JP3344526B2 - Zero-phase current transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zero-phase current transformer used for an earth leakage breaker.

[0002]

2. Description of the Related Art FIG. 6 shows an example of a conventional structure of a zero-phase current transformer (hereinafter referred to as ZCT) used for an earth leakage breaker, and FIG. 6 shows an example of a configuration of an earth leakage breaker using the ZCT shown in FIG. FIG. In FIG. 6, a ZCT 8 has an iron core 10 formed by laminating ring-shaped ferromagnetic plates, a secondary winding 9 wound around the iron core 10, and a thin rod shape for drawing both ends of the secondary winding 9 to the outside. The terminal 11 is housed in a resin case 12, and the resin is injected into the case 12 and solidified to integrally form all the constituent members.

Further, in the earth leakage breaker shown in FIG. 7 incorporating the ZCT having the above structure, the main circuit conductor 4 extending from the power supply terminals U and W to the load terminals R and T is composed of the primary conductor 4c of the ZCT 8.
, Except for the wiring pattern of the printed board 3. In the main circuit from ZCT8 to a load not shown,
Alternatively, if a one-line ground fault occurs in the load, this ground fault
The detection signal is detected on the secondary side of T8, the detection signal is input to the amplifier 1 and amplified, and the output of the amplifier 1 operates the relay 2 to cut off the main circuit.

[0004] In this circuit breaker configuration, the primary conductor 4c of the ZCT 8 is formed in an inverted U shape, straddles the iron core 10 of the ZCT 8, and is connected to the power supply side main circuit and the load side main circuit of the ZCT 8.

[0005]

This type of earth leakage circuit breaker is a mass-produced model, and it is desired that the circuit breaker be manufactured at a low cost by reducing the total amount of work in the process flow. There is a need to reduce the number of parts. However, in the above-mentioned conventional earth leakage breaker, it is necessary to prepare a ZCT and a primary conductor which require production of several types of components and integration of the components.

An object of the present invention is to provide a ZCT in which the number of components to be prepared individually, including the primary conductor, is reduced as much as possible.

[0007]

In order to solve the above-mentioned problems, according to the present invention, a ZCT is provided in which a primary conductor and a secondary conductor are formed by a wiring pattern of a printed board. Shall be. Specifically, as described in claim 2, the wiring pattern forming the primary conductor is formed on one or both sides of the printed board in a linear pattern that is entirely parallel to each other, and the wiring pattern forming the secondary conductor is formed. Is 1
It is preferable that a spiral pattern is formed on both sides or one side of the whole phase of the next conductor and on one side or both sides of the printed board.

When the wiring patterns of the primary conductor and the secondary conductor are formed on both sides of the printed circuit board, the patterns on both sides are preferably connected through through holes. Alternatively, as described in claim 4, the wiring pattern forming the primary conductor is formed by a through hole, and the wiring pattern forming the secondary conductor is formed at each vertex position of a zigzag path surrounding all the phases of the through hole. The formed through-holes may be formed in a coil-shaped pattern while being sequentially connected by a pattern on the front side and a pattern on the back side of the printed board.

[0009]

First, in the present invention, it is assumed that the primary conductor of the ZCT is within a length range that contributes to inducing a voltage between the terminals of the secondary conductor. Therefore, when the primary conductor and the secondary conductor of the ZCT are formed by a wiring pattern of a printed circuit board as described in claim 1, the primary conductor and the secondary conductor are formed.
The secondary conductor can be formed in the same manufacturing process as the main circuit conductor of the earth leakage breaker, and the fixing of these conductors in the earth leakage breaker except for the iron core is completed at the same time. That is, except for the iron core, there is no need to manufacture individual members as in the conventional ZCT or to integrate these members, so that the ZCT can be formed inexpensively.

[0010] As a specific wiring pattern for forming the primary conductor and the secondary conductor, as described in claim 2,
The wiring pattern that forms the secondary conductor is formed on one or both sides of the printed board in a linear pattern that is completely parallel to each other,
Assuming that the wiring pattern forming the secondary conductor is formed in a spiral pattern on both sides or one side of all the phases of the primary conductor and on one side or both sides of the printed board, the ZCT is formed by dividing the iron core into two parts. Thus, the ZCT can be completed only by penetrating the center position of the spiral pattern on the printed circuit board, and the ZCT can be formed extremely inexpensively.

