JP2000228323A - Rogowski coil - Google Patents

Abstract

(57) [Summary] [Problem] To prevent external magnetic field from affecting current measurement,
To provide Rogowski coils that realize high-precision current measurement. A printed circuit board (7) having an opening (9) in the center.
A front surface metal foil 2a and a back surface metal foil 2b are formed on the front surface and the back surface, respectively. The front surface metal foil 2a and the back surface metal foil 2b are each formed by a plurality of straight lines extending radially about the center of the opening 9. The front surface metal foil 2a and the back surface metal foil 2b form the winding 2 by being electrically connected by a plated through hole 2c penetrating the printed circuit board 7a. A printed board 7b, which is mirror-image-symmetric with the printed board 7a, is arranged and fixed such that the central axes of the openings 9 coincide with each other, and the respective windings 2 are connected in series.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Rogowski coil used for measuring the value of a current supplied to a transmission and substation equipment.

[0002]

2. Description of the Related Art In general, a through-type current transformer is often used to measure an alternating current supplied to a transmission / transformation device or the like. A conventional through-type current transformer is a current transformer in which a secondary winding is wound around an annular core and a conductor through which a primary current to be measured flows is passed through an opening in the center of the core. Such current transformers include those using an iron core as the winding core and those using a non-magnetic material. Of these, those using non-magnetic materials are called air-core current transformers or Rogowski coils,
Excellent linear characteristics without saturation can be obtained.

FIG. 8 shows the structure of a general Rogowski coil. A Rogowski coil 1 shown in FIG.
From the point Q to the point Q, and the return line 3 is returned along the winding core from the point Q to the point R in a direction opposite to the direction in which the winding 2 advances. Normally, the return line 3 is returned between the winding core 6 and the winding 2. The conductor 5 penetrates through the opening 6 a of the core 6.

At this time, a voltage is generated between the terminals 4 and 4 in proportion to the magnitude of the temporal change of the primary current supplied to the conductor 5. Therefore, the primary current can be measured by integrating this voltage and multiplying by a constant determined by the shape of the coil. In the case of an ideal Rogowski coil, the voltage between the terminals 4 and 4 is not affected by a deviation between the conductor 5 and the center position of the winding core 6 or a magnetic field outside the Rogowski coil.

Here, the ideal Rogowski coil is
(A) The winding interval (pitch) of the winding 2 is constant,
(B) The area surrounded by the winding 2 and the area surrounded by the return line 3 are equal, (c) the cross-sectional area of the winding core 6 is constant over the entire circumference, and is not affected by temperature, and (d) It refers to a Rogowski coil having such characteristics that the winding 2 is completely wound around the entire circumference of the winding core 6 and has no missing portion.

However, when a Rogowski coil as shown in FIG. 8 is manufactured, it is necessary to realize the above condition (a), that is, to wind the winding 2 around the winding core 6 while maintaining a constant winding interval. Technically difficult. By providing a groove or a projection on the core 6 for fixing the position of the winding 2, a constant winding interval can be maintained. However, a special core and a winding device are required for this purpose. The price of the coil becomes extremely expensive.

A conventional technique for solving this problem is disclosed in Japanese Unexamined Patent Publication No.
It is disclosed in 176947. FIG. 9 shows a configuration of a Rogowski coil disclosed in the publication. In the Rogowski coil shown in the figure, metal foils are formed on both surfaces of a printed circuit board 7 having an opening 9 at the center so as to coincide with a plurality of straight lines radiating from the center of the opening 9. Further, the radial metal foil on one surface of the printed circuit board 7 and the radial metal foil on the opposite surface are electrically connected by a plated hole penetrating the printed circuit board 7, so that the windings 2 and Return line 3 is formed. In the example shown in FIG. 9, the return line 3 also forms a winding, thereby increasing the output voltage between the terminals 4 and 4 per unit current and unit frequency, and improving the sensitivity of the Rogowski coil. The winding direction is clockwise for the winding 2 and counterclockwise for the return line 3.

According to such a conventional technique, a Rogowski coil in which the winding interval between the winding 2 and the return line 3 is accurately constant can be manufactured at low cost by applying a general printed circuit board manufacturing technique. be able to. Therefore, the above condition (a) can be realized to a considerable extent.

