JPH0450663A - Current measuring device - Google Patents

Abstract

PURPOSE:To make it possible to measure the current in its own phase accurately by constituting a plane including a magnetooptic element in each phase and the central axis of a conductor so that the plane intersects approximately orthogonally with a plane wherein the central axes of three conductors in three phases are arranged. CONSTITUTION:When a current flows through a conductor 1, a magnetic field is correspondingly generated in an iron core 16. The plane of polarization of the incident light that is cast into a magnetooptic element 8 through an optical fiber 9A is rotated by the Faraday effect in correspondence with the magnetic field in a gap 17. The transmitted light is received, nd the signal is processed. As a result, the current flowing through the conductor 1 can be measured. When the effect of the amgnetic field generated by the current flowing through the conductor 1 in an other phase, the magnetic field generated by the current in the other phase is generated in the direction which is approximately orthogonal to the tangent line on the circle of the shape of the iron core 16 having the gap at the provided position of the magnetooptic element 8. Therefore the magnetic-field detecting sensitivity is low. On the other hand, the magnetic field by the current in its own phase is generated in the tangent-line direction of the circle. Therefore, the magnetic-field detecting sensitivity is high, and the current in its own phase can be accurately measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a current measuring device that measures a current flowing through a conductor.

[Conventional technology]

FIG. 4 is a perspective view of a conventional current measuring device disclosed in, for example, Japanese Utility Model Application No. 149979/1985, with a part cut away. In the figure, (1) is a cylindrical conductor that conducts current, and C) is a current transformer installed surrounding conductor (1). Although the details are not shown, it is connected to a link-shaped iron core and wound around this iron core. The conductor (1) is electrically connected to the conductor (1) and has the same potential as the conductor (1). (3) is a current-light converter provided in the hollow part (4) of the conductor (1);
Fig. 5 is a plan view showing the details, and Fig. 6 is M- of Fig. 5.
It is a sectional view along the M line.

(5) is a tripod core, and a gap (6) is formed in the center leg. (7) is the winding wound above and below the center leg of the tripod core (5), and 8 is the gap (6) in the center leg of the tripod core (5).
It is a magneto-optical element installed in the optical system, and is composed of an element having a Faraday effect such as a button glass, a polarizer, an analyzer (both not shown), and the like. <9A) and (9B) are optical fibers whose one end is optically coupled to the magneto-optical element (8), and whose other end is connected to the through hole (10) formed in the center leg of the tripod core (5). ).

Returning to FIG. 4, (11) is a lead wire connecting the winding of the current transformer (2) and the winding (7) of the current-optical converter (3);
12) is a shield provided to cover the current transformer (2) and the lead wire (11) to alleviate the electric field, and like the current transformer (2), it is electrically connected to the conductor (1) and is the same as the current transformer (2). It is at electric potential. The above items (1) to (12) are housed in a cylindrical metal container (not shown), and this metal container is filled with sulfur hexafluoride (SF6) gas as an insulating medium.

Furthermore, the optical fibers <9A) and (9B) are led out of the metal container.

Next, the operation will be explained. When a current flows in the conductor (1), a current proportional to this current flows in the winding of the current transformer (2) and therefore in the current-to-light converter ( 3) winding (similarly flows to the sword).

This generates a magnetic field in the air gap (6) in which the magneto-optical element (8) is placed. On the other hand, light emitted from a light emitting source (not shown) is transmitted to the magneto-optical element ts via an optical fiber (9A).
incident on +. Due to the Faraday effect of light whose plane of polarization is made constant by a polarizer, the plane of polarization rotates depending on the strength of the magnetic field. Transmitted light corresponding to the rotation angle is extracted by the detector, and this transmitted light is received by a light receiver (not shown) through the fiber (9B), thereby detecting the gap (
6) We can know the strength of the magnetic field in the conductor (
1) Measurement of the current flowing through can be performed.

[Invention or problem to be solved]

Since the conventional current measuring device is configured as described above, in the event of a failure or maintenance/inspection, the insulating medium in the metal container is collected into another container, and the conductor contained in the metal container is Furthermore, it is necessary to disassemble the current measuring device installed in the hollow part, making it difficult to perform maintenance/inspection or to quickly restore the device in the event of a failure.

In the case of a three-phase phase-separated bus, there is a method of installing an electromagnetic induction current transformer using a traditional ring-shaped iron core and windings so as to surround it outside the metal container, but in this case, Compared to the magneto-optical type, there are problems such as the iron core is large when high precision and high loads are required, and it is easily affected by the electromagnetic field at the installation location.

This invention was made in order to solve the above-mentioned problems, and provides a current measuring device that is magneto-optical and can quickly perform maintenance/inspection, troubleshooting, and recovery. The purpose is to obtain.

[Means to solve the problem]

The current measuring device according to the present invention measures the current in the conductor of a three-phase phase separation bus bar, and is composed of an iron core with a gap surrounding a metal container and a magneto-optical element provided in the gap. The optical element and the central axis of the conductor are arranged so that the plane containing them is orthogonal to the plane in which the central axes of the three three-phase conductors are arranged.

[Effect]

In the current measuring device of the present invention, a magnetic field is generated in the gap in accordance with the current flowing through the conductor in each phase, and this magnetic field is detected by a magneto-optical element, and is located at a position where the influence of the magnetic field due to the current in the conductor of the other phase is small. Since magneto-optical elements are arranged, the current in each phase can be measured with high accuracy.