When the linear pattern of the primary conductor and the spiral pattern of the secondary conductor are formed on both sides of the printed circuit board, the linear pattern conductors on both sides of the primary conductor are connected in parallel. When the thickness of the pattern conductor is constant, the area occupied by the printed circuit board surface required to pass the same main circuit current can be reduced.
The area occupied by T on the substrate surface can be reduced. In addition, since the required number of turns is obtained on both sides of the printed circuit board for the secondary conductor, the number of turns can be significantly changed within a small area of the printed circuit board. This facilitates the formation of a ZCT that widely corresponds to the above.

In the case where the linear pattern of the primary conductor and the spiral pattern of the secondary conductor are formed on both sides of the printed circuit board, through holes are used to connect the pattern conductors on both sides. Then, Z on the printed circuit board
The total occupation area or spread of the CT can be reduced. Through holes are used to connect pattern conductors on both sides of the printed circuit board. First, a conductive layer is formed by electroless plating on the inner surface of the hole formed through the printed board, then electrolytic plating is performed, and the thickness of the conductive layer is And constitute a part of the wiring pattern.

In addition, instead of forming the primary conductor and the secondary conductor of the ZCT with the pattern described in claim 3, the wiring pattern for forming the primary conductor is formed by through holes. At the same time, the wiring pattern forming the secondary conductor is connected to the through-holes formed at the apexes of the zigzag path surrounding all the phases of the through-holes in the form of a coil while connecting the front-side and back-side patterns of the printed board in order. If the zigzag path is formed, the number of coil turns can be changed widely by the distance between adjacent vertices in the zigzag path. The detection sensitivity can be changed widely.

[0014]

1 to 3 show a first embodiment of the present invention. The power supply terminals U and W to the load terminals R and
The main circuit conductor 4 reaching T includes the primary conductor 4a of ZCT and is formed by a printed circuit board wiring pattern over the entire length. 1
The secondary conductor 4a is formed in a linear pattern having two phases parallel to each other and having the same length as the width of the iron core 6, and the secondary conductors 5 are formed in a spiral pattern on both sides thereof. In the present embodiment, the spiral pattern is formed by connecting straight lines in two perpendicular directions in order so as to closely surround the iron core 6 having a rectangular cross section and reduce the occupied area. FIG. 5 shows the principle of ground fault detection using this pattern configuration.

In FIG. 5, two straight lines on both sides of the central two parallel primary conductors respectively represent a spiral pattern electromagnetically coupled with the primary conductor 4a in FIG. in the normal state without ground fault, (the direction from the power supply side terminal of the earth leakage breaker to the load side terminal positive and negative in the opposite direction) each phase of the primary conductor current I _r, the sum of I _t is zero _{(I r + I t = 0} ), the electromagnetic coupling electromotive force (V) is the I _r + I _t = 0, is not induced voltage on both sides of the secondary conductor. However, one-line ground fault (leakage) in main circuit
If occurs, although ground-fault current in the primary conductor of the direction which resulted in 1 line ground (Ig) flows, since the sound towards the primary conductor without ground-fault current flows, I _r + I _t + Ig = Ig, an electromagnetic coupling electromotive force V = R · ig is generated, and a voltage is induced in the secondary conductors on both sides. The product of the secondary current and the input impedance R of the amplifier 1 (FIG. 1) is used as an input signal voltage. It is provided to the amplifier 1.

An iron core 6 penetrating the printed board at the center of the spiral pattern forming the secondary conductor 5 (FIG. 1)
As shown in FIG. 2, a U-shaped iron core 6a formed by laminating U-shaped ferromagnetic plates and an I-shaped iron core 6b formed by laminating strip-shaped ferromagnetic plates are provided. 6a are inserted into the holes of the printed board, and the I-shaped iron core 6b is inserted into the U-shaped iron core 6b.
A closed magnetic path is formed by contacting the open end of a.

