JPH06230039A - Optical fiber current sensor - Google Patents

Abstract

PURPOSE:To eliminate the stress of an optical fiber at both ends of a middle point piece by providing a bobbin on which an optical fiber is wound around and formed with a middle point receiving recessed part to receive the middle point piece. CONSTITUTION:A bobbin 3 is formed into a cylindrical shape having a hollow part 5 for passing electric wire 4 therethrough, an optical fiber 1 is wound therearound and a middle point receiving recessed part 6 to receive a middle point piece 2 is formed thereon. Errors due to winding the optical fiber 1 around the bobbin 3 and the like are decreased by rotating the point piece 2 so as to twist the optical fiber 1. Further, because the point piece 2 is received in the receiving recessed part 6, the optical fiber at both ends of the point piece 2 is not floated up from the bobbin 3, and hence can be smoothly laid along the surface of the bobbin 3. Consequently, stress of the fiber at both ends of the point piece 2 can be eliminated. Thereby, the main factor of errors due to stress is eliminated, errors as an optical fiber current sensor are decreased, so that the accuracy can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber current sensor for detecting a current flowing in an electric line such as a power transmission line by using an optical fiber having a magneto-optical effect.

[0002]

2. Description of the Related Art A conventional example is shown in FIGS. That is, the optical fiber current sensor includes a single mode optical fiber 30 having a magneto-optical effect, and the optical fiber 30.
A middle point piece 31 that is a jig that is provided in the middle part of the optical fiber 30 and can twist the optical fiber 30, and a bobbin 33 that is a tubular shape having a hollow portion 34 through which the electric wire 32 is passed and that is wound with the optical fiber 30. I have it.

When a current flows through the electric wire 32, a magnetic field is generated in the longitudinal direction of the optical fiber 30 around the electric wire 32. A light emitting unit (not shown) is connected to one end of the optical fiber 30 via a polarizer (not shown), and the optical fiber 30 is polarized (linearly polarized).
When the incident light is incident, the plane of polarization rotates at a rotation angle proportional to the magnetic field. When a light receiving section is connected to the other end of the optical fiber 30 via an analyzer and the light whose polarization plane is rotated is incident on the analyzer, light having an intensity proportional to the rotation angle of the polarization plane is emitted and is received by the light receiving section. It Since the strength of the magnetic field is proportional to the magnitude of the electric current, the light receiving section can receive the light having the strength proportional to the magnitude of the electric current, so that the magnitude of the electric current can be detected.

Although an error occurs in the output signal due to the bending of the optical fiber 30 when the optical fiber 30 is wound around the bobbin 33, the middle point piece 31 is turned to rotate the optical fiber 3
It can be reduced by twisting 0.

[0005]

However, in this optical fiber current sensor, stress is applied to the optical fiber 30 because the optical fibers 30 at both ends of the middle point piece 31 are lifted from the bobbin 33 by the radius of the middle point piece 31. This stress has been a cause of error in the photocurrent sensor.

Therefore, an object of the present invention is to provide an optical fiber current sensor capable of removing stress on the optical fibers at both ends of the middle point piece.

[0007]

An optical fiber current sensor according to a first aspect of the present invention includes an optical fiber having a magneto-optical effect, and a middle point piece provided in an intermediate portion of the optical fiber and capable of twisting the optical fiber. And a bobbin having a hollow portion through which an electric wire is passed, the bobbin having a hollow portion for accommodating the optical fiber and accommodating the middle point piece.

[0008]

According to the optical fiber current sensor of the present invention, when a current flows through the electric wire, a magnetic field is generated in the longitudinal direction of the optical fiber around the electric wire. When polarized light enters the optical fiber from one end side, the polarization plane rotates due to the magneto-optical effect of the optical fiber itself and emerges from the other end side. The current is detected by passing the light through an analyzer and detecting the intensity. Further, an error caused by winding the optical fiber around a bobbin can be reduced by rotating the middle point piece and twisting the optical fiber. In this case, since the middle point piece is stored in the middle point storing recess, the optical fibers at both ends of the middle point piece can be laid along the surface of the bobbin from the bobbin without lifting from the bobbin. The stress can be removed, and therefore, the error factor caused by the stress can be removed, and the error as the photocurrent sensor can be reduced and the accuracy can be improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. That is, this optical fiber current sensor has an optical fiber 1, a middle point piece 2, and a bobbin 3. The optical fiber 1 is an example of a single-mode optical fiber.

