JPH06289062A - Optical current transformer - Google Patents

Abstract

PURPOSE:To reduce in size an optical current transformer to be mounted in a gas insulated switch gear. CONSTITUTION:Elements 18a-18c having polarizers 19a-19c, analyzers 20a-20c mounted near at hand and Faraday effect are so buried as to be circulated, at conductors 12a-12c to be measured in a mold 14 of an insulation spacer 15 for supporting the elements 12a-12c in a sealed vessel 17.

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 Conventionally, a so-called through-type current transformer is used for a current transformer in a gas-insulated switchgear, in which a secondary winding is wound around an iron core and penetrates through a conductor of the gas-insulated switchgear which is a primary winding. It was However, if the through-type current transformer has a high voltage, the insulation distance between the conductor of the gas-insulated switchgear and the through-current transformer will increase, and the through-current transformer will increase in size. As a result, there is a drawback that the entire gas-insulated switchgear becomes large. Further, when an overcurrent such as a fault current flows through the conductor of the gas insulated switchgear, the through current transformer is magnetically saturated, which causes a waveform distortion.

Therefore, in recent years, a method of optically measuring an electric current by utilizing the Faraday effect has attracted attention. Such an optical current measuring device is small in size, has excellent insulation properties, can accurately measure overcurrent, and has excellent noise resistance. FIG. 2 shows an example of a conventional optical current measuring device. This is an example of measuring the current flowing through a three-phase conductor. The conductors 2a, 2b, 2c to be measured are arranged in a closed container 1 having a ground potential, and the Faraday effect elements 3a, 3b, 3c are arranged around the conductors 2a, 2b, 2c to be measured, respectively. The Faraday effect elements 3a, 3b, 3c are respectively provided with support bases 5a, 5 inside the storage cases 4a, 4b, 4c.
It is fixed via b and 5c. On the other hand, in the closed container 1, a metal container 7a for accommodating the optical heads 6a, 6b, 6c for measuring the currents of the conductors 2a, 2b, 2c to be measured,
7b and 7c are provided. The optical head 6a,
Although not shown, 6b and 6c are composed of a polarizer, an analyzer, a lens, an end face of the fiber, and the like. 8a, 8
b and 8c are optical fibers. Furthermore, the metal container 7
a, 7b, 7c are insulating cylinders 10a, 10a via flanges 9a, 9b, 9c for maintaining insulation with the closed container 1.
It is supported by b and 10c. In the conventional example configured in this way, the light emitted from the optical heads 6a, 6b, 6c propagates through the insulating cylinders 10a, 10b, 10c, enters the Faraday effect elements 3a, 3b, 3c, and is repeatedly reflected. After traveling around the conductors 2a, 2b, 2c to be measured, they propagate again in the insulating cylinders 10a, 10b, 10c,
The light is received by the optical heads 6a, 6b, 6c. 11a,
Reference numerals 11b and 11c are optical paths in the insulating cylinders 10a, 10b and 10c.

[0004]

When the current of the gas-insulated switchgear is to be measured by the optical current measuring device shown in FIG. 2, the hermetically sealed container 1 having the structure shown in FIG. 2 is newly added.
Must be added to the gas-insulated switchgear, or a part of the hermetically sealed container must have a structure as shown in FIG. 2, and in any case, the gas-insulated switchgear becomes large. Therefore, the present invention is intended to make the optical current transformer of the gas insulated switchgear smaller.

[0005]

According to the present invention, a Faraday effect element is embedded in an insulating spacer that supports a conductor of a gas insulated switchgear so as to surround the conductor.

[0006]

With the above structure, the Faraday effect element is supported by the insulator in the insulating spacer,
The insulation of the gas insulated switchgear from the closed container at the ground potential can be easily maintained. Therefore, it is not necessary to add a sealed container for the optical current transformer to the gas insulated switchgear or to modify a part thereof, and the optical current transformer of the gas insulated switchgear can be downsized.

[0007]

Embodiment An embodiment of the present invention will be described with reference to FIG. This is for measuring the current flowing through the three-phase conductor, and the measured conductors 12a, 12b, 12c are three-phase insulating spacers 15 formed by the flange 13 and the mold 14.
Is supported in a closed container 17 of ground potential filled with SF6 gas 16. Faraday effect elements 18a, 18b, and 18c are provided near the Faraday effect element 1.
Polarizer 19 for supplying linearly polarized light to 8a, 18b and 18c
a, 19b, 19c, Faraday effect elements 18a, 18
Analyzers 20a, 20b, 20c for separating the light modulated by b, 18c into P wave and S wave are installed. The Faraday effect elements 18a, 18b, 18c are installed so as to surround the conductors 12a, 12b, 12c to be measured, and the polarizers 19a, 19 are provided in the mold 14 of the insulating spacer 15.
b, 19c and analyzers 20a, 20b, 20c are embedded. 21 is a Faraday effect element 18a, 18
b is an optical fiber for supplying light to 18c and for guiding the light modulated by the Faraday effect to the outside of the closed container 17. According to the configuration as described above, the Faraday effect elements 18a, 18b, 18c are the conductors to be measured 12a, 12b, 12 measured by the mold 14 of the insulating spacer 15.
By being embedded and supported in the circumference of c, the insulation with the grounded closed container 17 can be easily maintained.

[0008]

According to the present invention, a closed container having a structure for supporting an optical transformer composed of a Faraday effect element is provided.
It is not necessary to newly add or modify the gas insulated switchgear, and the gas insulated switchgear can be downsized.

The attachment to the existing gas-insulated switchgear can be easily performed by replacing the existing spacer with the spacer according to the present invention.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, (a) is a schematic sectional view,
(B) is sectional drawing on the AA 'line of (a).

FIG. 2 is a diagram showing an example of a conventional optical current measuring device.

[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 Mold 15 Insulation spacer 16 SF6 Gas 17 Sealed container 18a, 18b, 18c Faraday Effect element 19a, 19b, 19c Polarizer 20a, 20b, 20c Analyzer 21 Optical fiber

Claims (1)

[Claims] 1. An optical current transformer having a Faraday effect element embedded in a mold of an insulating spacer for supporting a conductor to be measured in a gas-insulated switchgear so as to circulate the conductor to be measured.