JP2001083187A - Optical current transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical current transformer wherein a conductor to be measured is taken in/out of a spool with no interference with a transfer type optical fiber. SOLUTION: A spool 3 can be circumferentialy split into halves while an opening part 12 for delivery of a conductor 1 to be measured is formed, with a pair of transfer type optical fibers 70 and 80 for light transfer connected to both ends of a Faraday effect type optical fiber 20. Here, the transfer type optical fiber 70 is wound, one round, around the spool 3, then it is folded back, with the Faraday effect type optical fiber 20 connected to its end part through a polarizer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical current transformer for measuring a current flowing through a conductor to be measured by using a Faraday effect type optical fiber in which a plane of polarization of transmitted light rotates in proportion to the strength of a magnetic field. In particular, the present invention relates to an optical current transformer that allows a conductor to be measured to enter and exit a bobbin without being disturbed by a transmission optical fiber.

[0002]

2. Description of the Related Art An optical current transformer using a Faraday effect-type optical fiber for measuring current has a similar effect to core saturation even when the current increases, as compared with a conventional current transformer in which a winding is wound around an iron core. It is characterized by the fact that the optical fiber is an insulator even if the conductor to be measured is at a high pressure, and that it is easy to insulate even if the conductor to be measured has a high voltage. There is also an advantage that the electric substation can be totally optically controlled by the optical current transformer.

FIG. 7 is a perspective view showing a configuration of a conventional optical current transformer. A Faraday effect type optical fiber 2 is wound along the outer periphery of the non-magnetized winding frame 3 composed of the winding frame portions 3A and 3B, and is input to the input end 2A of the Faraday effect type optical fiber 2 via the polarizer 4. Transmission type optical fiber 7 is connected,
An output transmission type optical fiber 8 is connected to an output end 2B of the Faraday effect type optical fiber 2 via an analyzer 5 and a condenser lens 6. The conductor 1 to be measured for current measurement passes through the inside of the bobbin 3.

In FIG. 7, a Faraday effect type optical fiber 2 has a property that the plane of polarization of light passing therethrough rotates in proportion to the strength of a magnetic field. For example, lead glass (quartz glass containing a large amount of lead oxide) is used. Is the Faraday effect type. The Faraday effect is a phenomenon in which, when light passes through lead glass or the like placed in a magnetic field, the polarization plane of the light rotates by a rotation angle θ = V · H · L. Here, V is the Verdet constant, H is the magnetic field in the light traveling direction, and L is the path length of the light. Lead glass has a Verdet constant V that is about six times as large as that of general quartz glass containing no lead oxide, and the magnetic field H
Is large, the rotation angle θ of the polarization plane of the light is large. On the other hand, the transmission type optical fibers 7 and 8 merely transmit light, and may be ordinary silica glass optical fibers containing no lead oxide or plastics optical fibers. In addition,
The above-mentioned Faraday effect type optical fiber may be used as the transmission type optical fibers 7 and 8. When the current I flows through the conductor 1 to be measured, a magnetic field H that increases and decreases in proportion to the current I is formed around the conductor I. In this state, when the incident light P1 is incident on the transmission optical fiber 7 for input, the incident light P1 is linearly polarized in one direction by the polarizer 4 and becomes light P, which is input to the input end 2A of the Faraday effect optical fiber 2. enter. When the light P passes through the Faraday effect type optical fiber 2, its polarization plane is rotated by the rotation angle θ due to the magnetic field H. The light P inclined by the rotation angle θ is output from the output end 2 of the Faraday effect type optical fiber 2.
After reaching B, the light is emitted toward the analyzer 5. Analyzer 5
Transmits only the light component of the incident light P in the direction that can pass therethrough, and the transmitted light P2 condensed by the condenser lens 6
Is emitted to the transmission optical fiber 8 for output. The amount of change in the amount of transmitted light P2 when the current I flows through the measured conductor 1 is proportional to the rotation angle θ with respect to the amount of transmitted light P2 when the current I does not flow through the measured conductor 1. The current I can be known by calculating the change in the amount of transmitted light P2. The change in the amount of the transmitted light P2 is converted into an electric signal by a converter (not shown) and output.

In the optical current transformer shown in FIG. 7, the winding frame 3 can be divided into two in the circumferential direction, and an opening is formed inside the winding frame 3 so that the conductor 1 to be measured can be put in and out. be able to. For this reason, the optical current transformer can be attached to the conductor to be measured 1 even during energization. That is, the winding frames 3A and 3B can be divided into two in the circumferential direction. The depth-side divided surfaces 3C of the winding frames 3A and 3B are linear and connected to each other via a hinge 11. on the other hand,
The division surface 3D on the front side of the winding frame portions 3A and 3B is Z-shaped and abuts each other.