FIG. 3 is a perspective view of the entire structure inside the earth leakage breaker in which the ZCT is formed as described above. Conventional structure Z
It can be seen that the number of parts is smaller than that of the one equipped with CT and that the whole is neat. FIG. 4 shows a second embodiment of the present invention. This embodiment is similar to the first embodiment in that the primary conductor 2
While the secondary conductor is formed by the wiring pattern of the printed board, the leakage detection by the secondary conductor is performed so that the magnetic flux due to the leakage current passing through the primary conductor penetrates the printed board vertically in the first embodiment. This shows an example of the pattern configuration of the primary conductor and the secondary conductor when the generation is performed in parallel with the printed circuit board. In this embodiment, a through hole is formed in the printed board in order to generate a magnetic flux due to the leakage current in parallel with the printed board. The main circuit on the power supply side of the ZCT is formed by a wiring pattern on the back surface of a printed circuit board, the main circuit on the load side is formed by a wiring pattern on the surface of a printed circuit board, and the main circuits on both sides are connected via through holes. To the primary conductor 4
b. The number of the through holes is the same as the number of phases of the main circuit. In this embodiment, two through holes are formed. The through holes 7a forming the secondary conductor 7 at each vertex position of the zigzag path along the circumference surrounding the two through holes are formed. As shown in FIG. 4B, the back surface and the front surface of each through hole 7a are connected in a pattern in the direction of the zigzag path in this order, whereby the secondary conductor is formed in a coil shape. I have.

The detection sensitivity of the ZCT according to this embodiment is determined by the cross-sectional area of the formed coil, the number of turns, the radius of curvature of the zigzag path, and the like.

[0019]

According to the present invention, the ZCT used for the earth leakage breaker is
Has the above structure, the following effects can be obtained. In the structure of the first aspect, since the primary conductor and the secondary conductor of the ZCT are formed by the wiring pattern of the printed board, these conductors can be formed simultaneously in the step of forming the conductors other than these conductors by the wiring pattern. And the number of parts to be individually manufactured for ZCT formation is greatly reduced.
T can be made inexpensively.

According to the second aspect of the present invention, the wiring pattern forming the secondary conductor is spirally formed on both sides or one side of the primary conductor all-phase package formed linearly by the pattern and on one side or both sides of the printed circuit board. Since it is formed, the number of turns can be changed widely within a small area of the printed circuit board surface, and a ZCT can be obtained that can widely correspond to a required value of a minimum leakage current at which the leakage breaker can be cut off.

In the structure of the third aspect, the patterns on both sides of the printed board are connected to each other through through holes.
The total occupied area or spread of the ZCT on the printed board can be reduced, and the size of the earth leakage breaker can be avoided. In the structure of claim 4, the secondary conductor of ZCT is
The zigzag path is formed in a coil shape by using the through holes formed at each vertex position of the zigzag path surrounding the same number of through holes as the number of phases of the main circuit forming the primary conductor. Depending on the number, the required leakage detection sensitivity can be widely and easily dealt with.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of an internal configuration of an earth leakage breaker having a ZCT according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a core structure of the ZCT shown in FIG. 1;

FIG. 3 is a perspective view of the earth leakage breaker shown in FIG. 1;

FIG. 4 is a plan view showing an example of an internal configuration of an earth leakage breaker having a ZCT according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing the principle of earth leakage detection by the ZCT shown in FIG.

FIG. 6 is a diagram showing a structural example of a conventional ZCT.
(A) is an external plan view, (b) is a cross-sectional view.

7A and 7B show an example of the internal configuration of the earth leakage breaker provided with the ZCT shown in FIG. 6, wherein FIG. 7A is a plan view and FIG.

[Explanation of symbols]

 Reference Signs List 3 printed board 4 main circuit conductor 4a primary conductor 4b primary conductor 5 secondary conductor 6 iron core 7 secondary conductor 7a through hole 8 ZCT

Claims (4)

(57) [Claims] 1. A zero-phase current transformer of an earth leakage breaker for detecting a ground fault current flowing through a primary conductor, wherein the primary conductor and the secondary conductor are formed by a wiring pattern of a printed board. And zero-phase current transformer. 2. The wiring pattern according to claim 1, wherein the wiring pattern forming the primary conductor is formed in a linear pattern parallel to each other on one side or both sides of the printed board, and the wiring pattern forming the secondary conductor is formed. A zero-phase current transformer characterized in that the pattern is formed in a spiral pattern on both sides or one side of the primary conductor all-phase package and on one or both sides of the printed board. 3. The printed wiring board according to claim 2, wherein when the wiring patterns of the primary conductor and the secondary conductor are formed on both sides of the printed board, the patterns on both sides are connected through through holes. Zero-phase current transformer. 4. The zigzag track according to claim 1, wherein a wiring pattern forming a primary conductor is formed by a through hole, and a wiring pattern forming a secondary conductor is formed in a zigzag path surrounding all phases of the through hole. A zero-phase current transformer, characterized in that a through-hole formed at each apex position is connected to a front side and a back side of a printed circuit board in a sequential pattern to form a coil-shaped pattern.