JPS60207067A - Gas insulating three-phase current transformer - Google Patents

Abstract

PURPOSE:To make it possible to exclude the influence of the magnetic field of other phase by detecting only the intensity of a magnetic field of each phase itself, by using a magneto-optical element generating a Faraday rotary angle by the intensity of the magnetic field present only in a light passing direction. CONSTITUTION:One continuous optical magnetic field sensor 18 formed into a yarn like form lead glass having flexibility is wound around the periphery of each of conductors 2u-2w at least once and this lead glass generates a Faraday rotary angle by the intensity of a magnetic field present only in the optical axis direction of a light path. A hermetically sealed terminal 7 is provided to a position in close vicinity to the optical magnetic field sensor 18 of each phase on a tank 1. When light is sent from a light emitter LED through this hermetically sealed terminal 7, light is incident to a Faraday element through a polarizer and an 1/4 wavelength plate and converted to oval polarized light corresponding to the magnitude of the magnetic field. Then, this light is returned to the hermetically sealed terminal 7 through a light detector and received by a light receiver PD while a signal proportional to the magnitude of the magnetic field is outputted from an operator OP.

Description

[Detailed Description of the Invention] [Technical Field of the Invention 1] The present invention relates to a current transformer used in a three-phase integrated type gas-insulated switchgear, and in particular relates to a current transformer used in a three-phase integrated type gas-insulated switchgear, and in particular to a magneto-optic field transformer having a magneto-optical effect. This relates to a current transformer constructed by

[Technical Background of the Invention] Conventionally, a gas-insulated three-phase current transformer used in a three-phase all-in-one type gas-insulated closed stomach is an iron-core type current transformer made by winding a coil around a steel plate. = It was composed of Ia.

An example of such a conventional gas-insulated three-phase current transformer will be illustrated and explained in FIG. Inside the cylindrical tank 1, three-phase conductors 2 (''~2w) of U, \/, and W phases are arranged.Tank 1
An insulating slide 3 is installed before and after the tank 1, and a J:'C conductor 2(''~2w) is supported on this.
It is divided into front and rear parts perpendicular to its axis, and consists of a tank 1a located at the front having the original diameter, and a tank 1b located at the rear having a diameter increased by the dimension of the current transformer core 4.

A current transformer core is sterilized on each of the extensions of the conductors 2u-2w at the inner end of the tank 1b. A support plate 5 is installed in front of the current transformer core 4 (that is, at the end of the rear tank 1b), and is connected to the inside of the current transformer core 4 (which is connected to an insulating shield 6). These support the current transformer core 4 and insulate it from the conductor 2 (~2W).Furthermore, at the bottom of the tank 1, there is a A sealed terminal 7 for drawing out is provided.

By the way, in such a gas-insulated three-phase current transformer, three
Because the current transformer core installed at the location is heavy, the support plate, insulation shield, etc. that support it are also quite large, and these are
Because the equipment is installed in different locations, the equipment becomes more complex and larger, and the mm also becomes larger. In addition, since one current transformer core can only be used for one purpose, multiple cores are required for relays, bar measurement, etc., which also causes larger size and is expensive in terms of loss. Put it away.

In view of these shortcomings, recently, measurement technology using optical fibers, which have excellent characteristics such as small diameter, insulation, non-induction, and environmental resistance, has been attracting attention, and optical magnetic field sensors that apply this are attracting attention. Attempts have been made to construct a current transformer.

An example of a cass-insulated three-phase current transformer using such an optical magnetic field sensor will be explained with reference to FIG.

The three-phase conductor 2 u-2W installed in the tank 1 has
An optical magnetic field sensor 8 is installed on the high electric field side, and a honeymoon CHI sensor 7 is installed outside the extended tank 1. The optical magnetic field sensor 98 is mainly composed of a Faraday element such as ZnSe, a polarizer, a -1//I wavelength plate, an analyzer, etc. It is connected to a detection device consisting of an element.

The action of this gas-insulated three-phase current transformer is as follows: In other words, when light is sent from the optical transmitter to the optical magnetic field unit 8 via the sealed terminal 7, this light After passing through the Faraday element, the random polarized light becomes linearly polarized light, which undergoes phase modulation with a quarter-wave plate and becomes circularly polarized light.Then, as it passes through the Faraday element, it becomes elliptically polarized light according to the size of the field. The intensity is modulated by the analyzer, returns to the sealed terminal 7, is sent to the detection device connected to this, is sent to the optical receiver, and is extracted as optical power, which is proportional to the magnitude of the magnetic field through arithmetic processing. Output is retrieved.