FIG. 8 is a perspective view showing a configuration in which an opening 12 is formed in the winding frame 3 of FIG. The dividing surface 3D of the winding frame portions 3A and 3B is opened in the circumferential direction by the hinge 11, and an opening 12 is formed in the winding frame 3. The conductor to be measured 1 can be taken in and out of the winding frame 3 through the opening 12.
Therefore, the measured conductor 1 can be passed through the bobbin 3 while the measured conductor 1 is energized, and the current I flowing therethrough can be measured. Further, the conductor to be measured 1 can be removed from the winding frame 3. Therefore, it is not necessary to cause a power outage when measuring the current of the conductor 1 to be measured, and the optical current transformer can be relocated even in a live line.

[0007]

However, the conventional optical current transformer as described above can measure the current of the conductor to be measured without causing a power outage. There was a problem that it was difficult to do.

That is, when the conductor to be measured is put in and taken out of the bobbin, the transmission-type optical fiber for optical input / output is in the way. Since it is necessary to pass the conductor to be measured between the transmission type optical fiber for input and the transmission type optical fiber for output, if the transmission type optical fiber for optical input / output is bundled, It takes a lot of time to separate the optical fibers. For this reason, conventionally, the transmission type optical fiber for optical input / output cannot be accommodated in one pipe, and the wiring of the transmission type optical fiber cannot be compactly arranged.

It is an object of the present invention to provide an optical current transformer in which a conductor to be measured can be taken in and out of a bobbin without being disturbed by a transmission type optical fiber.

[0010]

According to the present invention, in order to achieve the above object, a conductor to be measured is a Faraday effect type optical fiber in which a plane of polarization of light passing therethrough is rotated in proportion to the strength of a magnetic field. The fiber is made to circulate along the penetrating bobbin and light is passed through the Faraday effect type optical fiber, and a signal proportional to the rotation angle of the polarization plane of the light passing through the Faraday effect type optical fiber is output. An optical current transformer for measuring a current flowing in a conductor, wherein the winding frame can be divided into two in a circumferential direction and an opening for inserting and removing a conductor to be measured can be formed, and light can be transmitted. In a current transformer in which a pair of transmission-type optical fibers are connected to both ends of the Faraday effect-type optical fiber,
It is preferable that one of the transmission type optical fibers is made to make a round along the winding frame, and then connected to the Faraday effect type optical fiber such that the direction of light is turned back. As a result, when the conductor to be measured is put in and taken out of the opening of the bobbin, the pair of transmission optical fibers is moved to one side of the opening, so that the conductor to be measured is taken out of the bobbin without being disturbed by the transmission optical fiber. Can be put in and out.

In such a configuration, the direction of the light may be folded by bending the transmission type optical fiber.

In such a configuration, the direction of light may be turned back by the prism.

In such a configuration, the direction of light may be turned back by the reflector.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. FIG. 1 is a perspective view illustrating a configuration of an optical current transformer according to an embodiment of the present invention. The transmission optical fiber 70 makes a round along the winding frame 3 and is folded at the folded portion 70A, and is connected to the Faraday effect optical fiber 20 via the polarizer 4. The incident light P <b> 1 travels around the winding frame 3 by the transmission type optical fiber 70 and then returns to the folded portion 70.
The light is turned back at 180 degrees at A, and then input to the polarizer 4. The rest of FIG. 1 is the same as the conventional configuration of FIG. In FIG. 1, the polarizer 4 and the analyzer 5 are directly fixed to the bobbin 3, respectively, but the polarizer 4 and the analyzer 5 need not necessarily be fixed to the bobbin 3. The polarizer 4 and the analyzer 5 may be pulled out to the near side as shown in FIG. 8 and the polarizer 4 and the analyzer 5 may be fixed by a support (not shown). In this case, it is sufficient that the end of the transmission optical fiber 70 that goes around the winding frame 3 is connected to the polarizer 4 drawn out toward the user. As shown in FIG. 1, the polarizer 4 and the analyzer 5 are directly wound on the winding frame 3 on the division surface 3D.
The Faraday effect type optical fiber 2
As 0 completely rotates, support for fixing the polarizer 4 and the analyzer 5 becomes unnecessary.

FIG. 2 is a perspective view showing a configuration in which an opening 12 is formed in the winding frame 3 of FIG. Since the folded portion 70A is formed, the pair of transmission optical fibers 70 and 80 can be moved to one side (left side) of the opening 12 when the conductor 1 to be measured is put in and taken out of the opening 12, and The pair of transmission optical fibers 70 and 80 does not hinder the measurement conductor 1 from being inserted into and removed from the bobbin 3. Thereby, the transmission type optical fibers 70 and 80 can be accommodated in one pipe, and the wiring of the transmission type optical fibers 70 and 80 becomes compact.

FIG. 3 is a perspective view showing a configuration of an optical current transformer according to a different embodiment of the present invention, and the folded portion 70B
Are constituted by prisms that fold the direction of light. The rest of FIG. 3 is the same as the configuration of FIG.

FIG. 4 is an enlarged sectional view showing the detailed structure of the folded portion 70B. The polarizer 4 and the condenser lens 60 are attached to the triangular prism 100, and the transmission optical fiber 70 and the Faraday effect optical fiber 20 are joined to the polarizer 4 and the condenser lens 60, respectively. Prism 100 from transmission type optical fiber 70 via polarizer 4
Is bent twice by the inclined surface of the prism 100, and the folded light P is condensed by the condenser lens 60, and then enters the Faraday effect type optical fiber 20. . As a result, the light P becomes 18
It is folded back 0 degrees.