[0009]

In the above-mentioned conventional Rogowski coil, the above condition (b), that is, the condition that the area enclosed by the winding 2 and the area enclosed by the return line 3 are completely equal, is completely satisfied. Can not be satisfied,
It is easily affected by an external magnetic field, which causes an error in current measurement to increase.

FIG. 10 shows a state in which a winding 2 of a general Rogowski coil 1 as shown in FIG.
FIG. 5 is a schematic diagram showing a state where a magnetic flux Φ due to an external magnetic field in a direction penetrating through the holes interlinks. FIG. 11 is a schematic diagram showing a state where the magnetic flux Φ due to the same external magnetic field is linked to the return line 3 of the general Rogowski coil 1 as shown in FIG.

The terminals 4 and 4 of the Rogowski coil 1 shown in FIG.
Since the winding direction of the winding 2 and the winding direction of the return line 3 are opposite to each other, the voltage generated between the points 4 shown in FIG.
It is equal to the difference between the voltage generated between -Q and the voltage generated between points QR shown in FIG. Here, for example, assuming that the magnetic flux Φ due to the external magnetic field is uniform over the entire surface of the Rogowski coil 1, the area A surrounding the winding 2 in FIG.
And the area B surrounding the return line 3 in FIG. 11 is not equal, a voltage is generated between the terminals 4 and 4 due to the external magnetic field. This voltage is irrelevant to the primary current to be measured, and causes a measurement error.

Usually, the magnetic flux Φ due to the actual external magnetic field is not uniform, so the effect is further complicated.
By making the area A surrounding the winding 2 and the area B surrounding the return line 3 equal, more preferably, by making the shape of the winding 2 and the return line 3 exactly the same, errors can be reduced. Becomes possible.

In the Rogowski coil 1 shown in FIG. 8, it is particularly difficult to manufacture the coil while keeping the area surrounding the return line 3 constant. In the Rogowski coil shown in FIG. 9, the area surrounded by the return line 3 is smaller than the area surrounded by the winding 2. Therefore, in any case, the external magnetic field is affected.

The factors that cause an external magnetic field include the following. For example, as shown in FIG. 12, when the conductor 5 has a bend, or when the conductor 8 that is energized exists outside the Rogowski coil 1, or
As shown in FIG. 13, this is the case where the conductor 5 is arranged obliquely with respect to the Rogowski coil 1. When the Rogowski coil 1 is applied to an actual transmission / transformation device, it is impossible to completely eliminate the above-mentioned factors. There was a problem that was difficult.

The present invention has been proposed in order to solve the above-mentioned problems of the prior art. The object of the present invention is to solve the problem even when an external magnetic field penetrating through the opening at the center of the winding core exists. An object of the present invention is to provide an inexpensive Rogowski coil capable of preventing an external magnetic field from affecting current measurement and capable of measuring current with high accuracy.

[0016]

According to a first aspect of the present invention, there is provided a printed circuit board having an opening at the center thereof, the printed circuit board being provided on both sides thereof with the center of the opening substantially at the center. A plurality of metal foils are formed radially, and the metal foil on one side and the metal foil on the other side are electrically connected by plated holes passing through the printed board in the thickness direction. A first printed circuit board on which one winding is formed, and a second printed circuit board configured to be mirror-image-symmetric with the first printed circuit board. The first printed circuit board and the second printed circuit board And the printed circuit boards are arranged and fixed so that the central axes of the respective openings coincide with each other, and the windings formed on the respective printed circuit boards are connected in series.

According to the first aspect of the present invention, the winding of the first printed circuit board corresponds to the winding 2 of the conventional Rogowski coil shown in FIG. The winding corresponds to the conventional return line 3. In addition, since the two windings are in a mirror image relationship, even when an external magnetic field penetrates the central opening of the printed circuit board, the external magnetic field links the two magnetic fluxes Φ in common. Accordingly, since the voltages generated in the two windings by the magnetic flux Φ cancel each other, it is possible to prevent the external magnetic field from affecting the current measurement. Therefore, the Rogowski coil according to the present invention enables highly accurate current measurement.

According to a second aspect of the present invention, in the first aspect of the present invention, there is provided an electronic device for processing a signal induced in the Rogowski coil between the first printed board and the second printed board. A third printed circuit board provided with a circuit is closely fixed.

