JPH08101234A - Photoelectric current transformer - Google Patents

Abstract

PURPOSE: To obtain a photoelectric current transformer in which a stress applied to a Faraday effect element is relaxed, in which the deviation of an optical axis is eliminated so as to perform a measurement with high accuracy and by which a gas insulated switchgear can be constituted so as to be small. CONSTITUTION: The circumference of Faraday effect elements 18a, 18b, 18c is covered with resins 20a, 20b, 20c whose elasticity is high. In addition, optical heads 21a, 21b, 21c are coupled directly to the Faraday effect elements 18a, 18b, 18c. The Faraday effect elements 18a, 18b, 18c, the optical heads 21a, 21b, 21c and a part of optical fibers 19a, 19b, 19c which are coupled directly to the optical heads are buried and installed in a resin 14 for an insulating spacer 15.

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 using the Faraday effect mounted on a gas insulated switchgear.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional optical current transformer that optically measures current using the Faraday effect. The Faraday effect elements 3a, 3b, 3c are arranged so as to surround the conductors under test 2a, 2b, 2c arranged in the closed container 1 at the ground potential via the support bases 5a, 5b, 5c and the storage case 4a.
It is fixed to 4b and 4c. On the other hand, the optical head 6a,
6b and 6c are housed in metal containers 7a, 7b and 7c, and optical fibers 8a, 8b and 8c for optical signal propagation are provided.
Are directly connected. The metal containers 7a, 7b, 7c are
It is directly fixed to the closed container 1, and like the closed container 1,
It is ground potential. The storage cases 4a, 4b, 4c
Through the flanges 9a, 9b, 9c, the insulating cylinder 10
a, 10b, 10c, metal containers 7a, 7b, 7c
Is fixed to the conductors 2a, 2b, 2c and the storage cases 4a, 4b, 4c close to the conductors 2a, 2b, 2c, and the metal containers 7a, 7b, 7c at the ground potential are electrically insulated. Further, 11a, 11b, 11c are insulating cylinders 10a,
Optical paths 10b and 10c, and conductors to be measured 2a and 2
b, 2c and the storage cases 4a, 4b, 4c close to the conductors 2a, 2b, 2c to be measured, and to maintain insulation between the metal containers 7a, 7b, 7c and the closed container 1 which are at ground potential. , Spatial transmission. Optical head 6
The optical signals emitted from a, 6b, and 6c are isolated by the insulating tube 10.
a, 10b, 10c are propagated in the optical paths 11a, 11b, 11c, are incident on the Faraday effect elements 3a, 3b, 3c, and are repeatedly reflected in the Faraday effect elements 3a, 3b, 3c, and the conductor to be measured 2a is measured. 2b and 2c, the light propagates in the optical paths 11a, 11b and 11c again and is received by the optical heads 6a, 6b and 6c.

[0003]

However, the above-mentioned optical current transformer for the gas-insulated switchgear of FIG. 2 has the following drawbacks. The Faraday effect elements 3a, 3b, 3c include mechanical stress such as vibration of the gas insulated switchgear, the Faraday effect elements 3a, 3b, 3c, and the Faraday effect element 3
The stress caused by the difference in linear expansion coefficient from the support bases 5a, 5b, 5c for supporting a, 3b, 3c is applied, and the optical signal is distorted in the Faraday effect elements 3a, 3b, 3c, causing the measurement error. Becomes When a conventional optical current transformer for a gas-insulated switchgear is attached, a sealed container 1 having a structure as shown in FIG. 2 is newly added, or a part of the sealed container of the gas-insulated switchgear is replaced with the one shown in FIG. It is necessary to change to the structure as shown in, and in any case, the gas-insulated switchgear becomes large. The measured conductors 2a, 2b, 2c and storage cases 4a, 4b, 4 close to the measured conductors 2a, 2b, 2c.
c and the metal containers 7a, 7b, 7c at ground potential and the closed container 1 to maintain electrical insulation, the optical heads 6a, 6b, 6c and the Faraday effect elements 3a, 3b,
3c is a space transmission, the alignment of the optical axis between them is difficult and the assembly becomes complicated, and the mechanical stress such as the vibration of the gas insulated switchgear and each component forming the optical current transformer The optical axis shift due to the stress caused by the difference in the linear expansion coefficient causes a loss of the optical signal, which causes a measurement error. Therefore, the present invention provides an optical current transformer that relieves the stress applied to the Faraday effect element, can perform high-precision measurement by eliminating the deviation of the optical axis, and can configure the gas insulated switchgear in a small size. It is in.

[0004]

[Means for Solving the Problem] The periphery of a Faraday effect element is covered with a highly elastic resin, the optical head and the Faraday effect element are directly connected, and the Faraday effect element and the optical head are directly connected to the optical head. A part of the optical fiber is embedded in the resin of the insulating spacer that holds the conductor to be measured.