Since the optical magnetic field sensor 1J' has excellent insulation properties, it is possible to arrange Vjt near the conductors 2u to 2W as shown in [2], and the sealed terminal 7 can also be miniaturized. As a result, the gas-insulated three-phase current transformer is significantly reduced to 4IyfJi. Specifically, the length is about 20% and the diameter is about 60%.
There is an example of a scaled-down version in Hodokame. In addition, since the optical limit sensor 4 is free to use winter signals, it is possible to install only one sensor, unlike the conventional one, which has multiple cores for each purpose. This can be used for many purposes. Therefore, in this respect, it is possible to further downsize and simplify the current transformer, and it is also inexpensive in terms of lost costs.

[Problems with blue technology] By the way, in such a gas-insulated three-phase current transformer, t
The current in the conductor is calculated from the data in the first field. This calculation (formula based on Ampere's circuit law, which is the relation between the surrounding magnetic field and the center current)
It is carried out based on.

However, in a gas-insulated three-phase current transformer using such an optical magnetic field lens υ, since the three conductors are arranged close to each other, the influence of other phase magnetic fields increases, making it difficult to obtain sufficient accuracy. It is thought that it will not be possible.

This point will be explained below with reference to FIG. 3 and FIG. 4, which is described as a technique prior to the present invention.

That is, in Fig. 3, considering the current in the U-phase conductor 2u, the magnetic field line Φ in the figure crosses the V-phase and W-phase conductors 2■ and 2W, so in the vicinity of the conductors of the This U-phase conductor 2 is affected by the magnetic field generated by the current of the phase conductor itself.
The magnetic field due to the current of u is synthesized. This means ■ phase, W
The same is true when considering the currents of 2V and 2W in the phase conductors, and the magnetic field near each conductor has a complicated aspect. Therefore, when installing an optical magnetic field sensor near a conductor that measures the current and phase of the conductor, the accuracy of the 81 measurement data will be significantly reduced unless the influence of other phase magnetic fields is eliminated. Put it away.

However, in such a gas-insulated three-phase current transformer, it is not possible to eliminate the influence of such other-phase magnetic fields, and as shown in FIG. Since the configuration is such that they are connected by 9 and arranged in a circumferential manner, the magnetic field strength of all prefectural road valves is calculated by supplementing the gaps where there is no data with only one scattered data. That is, since the magnetic field strength of all prefectural road valves cannot be detected, the above-mentioned formula based on Ampere's circuit law does not hold, and there is a risk that a large error may occur when current is applied.

Therefore, it is thought that it is difficult to obtain a high-precision current transformer of the 1st to 3rd class, which is generally used for 4-meter measurements, among such gas-insulated three-phase current transformers.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to eliminate the influence of the magnetic fields of other phases on the optical magnetic field range of each phase by improving the configuration of the optical magnetic field range. 1
By making it possible to detect the magnetic field strength along the entire road,
The purpose is to establish a formula for the ampere circuit and provide a highly accurate gas-insulated three-phase current transformer.

[Summary of the Invention] The gas-insulated three-phase current transformer according to the present invention uses a magneto-optical element that controls the Faraday rotation angle by the strength of a magnetic field that exists only in the optical axis direction of the optical path (that is, only in the direction in which the light passes). This opto-magnetic field constitutes an opto-magnetic field sensor 11, and this opto-magnetic field is
J: What is the best way to create a continuous configuration in which each phase detects only its own magnetic field strength, eliminates the influence of the magnetic fields of other phases, and makes it possible to detect the magnetic field strength of a separate magnetic path? This is what I did. .

[Embodiments of the Invention] Examples of the gas-insulated three-phase current transformer according to the present invention as explained above will be specifically explained using FIGS. 5 and 6.
Note that the same parts as those in the prior art are designated by the same reference numerals, and the description thereof will be omitted.