According to the second aspect of the present invention, the first and second printed circuit boards substantially forming Rogowski coils, and the electronic circuit for processing signals guided to them are provided. The close connection makes connection easy, and enables a low-cost Rogowski coil system including an electronic circuit. Further, since the wiring between the Rogowski coil and the electronic circuit is eliminated, an induced voltage due to an external magnetic field is not generated in the wiring portion, and the influence of the external magnetic field can be further reduced.

According to a third aspect of the present invention, there is provided a printed circuit board having an opening at the center, and a plurality of metal foils are formed on both surfaces of the printed circuit board in a radial manner with the center of the opening being substantially at the center. The metal foil on one side and the metal foil on the other side are electrically connected by a plated hole penetrating the printed board in the thickness direction, so that the printed board on which one winding is formed is formed. A circumferential metal foil having a center substantially at the center of the opening is formed in an inner layer of the printed board, and the circumferential metal foil is connected in series to the winding to return. It is characterized in that a line is formed.

According to the third aspect of the present invention, the radius of the circumferential metal foil may be determined so that the area surrounding the winding and the area surrounding the return line are equal. The return route can be easily manufactured at an accurate position by using a simple printed circuit board manufacturing technology. Therefore, when there is an external magnetic field in the direction penetrating the central opening of the printed circuit board, the area surrounded by the winding and the area surrounded by the return line are equal. The voltages generated on the return line and the return line, respectively, have substantially the same magnitude and opposite polarities, and are almost cancelled. For this reason, an external magnetic field can be prevented from affecting the current measurement, and a Rogowski coil can be provided which enables highly accurate current measurement.

According to a fourth aspect of the present invention, there is provided a printed circuit board having an opening in the center, wherein a plurality of metal foils are radially provided on both sides and two inner layers, respectively, with the center of the opening substantially at the center. Formed on one side, the metal foil and the 2
Between the metal foil of the adjacent inner layer of the layers, and between the metal foil of the other surface and the metal foil of the adjacent inner layer of the two layers, respectively, the printed board in the thickness direction. A printed circuit board on which two windings having a mirror image relationship with each other are formed by being electrically connected by plated through holes, wherein the two windings are connected in series; I have.

According to the fourth aspect of the present invention, one of the windings corresponds to the winding 2 of the conventional Rogowski coil shown in FIG. 8, and the other winding corresponds to the conventional return line. This corresponds to 3. Further, since the two windings have a mirror image relationship, even when an external magnetic field penetrates the central opening of the printed circuit board, the magnetic flux Φ at which the two windings are linked by the external magnetic field is common. . Therefore, the voltages generated in the two windings by the magnetic flux Φ cancel each other out, so that the external magnetic field can be prevented from affecting the current measurement.

According to a fifth aspect of the present invention, in the first, third or fourth aspect of the present invention, a plurality of the printed circuit boards are provided, and the printed circuit boards are arranged such that the central axes of the respective openings coincide with each other. It is characterized in that the windings fixed on the respective printed circuit boards are connected in series.

According to the fifth aspect of the present invention, the output voltage per unit current / unit frequency, that is, the output voltage per unit current / frequency, while maintaining the relationship that the area enclosed by the winding and the area enclosed by the return line are equal, is maintained. The sensitivity of the Rogowski coil can be adjusted. Therefore, an output voltage at a level suitable for processing in the electronic circuit can be easily obtained while preventing the external magnetic field from affecting the current measurement.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a Rogowski coil according to the present invention will be described below with reference to the drawings.

[1. First Embodiment] [1-1. Configuration] FIG. 1 is a perspective view showing a configuration of a Rogowski coil according to the present embodiment. In the figure, the Rogowski coil according to the present embodiment has an opening 9 in the center.
A front surface metal foil 2a and a back surface metal foil 2b are formed on a front surface and a back surface of a printed circuit board 7a having the following.
The front metal foil 2a and the rear metal foil 2b are electrically connected by plated through holes 2c penetrating the printed circuit board 7a. The printed circuit board 7a is formed by the front surface metal foil 2a, the back surface metal foil 2b, and the through hole 2c.
One winding 2 is formed thereon. Furthermore, the terminal ends of the winding 2 are drawn out as terminals 4 and 4.