[0005]

Since the Faraday effect element is covered with the highly elastic resin, the stress applied to the Faraday effect element can be relieved. Since the Faraday effect element, the optical head, and part of the optical fiber directly connected to this optical head are embedded in the resin of the insulating spacer that holds the conductor to be measured of the gas insulated switchgear, the gas insulated switchgear is attached at the time of installation. There is no need to add or change a closed container to the gas insulated switchgear, and the gas insulated switchgear can be downsized as compared with the case where a conventional optical current transformer is attached. Further, even if the optical head and the Faraday effect element are directly connected, it is possible to electrically insulate between the conductor to be measured and the closed container having the ground potential, and by the direct connection between the optical head and the Faraday effect element, Positioning of the optical axis between the optical head and the Faraday effect element is facilitated to facilitate assembly, and the optical axis shift due to stress is eliminated, resulting in no loss of optical signals.

[0006]

1 is an example of an optical current transformer for a gas insulated switchgear according to the present invention. Faraday effect element 18a, 18
b, 18c around the high elastic resin 20a, 20b,
20c and covered with Faraday effect elements 18a, 1
8b, 18c and the optical heads 21a, 21b, 21c are directly connected, and further, the Faraday effect element 18a,
18b and 18c are conductors 12a, 12b and 12c to be measured.
Faraday effect elements 18a, 18b, 18c and optical heads 21a, 2 so as to be positioned so as to orbit
1b, 21c and the optical heads 21a, 21b, 21
A part of the optical fibers 19a, 19b, 19c directly connected to c is embedded in a resin 14 having a good electrical insulation property. The insulating spacer 15 is composed of the resin 14 and the flange 13, and
It is fixed in a closed container 17 filled with F6 gas 16. As the highly elastic resins 20a, 20b, 20c, for example,
An epoxy-based or silicone-based resin can be used, and as the resin 14, an epoxy-based resin can be used.

Thus, the Faraday effect element 18a,
Highly elastic resin 20a, 20 around 18b, 18c
Since it is covered with b and 20c, the Faraday effect element 18
Since the stress applied to a, 18b, and 18c is relaxed and the Faraday effect elements 18a, 18b, and 18c are directly connected to the optical heads 21a, 21b, and 21c, the optical axis deviation between them is eliminated and the measurement accuracy is improved. . Furthermore, these Faraday effect elements 18a, 18b, 18
c, the optical heads 21a, 21b, 21c and a part of the optical fibers 19a, 19b, 19c directly connected to the optical heads 21a, 21b, 21c, the measured conductor 12a,
Resin 14 of insulating spacer 15 holding 12b, 12c
Since it is embedded in the inside, the optical current transformer can be made compact. Further, this makes it possible to reduce the size of the gas insulated switchgear as compared with the case where a conventional optical current transformer is attached.

[0008]

As described above, according to the present invention, the stress applied to the Faraday effect element is relieved, and the optical axis deviation between the Faraday effect element and the optical head is eliminated, so that highly accurate measurement can be performed. Moreover, since the optical current transformer can be made compact, the gas insulated switchgear can be made compact.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an optical current transformer for a gas insulated switchgear according to the present invention, in which (a) is a plan view and (b) is a cross-sectional view taken along the line AA of the plan view (a). .

FIG. 2 is a diagram showing an example of a conventional optical current transformer for a gas-insulated switchgear.

[Explanation of symbols]

 1 airtight container 2a, 2b, 2c measured conductor 3a, 3b, 3c Faraday effect element 4a, 4b, 4c storage case 5a, 5b, 5c support base 6a, 6b, 6c optical head 7a, 7b, 7c metal container 8a, 8b , 8c Optical fiber 9a, 9b, 9c Flange 10a, 10b, 10c Insulation cylinder 11a, 11b, 11c Optical path 12a, 12b, 12c Measured conductor 13 Flange 14 Resin 15 Insulation spacer 16 SF6 Gas 17 Sealed container 18a, 18b, 18c Faraday Effect element 19a, 19b, 19c Optical fiber 20a, 20b, 20c Resin 21a, 21b, 21c Optical head

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H02B 13/02

Claims (1)

[Claims] 1. An optical transformer for measuring a current flowing through a conductor to be measured by utilizing a Faraday effect received by light passing through the inside of the Faraday effect element by penetrating a conductor to be measured in a central portion of the Faraday effect element. In the sink, while covering the periphery of the Faraday effect element with a highly elastic resin, the Faraday effect element and the optical head are directly connected, and further, the Faraday effect element and the optical head, and the optical fiber directly connected to the optical head. An optical current transformer for a gas-insulated switchgear, part of which is embedded in the resin of the insulating spacer that holds the conductor to be measured.