltage is reduced remarkably. Excellent characteristics can be obtained as a zero-phase current transformer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a zero-phase current transformer, particularly a through-type zero-phase current transformer.

[Prior art]

A feedthrough zero-phase current transformer is used as a device to detect earth leakage.

Widely used in earth leakage breakers, electric shock prevention devices, etc.

Here, a conventional through-type zero-phase current transformer will be explained with reference to FIG.

Toroidal core 1 (or seamless hollow).

Circular punched iron cores may be stacked. ) is provided with two windings (hereinafter referred to as secondary conductor) 2 using a toroidal winding machine to form an inductor. Furthermore, the inductance is molded with insulating resin (indicated by 4 in the figure), leaving the above-mentioned hollow space, and the conductor (hereinafter referred to as the primary conductor) is passed through the inductor hollow (or passed through the inductor several times). ).

In general, zero-phase current transformers are highly sensitive and can detect minute ground leakage currents, and they do not malfunction due to the effects of external induction or residual magnetic fields from the primary conductor.
Stable sensitivity characteristics with little change are required.

Therefore, in conventional zero-phase current transformers, the magnetic core (iron core)
A seamless punched iron core or rolled iron core is used.
When winding (secondary conductor) these iron cores, it is necessary to use a toroidal winding machine as mentioned above, which makes it difficult to automate the second winding and increases the cost of the second winding. Ta. Furthermore, the yield rate of the ring-shaped punched iron core is low, and therefore, the manufacturing cost of the conventional zero-phase current transformer is high.

[Purpose of the invention]

An object of the present invention is to provide a zero-phase current transformer that has the characteristics required of the above-mentioned zero-phase current transformer and that can be easily operated with two windings.

Another object of the present invention is to provide a zero-phase current transformer that is inexpensive to manufacture.

Remaining days below [Structure of the invention] According to the present invention, the coil bobbin is wound.

A zero-phase current transformer in which a plurality of conductors are arranged on the winding, the coil bobbin is arranged as a sun-shaped magnetic core, and the current flowing through the conductor is detected by the winding, wherein the conductors are connected to each other. The zero-phase current transformer is characterized in that the conductors are arranged in close contact with each other and are insulated, and the conductors are arranged in close contact with each other and are magnetically shielded, and the winding is also magnetically shielded. A zero-phase current transformer is obtained.

[Embodiments of the invention]

The present invention will be explained below based on examples.

First, with reference to FIG. 2, a winding (secondary conductor) 6 is applied to an insulating rectangular cylindrical bobbin 5, and the ends of the conductors extend in the same direction on the secondary conductor 6 as shown in the figure. with two primary conductors (
The coated conductors) 7 are arranged and fixed in close contact with each other via an extremely thin insulating material. Furthermore, the central part of the E-type iron core 8, which is made by laminating thin plate-like punched iron cores, is inserted and fixed into the center hole from both ends of the bobbin 50, thereby forming a zero-phase current transformer. The thin plate-shaped punched iron core described above is made of a magnetic material with high magnetic permeability (for example, 80 N
i-5Mo-Fe). Furthermore, a coaxial conductor 9 may be used as the primary conductor 7 as shown in FIG.

Next, referring to FIGS. 4(a), (b), and (C), the secondary conductor 6 is attached to the bobbin 5 as shown in the above embodiment.
After winding the secondary conductor 6, as shown in Fig. 4(a),
The magnetic shielding material 10 is applied so as to cover it. This magnetic shielding material 10 is an E-type iron core (
(not shown).

An open portion 101 is provided as shown in the figure so that a short circuit is not formed by the magnetic shielding material 10. When the twisted primary conductor 7 is two parallel conductors as shown in FIG. 4(b), the magnetic shielding material 11 is applied so as to wrap the conductors in close contact with each other.

The primary conductor 7 is connected to the coaxial cable 9 as shown in FIG. 4(C).
In this case, the magnetic shielding material 12 is applied (wound) on the coaxial cable 9. Note that since it is sufficient for the magnetic shielding materials 11 and 12 to shield only residual magnetism, it does not matter if a short circuit occurs. In addition, magnetic shielding ρ80 Ni
High permeability materials such as -5Mo-Fe, 45Ni-
It may also be a 4-malloy such as Fe.

The inventor manufactured various zero-phase current transformers described above using the iron core, secondary conductor, primary conductor, and magnetic shielding material shown in FIG. 5, and investigated their characteristics. The results are shown in FIG.

In Figure 6, the horizontal axis represents the reciprocating current (-order current Ir, (A)) flowing in the primary conductor of the zero-phase current transformer, and the vertical axis represents the residual voltage (EL (mV)), which is connected to the secondary conductor. Load (2
Next load resistance RL) shall be 750 ohm. Curve a is the zero-phase current transformer 2 curve shown in Figure 2, and curve C is the zero-phase current transformer 2 curve shown in Figure 3, which is the secondary conductor shown in Figures 4 (a) and (b). A zero-phase current transformer using a shielded bobbin and a shielded primary conductor (two parallel wires) are shown in Figures 4(a) and (C), respectively.
The characteristics of a zero-phase current transformer using a shielded bobbin wound with a secondary conductor and a shielded primary conductor (coaxial cable) are shown, respectively. Furthermore, curve d shows the characteristics of a conventional electric phase current transformer. As is clear from FIG. 6, the zero-phase current transformer according to the present invention has an extremely lower residual voltage than the conventional zero-phase current transformer. In other words, it was found that it has excellent characteristics as a zero-phase current transformer.

〔Effect of the invention〕

As explained above, according to the present invention, instead of having 9 windings on a bobbin, which is extremely easy to assemble, it is possible to use a structure in which one grooved body is closely arranged or magnetically shielded. With.

Since the secondary conductor is also magnetically shielded, a zero-phase current transformer with extremely low residual voltage and excellent characteristics can be obtained.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a conventional zero-phase current transformer;
The figure is a perspective view showing an embodiment of a zero-phase current transformer according to the present invention.
FIG. 3 is a perspective view showing another embodiment of the zero-phase current transformer according to the present invention, and FIGS. 4(a), (b), and (C) show parts constituting the zero-phase current transformer according to the present invention. FIG. 5 is a perspective view showing the structure covered with a magnetic shielding material, and FIG. 5 is a diagram showing the standards of the components of the zero-phase current transformer according to the present invention. FIG. 6 is a diagram showing the residual voltage characteristics of the zero-phase current transformer according to the present invention. 1... Toroidal magnetic core, 2, 6... Secondary conductor, 3,
7...1 grooved body, 4...mold, 5... is bi/, 8... KW iron core, 9... coaxial conductor, 10,1
1.12...Magnetic view Figure 1 Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] 1. Winding a coil bobbin, arranging a plurality of conductors on the winding, arranging the coil bobbin as a sun-shaped magnetic core, and detecting the current flowing through the conductor using the winding. A zero-phase current transformer 2 characterized in that the conductors are arranged in close contact with each other and are insulated. A zero-phase current transformer in which a plurality of conductors are arranged in the coil bobbin and the coil bobbin is arranged in a sun-shaped magnetic core so that the current flowing in the conductor is detected by the winding, the conductors are in close contact with each other. A zero-phase current transformer characterized in that the windings are arranged and magnetically shielded, and the windings are also magnetically shielded.