A printed board 7b, which is mirror-symmetrical to the printed board 7a, is arranged and fixed so that the central axes of the openings 9 of the printed boards 7a and 7b coincide with each other, and is formed on the printed boards 7a and 7b. Connected windings are connected in series. That is, the winding 2 on the printed board 7a is connected to the conventional winding 2 shown in FIG. 8, and the winding not shown on the printed board 7b is connected to the conventional return line 3 shown in FIG.

FIG. 2 is an external view of the printed circuit board 7a in FIG. 2, the front surface metal foil 2a is indicated by a solid line, and the back surface metal foil 2b is indicated by a broken line. Front metal foil 2a and back metal foil 2b
Are each formed in a plurality of linear shapes that extend radially around the center of the opening 9. Although the printed circuit board 7b is not shown, it is a mirror image of the printed circuit board 7a shown in FIG.

[1-2. Operation and Effect] According to the Rogowski coil according to the present embodiment having the above configuration,
The following operational effects can be obtained. That is, the opening 9
When a primary current is passed through a conductor (not shown),
As in the conventional case, a voltage proportional to the magnitude of the temporal change of the primary current is generated between the terminals 4 and 4.

As shown in FIG. 12 or FIG. 13, when the conductor has a bend, when the conductor exists outside the Rogowski coil, or when the conductor is arranged obliquely with respect to the Rogowski coil. As in the case, for example, due to the arrangement of the Rogowski coil, the central opening 9
There is a case where an external magnetic field in a direction penetrating through is present. In such a case, a common magnetic flux Φ links the winding 2 on the printed board 7a and the winding (not shown) on the printed board 7b. Therefore, the voltages generated in the two windings by the magnetic flux Φ have the same magnitude and opposite polarities, and can be completely canceled.

As described above, according to the present embodiment, it is possible to effectively prevent the voltage between the terminals 4 and 4 from being affected by the external magnetic field. Rogowski coils can be provided.

[2. Second Embodiment] [2-1. Configuration] FIG. 3 is a perspective view showing a configuration of a Rogowski coil according to the present embodiment. The Rogowski coil shown in the figure is provided between the printed circuit boards 7a and 7b in the first embodiment shown in FIGS.
c is sandwiched and fixed in close contact. The printed circuit board 7c has an electronic circuit (not shown) for processing a signal induced in the Rogowski coil. Printed circuit board 7
Between the a and 7b and the printed circuit board 7c, the respective boards are electrically connected directly by means such as solder or a connector without using wiring.

[2-2. Operation and Effect] According to the present embodiment having the above configuration, the following operation and effect can be obtained. That is, the signal induced in the Rogowski coil formed by connecting the windings on the printed boards 7a and 7b in series is directly guided to the printed board 7c and integrated by an electronic circuit (not shown) on the printed board 7c. Processing is performed. Thereby, the waveform of the primary current is reproduced.

As described above, according to the present embodiment, in addition to the effects obtained in the first embodiment, the printed circuit board 7 on which the Rogowski coil is substantially formed is provided.
Since a and 7b and the electronic circuit for processing signals are close to each other, the connection between the Rogowski coil and the electronic circuit is easy, and the entire system of the Rogowski coil including the electronic circuit is configured at low cost. The effect that it can be obtained is obtained. Further, since the wiring between the Rogowski coil and the electronic circuit is eliminated, an induced voltage due to an external magnetic field is not generated in the wiring portion, and the influence of the external magnetic field can be further reduced.

[3. Third Embodiment] [3-1. Configuration] FIG. 4 is a perspective view showing a configuration of a Rogowski coil according to the present embodiment. In the figure, the Rogowski coil according to the present embodiment has an opening 9 in the center.
A front surface metal foil 2a and a back surface metal foil 2b are formed on the front surface and the back surface of the printed circuit board 7 having. Further, the front surface metal foil 2a and the back surface metal foil 2b are electrically connected by the through holes 2c. One winding 2 is formed on the printed circuit board 7 by the front metal foil 2a, the rear metal foil 2b, and the through hole 2c.

In the inner layer 12 substantially at the center in the thickness direction of the printed circuit board 7, a circumferential metal foil 3a centering on the center of the opening 9 is formed. The circumferential metal foil 3 a is connected in series to the winding 2 at a point Q so as to be a return line to the winding 2.

