JPH07234252A - Optical current measuring device - Google Patents

Abstract

PURPOSE:To provide an optical current measuring device whose measuring accuracy is enhanced. CONSTITUTION:A plurality of cylindrical, metallic tanks 1 are joined together via flanges provided at the end of each tank 1, and a current-carrying conductor 2 is disposed along the axis of the metallic tanks l, and the tanks 1 are each filled with an insulating gas and a current that the current-carrying conductor 2 carries is measured by detecting the polarized state of light passing through an optical fiber 11 going around the current-carrying conductor 2. A cylindrical shield 17, disposed in such a way as to allow the current-carrying conductor 2 to pass through it, and having a flange at its end that is joined between the metallic tank flanges, is provided inside each metallic tank 1, and an insulating or nonmagnetic ring-shaped member is disposed between the outer surface of the cylindrical shield 17 and the inner surface of each metallic tank 1 via a cushioning material 18 in such a way as to surround the current- carrying conductor 2. A groove circling the outer peripheral surface of the ring-shaped member is provided and the optical fiber 11 is secured in the groove, with the end of the optical fiber 11 connected to predetermined optical equipment provided outside the tanks 1, and the ring-shaped member is held in place via an elastic member 20 disposed between the ring-shaped member and the inner surface of each metallic tank 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current measuring device for gas insulated electrical equipment, and more particularly to an optical current measuring device using an optical fiber.

[0002]

2. Description of the Related Art FIG. 2 shows a cross-sectional configuration diagram of a conventional optical current measuring device. The GIS or gas-insulated busbar is composed of a tank 1 filled with an insulating gas and a conductor 2 supported by an insulating spacer 3. In order to detect the current flowing through the conductor 2, a Faraday element 4 such as lead glass or an optical fiber having the Faraday effect is circulated so as to surround the current flowing through the conductor 2 to form an optical path. In Figure 2, Faraday
The effective optical fiber 4 is fixed to the tank 1 by the holding material 5 and the insulating material 6, and the photoelectric conversion unit 9 and the operation output unit 10 are installed outside the tank of the airtight terminal 8 penetrating the tank 1. The end portion of the optical fiber 4 is connected to a polarizer 12 and an analyzer 13 to transfer light. It should be noted that the optical fiber 4 is collected by winding a plurality of times and is supported by the holding material 5 by the retainer 7.

Next, the operation will be described with reference to the optical path diagram shown in FIG. The light emitted from the light emitting diode 14 of the photoelectric conversion unit 9 passes through the airtight terminal 8 through the optical fiber 11 for transmitting and receiving light and enters the polarizer 12 arranged inside the tank 1 to be linearly polarized. . This light enters the optical fiber 4, and the light whose polarization plane is rotated by the magnetic field created by the current flowing through the conductor 2 is incident on the analyzer 13. The light that is split into vector light of two right-angled components (X, Y components) by the analyzer 13 becomes a light amount signal and returns to the photoelectric conversion unit 9 again, and is converted into an electric signal by the photodiode 15 and then calculated. The output unit 10 calculates to obtain a current value.

[0004]

[Problems to be Solved by the Invention] However, GIS
In the conventional optical current measuring device applied to the phase or gas insulated bus, when the optical fiber 4 is used as the Faraday element, there is an essential problem as described below, which causes a measurement error.

When linearly polarized light is incident on the Faraday element,
The Faraday effect causes the plane of polarization to rotate in proportion to the magnetic field. The optical CT, which is one type of optical measuring device, measures the current from this rotation angle, so that the disorder of the polarization causes an error. An extinction ratio is one measure of the degree of polarization disorder, and is indicated by the ratio of circularly polarized light / non-polarized light components to linearly polarized light. In general, an anisotropic medium has two optical axes with different refractive indexes, which is called birefringence. An optically isotropic medium such as glass also becomes anisotropic when stress is applied to generate birefringence. This birefringence is a main factor that deteriorates the extinction ratio of the medium, and thus affects the measurement accuracy of the optical CT.

In comparison with the conventional configuration example, in FIG. 2 in which the lead glass of the Faraday element is replaced with the optical fiber 4 as it is, the optical fiber 4 is partially stressed by the retainer 7 to increase the birefringence. . With this holding method, the generation of stress due to the transmitted vibration and impact cannot be avoided. Further, there is a risk that the optical box and the optical path that are housed in the polarizer / analyzer connected to the optical fiber 4 may cause optical axis shift due to vibration or the like, or the optical fiber 4 may shake to generate bending stress. On the other hand, if the optical system such as the optical fiber 4 is exposed in the tank 1, there is a problem that the optical fiber 4 is subjected to thermal stress due to heat generated by the conductor 2 or the like.

The present invention has been proposed in order to solve the above-mentioned problems of the prior art, and its object is to provide an optical current measuring method which improves the measurement accuracy of the current flowing through the current-carrying conductor of the gas-insulated equipment. To provide a device.

[0008]

According to the present invention, a plurality of cylindrical metallic tanks are joined via flanges provided at the end portions of the tanks, and a current-carrying conductor is provided in the axial direction of the metallic tanks. An optical system in which the tank is filled with an insulating gas and the energizing current of the energizing conductor is measured by detecting the polarization state of the light passing through the optical fiber that surrounds the energizing conductor. Type current measuring device,
A tubular shield having a flange joined to the metallic tank flange at the end is disposed inside the metallic tank so that the current-carrying conductor can be inserted therethrough. An insulating or non-magnetic annular member is disposed between the outer side surface and the inner side surface of the metallic tank so as to circulate the current-carrying conductor, and a groove is provided around the outer peripheral surface of the annular member. An optical fiber is arranged and fixed in the groove, and the end of the optical fiber is connected to a predetermined optical device provided outside the tank, and the annular member is arranged between the inner surface of the metallic tank and the annular member. It is characterized by being fixed via an elastic member.