FIG. 5 is a perspective view showing a configuration in which an opening 12 is formed in the winding frame 3 of FIG. Also in this case, since the folded portion 70B is formed, the pair of transmission optical fibers 70 and 80 does not hinder the conductor 1 to be measured from being inserted into and removed from the winding frame 3 through the opening 12. Thereby, the transmission type optical fibers 70 and 80 can be accommodated in one pipe, and the wiring of the transmission type optical fibers 70 and 80 becomes compact.

FIG. 6 is an enlarged sectional view showing the structure of the folded portion of the optical current transformer according to still another embodiment of the present invention. The folded portion 70C is merely a bent reflecting plate 101 instead of the prism 100 of FIG. 4, and the other portions of FIG. 6 are the same as those of FIG. Light P incident from the transmission optical fiber 70 via the polarizer 4 is reflected by the reflection plate 10.
The light P is bent twice by the one inclined reflection surface, and the returned light P is condensed by the condensing lens 6, and then enters the Faraday effect type optical fiber 20. The folded portion 70C is replaced with the folded portion 70B of FIGS. 3 and 5, so that the pair of transmission optical fibers 70 and 80 hinder the insertion and removal of the conductor 1 to be measured from the winding frame 3 through the opening 12. Will not be. Thereby, the transmission type optical fibers 70, 80 can be housed in one pipe, and the transmission type optical fibers 70, 80
80 wiring becomes compact.

In each of the cases shown in FIGS. 1 and 3, the folded portions 70A and 70B are provided on the transmission type optical fiber 70 side, but the transmission type optical fiber 70 from the polarizer 4 is immediately brought forward. And the transmission type optical fiber 80 is joined to the condensing lens 6 on the side opposite to the analyzer 5 through the above-mentioned folded portion, and the transmission type optical fiber 80 is wound around the bobbin 3.
After making one round clockwise along the line, it may be configured to be pulled out to the near side. Also, the pair of transmission optical fibers 70 and 80 can be moved to one side (right side) of the opening of the winding frame 3, and the pair of transmission optical fibers 70 70 and 80 do not get in the way. Thereby, the transmission type optical fiber 7
0, 80 can be accommodated in one pipe, and the wiring of the transmission type optical fibers 70, 80 becomes compact.

[0021]

According to the present invention, as described above, one of the transmission type optical fibers is made to make a round along the winding frame and then connected to the Faraday effect type optical fiber in such a manner that the light direction is turned back. In addition, the conductor to be measured can be taken in and out of the bobbin without being disturbed by the transmission type optical fiber. Therefore, a pair of transmission-type optical fibers for optical input / output can be accommodated in one pipe, and wiring of the transmission-type optical fiber is made compact.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an optical current transformer according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration in which an opening is formed in the bobbin of FIG. 1;

FIG. 3 is a perspective view showing a configuration of an optical current transformer according to another embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view showing a detailed configuration of a folded portion in FIG. 3;

FIG. 5 is a perspective view showing a configuration in which an opening is formed in the bobbin of FIG. 3;

FIG. 6 is an enlarged cross-sectional view showing a configuration of a folded portion of an optical current transformer according to still another embodiment of the present invention.

FIG. 7 is a perspective view showing a configuration of a conventional optical current transformer.

8 is a perspective view showing a configuration in which an opening is formed in the bobbin of FIG. 7;

[Explanation of symbols]

1: conductor to be measured, 2, 20: Faraday effect type optical fiber, 3: winding frame, 4: polarizer, 5: analyzer, 6, 60: condenser lens, 70A, 70B, 70C: folded portion, 7,
8, 70, 80: transmission optical fiber, 100: prism, 101: reflector, 12: opening

Claims (4)

[Claims] An optical fiber in which the polarization plane of light passing therethrough is rotated in proportion to the strength of a magnetic field is made to circulate along a winding frame through which a conductor to be measured penetrates, and light is transmitted to the Faraday effect optical fiber. An optical current transformer that outputs a signal proportional to the rotation angle of the plane of polarization of light passing through the Faraday effect type optical fiber, and measures the current flowing through the conductor under measurement from the signal, The winding frame can be divided into two parts in the circumferential direction, and an opening for taking in and out the conductor to be measured can be formed. A pair of transmission type optical fibers for transmitting light are provided at both ends of the Faraday effect type optical fiber. In each of the optical current transformers connected to the Faraday effect type optical fiber, after making one of the transmission type optical fibers make a circuit along the bobbin, the direction of light is turned back. Optical current transformer, characterized by comprising connection to. 2. The optical current transformer according to claim 1, wherein the direction of the light is folded by bending the transmission type optical fiber. 3. An optical current transformer according to claim 1, wherein the direction of the light is turned back by a prism. 4. The optical current transformer according to claim 1, wherein the direction of the light is turned back by the reflection plate.