FIG. 5 is an external view of the printed circuit board 7 in FIG. 4 as viewed from the center axis direction of the opening 9. In FIG. 5, the front metal foil 2a is indicated by a solid line, the back metal foil 2b is indicated by a broken line, and the circumferential metal foil 3a is indicated by a two-dot chain line.
The front surface metal foil 2a and the back surface metal foil 2b are each formed in a plurality of linear shapes that radially extend around the center of the opening 9. Also, the circumferential metal foil 3 on the inner layer 12 of the printed circuit board 7 is set so that the area surrounded by the winding 2 and the area surrounded by the circumferential metal foil 3a which is the return line are equal.
The radius of a is determined. In addition, it is possible to manufacture the winding 2 and the circumferential metal foil 3a at sufficiently accurate positions by using a general printed circuit board manufacturing technique.

[3-2. Operation and Effect] According to the present embodiment having the above-described configuration, by appropriately determining the radius of the circumferential metal foil 3a, the area surrounding the winding 2 and the area surrounding the return line can be easily determined. Can be set to be equal. Further, since the area surrounded by the winding 2 is equal to the area surrounded by the return line, when an external magnetic field in a direction penetrating the central opening 9 of the printed circuit board 7 exists, the magnetic flux Φ due to the external magnetic field interlinks. The voltages generated in the winding 2 and the return line are almost equal in magnitude and opposite in polarity, so that the voltages are almost cancelled.

Therefore, according to the present embodiment, it is possible to effectively prevent the voltage between the terminals 4 and 4 from being affected by an external magnetic field, and to provide a Rogowski coil for realizing highly accurate current measurement. Can be provided.

[4. Fourth Embodiment] [4-1. Configuration] FIG. 6 is a perspective view showing a configuration of a Rogowski coil according to the present embodiment. The Rogowski coil shown in the figure is a printed circuit board 7 having an opening 9 in the center.
A metal foil is formed on each of the substrate front surface 11a and the substrate back surface 11b, and the substrate inner layers 12a and 12b that substantially divide the printed circuit board 7 in the thickness direction. These four layers of metal foil are formed in a plurality of linear shapes that extend radially about the center of the opening 9.

Then, the surface metal foil 2 on the substrate surface 11a
a and the radial metal foil (not shown) on the adjacent substrate inner layer 12a, and between the radial metal foil (not shown) on the substrate back surface 11b and the radial metal foil (not shown) on the adjacent substrate inner layer 12b, respectively. They are electrically connected by the through holes 2c. As a result, two windings having a mirror image relationship with each other are formed. Further, these two windings are connected in series similarly to the two windings in the first embodiment described above.

[4-2. Operation and Effect] According to the Rogowski coil according to the present embodiment having the above configuration,
The following operational effects can be obtained. That is, the opening 9
When there is an external magnetic field in a direction that penetrates through the windings, the external magnetic field causes the magnetic flux Φ linking the two windings in a mirror image relationship to be common. Accordingly, the voltages generated in the two windings by the magnetic flux Φ have the same magnitude and opposite polarities, and thus are completely canceled.

As described above, according to the present embodiment, the effect of an external magnetic field can be effectively prevented, so that a Rogowski coil realizing highly accurate current measurement can be provided.

[5. Fifth Embodiment] [5-1. Configuration] FIG. 7 is a perspective view showing a configuration of a Rogowski coil according to the present embodiment. The Rogowski coil shown in the figure is provided with a plurality of printed boards 7 used in the above-described first, third or fourth embodiment, and these are connected to the central axis of the central opening 9 of each printed board 7. Are fixed in close contact with each other. Each of the printed circuit boards 7, 7,... Is configured to be connected in series.

[5-2. Operation and Effect] According to the present embodiment having the above configuration, the outputs of the respective printed circuit boards 7 are added, and the output voltage per unit current / unit frequency is
It appears twice as many as the number of printed circuit boards 7.

Therefore, according to the present embodiment, the output voltage per unit current / unit frequency is maintained while maintaining the relationship that the area surrounded by the winding and the area surrounded by the return line are equal.
That is, the sensitivity of the Rogowski coil can be adjusted. Therefore, it is possible to provide a Rogowski coil that can easily obtain an output voltage suitable for processing in an electronic circuit while preventing an external magnetic field from affecting current measurement.

[0048]

As described above, according to the present invention,
Even if there is an external magnetic field that penetrates the central opening of the Rogowski coil, by applying general printed circuit board manufacturing technology, the electromotive force due to the external magnetic field can be offset inside the Rogowski coil. Therefore, it is possible to prevent the external magnetic field from affecting the current measurement.
Therefore, a Rogowski coil realizing highly accurate current measurement can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a Rogowski coil according to a first embodiment of the present invention.