What is shown in FIG. 5 is a first embodiment of a gas-insulated three-phase current transformer according to the present invention. A3 in Figure 5, conductors 2u to 2W
The surrounding area is made of flexible lead glass shaped like a thread! ζ' One continuous optical magnetic field Lnner 18 is at least 1
It is numbered around the circumference. This lead glass is a magneto-optical element that generates a Faraday rotation angle due to the strength of the magnetic field that exists only in the optical axis direction of the optical path. On the other hand, four terminals 7 are installed on the tank 1 in close proximity to the optical magnetic field sensors 18 of each phase, and an optical transmitter L E D is installed on the outside of the tank 1.
, a detection device 1 consisting of an optical receiver P D '
0 are provided and are sequentially connected by optical fibers 9.

The operation of this embodiment having the above configuration is as follows.

First, since the optical magnetic field is wrapped around the conductors 2LJ to 2■ and covers the entire roadside area, the magnetic field strength of all prefectural road valves can be detected. In particular, in this embodiment, the optical magnetic field range 18 is made of flexible lead glass in the form of a thread and is wound around the conductors 2U to 2■, so assembly work is easy and the current transformer is By combining the plurality of optical magnetic field sensors provided on the conductors of each phase of J3 and C into one, there is an advantage that the number of parts and the number of connection points with the microwave (optical)7 fibers can be reduced.

Furthermore, since the optical magnetic field thin film 18 is wrapped around the conductors 2u to 2v, the optical axis direction of the optical path coincides with the direction of conductor circumference, which is the magnetic field direction of each phase itself. Due to the characteristics, the optical magnetic field sensor 18 can detect only the magnetic field strength of each phase without the influence of the magnetic field strength of other phases.

Therefore, in the gas-insulated three-phase current transformer of this example, since the magnetic field strength for the entire magnetic path of each phase itself can be accurately detected, the formula 1 according to Ampere's circuit law holds true, and this configuration Since it is possible to perform circular integration by 1
High accuracy of class 3 to class 3 can be obtained.

Next, FIG. 6 shows the second part of the gas-insulated three-phase current transformer according to the present invention.
An example is shown.

In this embodiment, the optical magnetic field sensor 28 is made of the same lead glass as in the previous embodiment, but its cross-sectional shape is approximately square, and the conductor 2'Lj~2
(1) and is attached to the conductors 2u to 2'W (attachment number). Further, the optical fiber 9 is not provided between the optical magnetic field sensor 28 and the tank 1, and light is directly transmitted through space.

Since the configuration of this embodiment is the same for all three phases, only the U phase will be described below with reference to FIG. 7.

The optical magnetic field sensor 28, which has a substantially square cross section and is connected to the conductor 2u, has four planes 11a to 11d and a portion of the coat 1.
2. It is formed from a to 12d. Among the four corner parts 12a to 12d, three corner parts 12b to 12
(j has 4 planes for the two planes forming part of each corner.
A total reflection surface forming an angle of 5 degrees is formed. One plane 11 constituting the corner part 12a that does not become a total reflection surface
d is provided with a corner cube 13 for retro-reflection with two 45-degree reflective surfaces facing each other, and the other flat surface 11
A faces the tank 1 and forms a light entrance/exit surface 14 . Then, on the tank 1, a detection device 10 consisting of a direct optical transmitter LED, etc. is installed in place of the sealed terminal 7 at a position opposite to this entrance/exit surface 14, and the optical axis of the optical path and the aforementioned The light entrance/exit surface 14 of the magnetic field sensor is arranged perpendicular to the optical axis of the optical path.

In addition, in this embodiment, in J3, the polarizer and analyzer are installed on the optical transmitter LED and the detection device 10 side, respectively.

The operation of this embodiment based on the above configuration is as follows.

First, the linearly polarized light sent from the optical transmitter LED via the polarizer enters from the corner part 12a of the optical magnetic field sensor 1 28 perpendicularly to the light entrance/exit surface 14, and travels straight along the plane 11b. , is totally reflected in the right angle direction at the next corner portion 12b, and then travels straight along the t17 plane 11c. In the same way, a large sword is attached to the corner 128 along the plane 11a via 12G and 12d to a part of the corner.
It is retro-reflected by the corner cube 13 and travels through the corner section 12d, 12c, and 12b in the order of 12d, 12c, and 12b, and is spatially transmitted again from the plane 11a of the corner section 12a, and is transmitted to the detector M10. It reaches the optical receiver PD.

Therefore, in this embodiment as well, the optical magnetic field is covered by the sensor 28 around the conductor 2u, and the light circulates around the conductor, so that the orbital integral can be calculated as in the previous embodiment.