Furthermore, since the current measuring device is placed outside the metal container, it is possible to
Able to perform maintenance/inspection and troubleshooting.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
FIG. 2 is a perspective view showing a current measuring device according to an embodiment of the present invention, and a sectional view taken along a plane perpendicular to the central axis of the conductor (1), both of which show only the -phase component. (
1) is a cylindrical conductor for conducting electricity, and (15) is a conductor (
It is a cylindrical metal container that stores 1), and SF and gas are sealed inside as an insulating medium. (16) is an iron core with a gap provided surrounding the metal container (2), (17
) is the gap, and 6 is a magneto-optical element provided in the gap (17), which, like the conventional example, is composed of an element having a Faraday effect such as lead glass, a polarizer, an analyzer, etc.

(9A) and (9B> are optical fibers each having one end optically coupled to the magneto-optical element B). Due to the magnetic field component in the tangential direction of the circle of the gapped core (16),
The plane of polarization of the light incident from the optical fiber (9A) is rotated.

FIG. 3 is a sectional view showing the arrangement of three phases of the current measuring device shown in FIGS. 1 and 2, and as in the case of FIG. 2,
A cross section taken along a plane perpendicular to the central axis of the conductor (1) is shown. The conductor (1) corresponds to one phase, and a three-phase phase-separated bus bar is constructed by housing each of the conductors (1) in three grounded metal containers (15). The three conductors (1) are arranged so that their central axes are on the same horizontal plane. In each phase, the planes containing the central axes of the magneto-optical element 8) and the conductor (1) are arranged perpendicular to the horizontal plane.In other words, the magneto-optical element 6 is arranged vertically above the conductor (1). In order to prevent the three-phase metal containers (15) from being electrically connected in places other than shown to form a closed circuit, insulating materials (not shown) should be placed between them where necessary. This is to prevent if a closed circuit were to be formed, a current in the opposite direction to the current in the conductor (1) would flow into the metal container (15).

Next, the operation will be explained. When a current flows through the conductor (1), a magnetic field is generated in the gapped iron core (16) in response, and in the same way as in the past, light incident on the magneto-optical element 8 via the optical fiber (9A) is caused to flow through the gap (17). ) The plane of polarization rotates due to the Faraday effect according to the magnetic field in the conductor (1), and by receiving the transmitted light and processing the signal, the conductor (1)
The current flowing through can be measured.

Furthermore, considering the influence of the magnetic field due to the current flowing through the conductor (1) of the other phase, at the installation position of the magneto-optical element 8, the magnetic field due to the other phase current is approximately equal to the tangent of the circle of the gapped core (16). Magnetic field detection sensitivity is low because it occurs in orthogonal directions. On the other hand, since the magnetic field due to the own-phase current is generated in the tangential direction of the circle, the magnetic field detection sensitivity is high, and therefore the own-phase current can be accurately measured with almost no influence from other-phase currents.

In the above embodiment, the magneto-optical element 8 is made of lead glass, but other Faraday elements may be used. In addition, although the magneto-optical elements (8) for each phase were installed above the conductor (1), they may also be installed vertically below. In this case, solar radiation outdoors is blocked and the magneto-optical elements (8) are prevented from being affected by temperature rise. This has the effect of reducing the impact. Further, although the three-phase conductors are shown arranged horizontally, they may also be arranged vertically.

In addition, although a phase-separated busbar for SF6 gas is shown, it may also use air or insulating oil as the insulating medium, and other busbars such as conduit aerial transmission lines, bushings, cable heads, disconnectors, circuit breakers, etc. It can also be applied to locations where three phases are separated in some areas.

〔Effect of the invention〕

As described above, according to the present invention, the plane is composed of an iron core with a gap surrounding a metal container and a magneto-optical element provided in the gap, and includes the magneto-optical element of each phase and the central axis of the conductor. Since the central axes of the three conductors of the three phases are configured to be perpendicular to the plane in which they are arranged, magneto-optical current measurement is performed, and it is easy to handle during maintenance, inspection, and troubleshooting. In addition to being able to perform recovery quickly,
This has the effect of reducing the influence of currents in other phases and allowing accurate measurement of the current in the own phase.

[Brief explanation of drawings]

1 and 2 are a perspective view and a sectional view showing a current measuring device according to an embodiment of the present invention, and FIG. 3 is a sectional view showing the arrangement of three phases of the current measuring device shown in FIGS. 1 and 2. Figure 4 is a perspective view showing a conventional current measuring device, Section 5 is a plan view showing the current-light converter of the current measuring device shown in Fig. 4, Section 6 is a line ■-■ in Fig. 5. FIG. In the figure, (1) is a conductor, (8) is a magneto-optical element, (
15) is a metal container, (16) is an iron core with a gap, <17
) is a gap. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Masuo Oiwa, Patent Attorney Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] The above conductor of a three-phase phase-separated bus bar consists of three conductors whose central axes are arranged on the same plane, three metal containers that house each of these conductors, and an insulating medium sealed in these metal containers. A device for measuring flowing current consists of an iron core with a gap provided surrounding the metal container of each phase and a magneto-optical element provided in the gap of the iron core with a gap, and the magneto-optic element of each phase and 1. A current measuring device characterized in that a plane including the central axes of the conductors is arranged so as to be substantially orthogonal to a plane in which the central axes of the three conductors are arranged.