FIG. 2 is a front view showing a configuration of a printed circuit board 7a according to the embodiment.

FIG. 3 is a perspective view showing a configuration of a Rogowski coil according to a second embodiment of the present invention.

FIG. 4 is a perspective view showing a configuration of a Rogowski coil according to a third embodiment of the present invention.

FIG. 5 is a front view showing the configuration of the printed circuit board 7 according to the embodiment.

FIG. 6 is a perspective view showing a configuration of a Rogowski coil according to a fourth embodiment of the present invention.

FIG. 7 is a perspective view showing a configuration of a Rogowski coil according to a fifth embodiment of the present invention.

FIG. 8 is a front view showing the configuration of a conventional general Rogowski coil.

FIG. 9 is a front view showing a configuration example of another conventional Rogowski coil.

FIG. 10 is a schematic diagram illustrating a state in which an external magnetic field is interlinked with the winding in the Rogowski coil shown in FIG. 8;

11 is a schematic diagram illustrating a state in which an external magnetic field is linked to the return line in the Rogowski coil shown in FIG. 8;

FIG. 12 is a diagram illustrating an example of a factor that causes an external magnetic field.

FIG. 13 is a view for explaining another example of a factor for generating an external magnetic field.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Rogowski coil 2 ... Winding 2a ... Surface metal foil 2b ... Backside metal foil 2c ... Through-hole 3 ... Return line 3a ... Circular metal foil 4 ... Terminal 5 ... Conductor 6 ... Core 7, 7a, 7b, 7c: printed circuit board 9: opening 11a: substrate surface 11b: substrate back surface 12, 12a, 12b: substrate inner layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Takashi Nakajima 2-1 Ukishima-cho, Kawasaki-ku, Kawasaki-ku, Kawasaki-shi, Kanagawa F-term in the Toshiba Hamakawasaki Plant (reference) 4E351 BB10 BB33 CC06 GG09 5E081 AA05 BB03 DD30 EE11 FF20

Claims (5)

[Claims] 1. A printed circuit board having an opening in the center, on both surfaces of which a plurality of metal foils are formed radially about the center of the opening, respectively, and the metal foil on one surface is A first printed circuit board on which one winding is formed by electrically connecting the metal foil on the other surface with a plated hole penetrating the printed circuit board in the thickness direction; A first printed circuit board and a second printed circuit board configured to be mirror-image symmetrical, wherein the first printed circuit board and the second printed circuit board are arranged such that the central axes of the respective openings coincide with each other. A Rogowski coil, wherein the windings fixed to the respective printed circuit boards are connected in series. 2. A third printed circuit board provided with an electronic circuit for processing a signal induced by the Rogowski coil is tightly fixed between the first printed circuit board and the second printed circuit board. The Rogowski coil according to claim 1, wherein: 3. A printed circuit board having an opening in the center, on both surfaces of which a plurality of metal foils are formed radially about the center of the opening, respectively, and the metal foil on one side is formed. A printed circuit board on which one winding is formed by being electrically connected to the metal foil on the other surface by a plated hole penetrating the printed circuit board in the thickness direction; In the inner layer, a circumferential metal foil having a center substantially at the center of the opening is formed, and the circumferential metal foil is connected in series to the winding to form a return line. Rogowski coil characterized by that. 4. A printed circuit board having an opening at the center, wherein a plurality of metal foils are formed radially about the center of the opening on both surfaces and two inner layers, respectively, and one surface is provided. Between the metal foil and the metal foil of the adjacent inner layer of the two layers, and between the metal foil of the other surface and the metal foil of the adjacent inner layer of the two layers, respectively. A printed circuit board having two windings formed in a mirror image relationship with each other by being electrically connected by plated holes penetrating the printed circuit board in the thickness direction, wherein the two windings are connected in series Rogowski coil characterized by being made. 5. A printed circuit board comprising a plurality of printed circuit boards, wherein the printed circuit boards are arranged and fixed so that the central axes of respective openings coincide with each other, and the windings respectively formed on the respective printed circuit boards are connected in series. The Rogowski coil according to claim 1, 3 or 4, which is connected.