In particular, in this embodiment, the cross-sectional shape of the optical magnetic field sensor 28 is approximately square, thereby enabling spatial transmission, which has the advantage of increasing dielectric strength.

In this embodiment, birefringence due to total reflection at one point at each corner is compensated for by reciprocating the light, so there is no problem in terms of secondary accuracy.

As described above, in the present invention, the optical magnetic field sensor is circulated around the entire circumference of the conductor of each phase to enable circular integration, and the configuration is not limited to the illustrated embodiment. for example,
In the first embodiment, the number of turns of the optical magnetic field sensor 1 may be one or more, and the same effect can be obtained regardless of the number of turns. In addition, in the first embodiment, the detection device was installed outside the tank, and the detection device and the optical magnetic field fin 1 were connected using an optical fiber that penetrated the sealed terminal. The device may be attached and the two may be connected using optical fiber.

[Effects of the Invention] As explained above, according to the present invention, a magneto-optical element is adopted to be arranged around a conductor, and the magneto-optical element is arranged around the entire circumference of the conductor as one continuous structure. With a simple configuration, the influence of magnetic fields of other phases can be eliminated, and the magnetic field strength of the full magnetic path valve can be detected. We can provide precision gas-insulated three-phase current transformers.

[Brief explanation of the drawing]

Figures 1 to 4 are diagrams showing conventional gas-insulated three-phase current transformers, respectively, and Figures 1 (Δ) and (B) respectively show gas-insulated three-phase current transformers using current transformer cores. Figures 2A and 2B show a front view and side sectional view of a gas-free R3-phase current transformer using an optical magnetic field sensor. 1 is a sectional view showing the influence of a magnetic field, and FIG. 4 is a sectional view specifically showing a gas-insulated three-phase current transformer using an optical magnetic field sensor, which is a technology prior to the present invention. 5 to 7 are diagrams showing embodiments of the gas-insulated three-phase current transformer according to the present invention, and FIGS. 5 and 6 are sectional views showing the first and second embodiments, respectively; FIG. 7 is a partially enlarged sectional view of the second embodiment. 1.1a, 1b-...tank, 2 u ~ 2 W->5
body, 3... insulation spacer, 4... current transformer core, 5...
... Support plate, 6... Insulation shield, 7... Sealed terminal, 8, 18.28... Optical magnetic field sensor, 9... Optical fiber, 10... Detection device, 11 a to 11 d-
...Plane, 12a to 12d...Part of corner, 13...
・Corner cube, 14°15...Light entrance/exit surface, L
ED...optical transmitter, PD...optical receiver, OP...
Actor. Figure 1 (A) (B) Figure 2 (A) CB)

Claims (3)

[Claims] (1) Three-phase conductors are installed in a tank filled with 14 insulating gases such as SF6 gas, and around each conductor is an optical magnetic field sensor consisting of a magneto-optical element that generates a Faraday rotation angle depending on the strength of the magnetic field. A gas-insulated three-phase current transformer is provided, wherein the magneto-optical element reacts only to the magnetic field strength existing in the optical axis direction of the optical path, and the magneto-optical element is single and orbits around a conductor. The light passing through this magneto-optical element orbits around the guiding tree, and a detection device consisting of an optical transmitter, an optical receiver, etc. is installed on or outside the tank. A gas-insulated three-phase current transformer, characterized in that the light receiver of the detection device is configured to transmit the light that has been round-integrated at the optical magnetic field center. (2) The optical magnetic field sensor employs a flexible material such as lead glass as a magneto-optical element, is formed into a thread shape, and is wound around the magnetic field sensor, and is also used as a detection device. The gas-insulated three-phase current transformer according to claim 1, wherein optical transmission with the optical magnetic field sensor is performed by an optical fiber connected therebetween. (3) The optical magnetic field sensor has a substantially rectangular cross section, and has a shape including a light entrance/exit surface, a total reflection surface, and a retroreflection surface, and the detection device faces the optical magnetic field sensor on the tank. However, the detection device and the optical magnetic field sensor are arranged so that the light entrance/exit surfaces are perpendicular to the optical axis of the optical path, and the light transmission between the detection device and the optical magnetic field sensor is performed through the space between them. A gas-insulated three-phase current transformer according to claim 1.