The middle point piece 2 is provided in the middle portion of the optical fiber 1 so that the optical fiber 1 can be twisted.
In the embodiment, one middle point piece 2 is provided at the center of the optical fiber 1 in the longitudinal direction. The middle point piece 2 has an outer diameter such that it can be pinched, has a through hole for the optical fiber 1 in the center thereof, and penetrates the optical fiber 1 through the through hole and is fixed by an adhesive. Therefore, an error factor caused by bending the optical fiber 1 such as being wound around the bobbin 3 is adjusted by eliminating the error by rotating the middle point piece 2.

The bobbin 3 has a cylindrical shape having a hollow portion 5 through which the electric wire 4 is inserted, and forms a middle point accommodating recess 6 for accommodating the optical fiber 1 and accommodating the middle point piece 2. The depth of the middle point storage recess 6 is about the radius of the middle point piece 2. In this optical fiber current sensor, when a current flows through the electric wire 4, a magnetic field is generated in the longitudinal direction of the optical fiber 1 around the electric wire 4. When polarized light enters the optical fiber 1 from one end side, the polarization plane rotates due to the magneto-optical effect of the optical fiber 1 itself and emerges from the other end side.
The current is detected by passing the light through an analyzer and detecting the intensity. Further, an error caused by winding the optical fiber 1 around the bobbin 3 can be reduced by rotating the middle point piece 2 and twisting the optical fiber 1.

According to this embodiment, the middle point piece 2
Since the optical fiber 1 at both ends of the middle point piece 2 can be licked along the surface of the bobbin 3 without being lifted from the bobbin 3, since it is stored in the middle point storage concave portion 6, The stress can be removed, and therefore, the error factor caused by the stress can be removed, and the error as the photocurrent sensor can be reduced and the accuracy can be improved.

A second embodiment of the present invention is shown in FIGS.
Shown in. That is, this optical fiber current sensor has a hole 6a for accommodating the middle point piece 2 in the main body 3a of the bobbin 3.
The soft plate 3b formed with is wound around the main body 3a to form the middle point storage recess 6. Others are the same as those in the first embodiment.

[0014]

According to the optical fiber current sensor of the present invention, since the middle point piece is accommodated in the middle point accommodating recess, the optical fibers at both ends of the middle point piece do not float up from the bobbin and follow the surface of the bobbin. Since the stress can be removed at both ends of the middle point piece, the error factor caused by the stress can be eliminated, and the error as the photocurrent sensor can be reduced, and the accuracy can be improved. .

[Brief description of drawings]

FIG. 1 is a plan view of a first embodiment of the present invention.

FIG. 2 is a front view thereof.

FIG. 3 is a perspective view of the appearance.

FIG. 4 is an exploded perspective view of a second embodiment.

FIG. 5 is a perspective view with a soft plate attached.

FIG. 6 is a plan view of a conventional example.

FIG. 7 is a front view of the extended state of the optical fiber before winding.

[Explanation of symbols]

 1 optical fiber 2 middle point piece 3 bobbin 4 electric wire 5 hollow part 6 middle point storage recess

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Yoshida 47 Umezu Takaune-cho, Ukyo-ku, Kyoto City, Nissin Electric Co., Ltd. (72) Inventor Ken Kawakatsu 47 Umezu Taka-une-cho, Ukyo-ku, Kyoto City

Claims (1)

[Claims] 1. A tubular shape having an optical fiber having a magneto-optical effect, a middle point piece provided in an intermediate portion of the optical fiber and capable of twisting the optical fiber, and a hollow portion through which an electric wire is passed. An optical fiber current sensor, comprising: a bobbin around which an optical fiber is wound and a middle point housing concave portion for housing the middle point piece is formed.