[0009]

With the above configuration, the optical fiber having the Faraday effect is wound and fixed on the insulating or non-magnetic annular member having the winding groove on the circumferential surface. There is nothing to receive. Moreover, since the cylindrical shield and the annular member are fixed via the cushioning material,
There is no longer any risk of stress on the optical fiber due to vibration or shock transmitted from the tank. In addition, by filling the inside with an elastic material, a seismic resistance effect is produced for the entire optical path in the tank, and since it functions as a heat shielding material, there is an effect of suppressing thermal stress of the optical fiber due to temperature change. Therefore, it is possible to overcome the problem that the birefringence increases due to the stress and the measurement accuracy is lowered.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an optical current measuring device for GIS constructed by using an optical fiber 4 as a Faraday element. The optical fiber 4 is provided with a storage groove on the circumferential surface of a ring-shaped bobbin 16 and is spirally wound and fixed a plurality of times. In the embodiment shown in FIG. 1, the optical fiber 4 is bonded or filled and held with silicon rubber in the groove, and is covered with a protective cover 21, and a polarizer 12 and an analyzer are provided at one end thereof.
The optical box containing 13 etc. is fixed and assembled with the bobbin 16. The bobbin 16 uses nonmagnetic aluminum or an insulator.

The bobbin 16 is fixed to the metallic tank 1 by first inserting a cushioning material 18 into a cylindrical shield 17 used for electric field relaxation, inserting the bobbin 16 up to the stepped portion, and then dividing the cushion. This is done by assembling the material 18 and the shield 17 and then attaching the shield 17 to the tank 1.

As the optical fiber 4, a single mode optical fiber having the Faraday effect is used, and a coil having a number of turns adapted to the detection sensitivity is formed. The end of the optical fiber 4 is connected to the above-mentioned optical box, and the optical box and the airtight terminal 8 are connected to each other by using an optical fiber 11 for transmission and an optical connector. The cross-sectional view of FIG. 1 shows just the location where the optical box and the airtight terminal 8 are arranged. However, at this position of the bobbin 16, the optical fibers 4 and 11 are often routed, so a part of the bobbin 16 is divided by the enclosing material 19. The elastic material 20, for example, silicon foam is filled and held.

The optical path configuration of FIG. 1 is the same as the conventional optical path diagram described in FIG. Next, the operation and effect brought about by this embodiment will be described. Put the optical fiber 4 in the bobbin 16,
The problem of partial stress was solved because it was bonded in the groove with elastic silicone rubber. Also, make sure that the vibration and shock from the tank 1 do not affect the optical fiber 4 and the optical box.
It was fixed via a shield 17 and a cushioning material 18. Further, by partitioning the optical box and a part of the periphery of the airtight terminal 8 and filling them with a foam material, a seismic resistance effect such as vibration and a heat insulating effect can be obtained. Since the optical components can be shielded from the conductor 2 that is a heat source when energized and the tank 1 that transmits the influence of the outside air temperature and sunshine, the temperature difference that affects the optical fiber 4 can be reduced and the generation of stress can be suppressed. The problems of optical axis shift and birefringence due to the temperature difference of parts are solved.

As a result, it is possible to solve the problem that the birefringence is increased by the stress and the accuracy is lowered. The above-mentioned gist of the present invention is shown in FIG.
It is also applicable to the configuration in which the cushioning material 18 shown in 1 is combined with those having different hardnesses (spring constants) and the bobbin 16 is made to have the same electric potential as the tank 1 by using a metallic member.

[0015]

As described above, according to the present invention, it is possible to provide an optical current measuring device in which the measurement accuracy of the current flowing through the current-carrying conductor of the gas-insulated equipment is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a main part of an optical current measuring device according to an embodiment of the present invention.

FIG. 2 is a sectional configuration diagram of a conventional optical current measuring device.

FIG. 3 is an optical path example solution diagram of an optical current measuring device.

[Explanation of symbols]

 1 ... Tank 2 ... Conductor 4 ... Optical fiber 5 ... Retaining material 8 ... Airtight terminal 11 ... Optical fiber 12 ... Polarizer 13 ... Analyzer 16 ... Bobbin 17 ... Shield 18 ... Buffer material 19 ... Enclosure material 20 ... Elastic material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyotoshi Terai No. 2 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Stock Company Toshiba Hamakawasaki Plant (72) Masao Takahashi No. 2 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 1 in stock company Toshiba Hamakawasaki factory (72) Inventor Keiko Niwa No. 2 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Stock company Toshiba Hamakawasaki factory

Claims (1)

[Claims] 1. A plurality of tubular metallic tanks are joined together through flanges provided at the end portions of the tanks, and a current-carrying conductor is arranged in the axial direction of the metallic tanks. In the optical current measuring device, which is filled with an insulating gas, and measures the energizing current of the energizing conductor by detecting the polarization state of the light passing through the optical fiber circulating around the energizing conductor, the metal A cylindrical shield having a flange joined to the metallic tank flanges at the end of the cylindrical tank, the outer surface of the cylindrical shield being provided so that the current-carrying conductor can be inserted therethrough. And an insulating or non-magnetic annular member is disposed between the inner side surface of the metallic tank so as to circulate the current-carrying conductor via a cushioning material, and a groove that circulates the outer peripheral surface of the annular member is provided.
An optical fiber is arranged and fixed in the groove, and the end of the optical fiber is connected to a predetermined optical device provided outside the tank, and the annular member is arranged between the inner surface of the metallic tank and the annular member. An optical current measuring device characterized in that it is fixed via an elastic member.