JPS60100767A - Current measuring device of gas insulation opening and closing device - Google Patents

Abstract

PURPOSE:To measure precisely a current with a small-sized, lightweight device by detecting a current flowing through a bus conductor by a magnetooptic element provided at the lower part of a container which has small thermal influence. CONSTITUTION:The bus conductor 11 is arranged in the bus container 10 to constitute a bus 12. An electric shield 14 is provided near the lower internal surface of the bus container 10 across a support 13, and the bus container 10 and electric shield 14 are held at the same potential. Plural magnetooptic elements 16 are arranged in the space part A between the electric shield 14 and support 13. This magnetooptic element 16 is connected to a measuring device through an optical fiber cable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a current measuring device in a gas-insulated switchgear using a magneto-optical element.

[Technical background of the invention and its problems]

In recent years, with the increase in demand for electricity, the demand for electricity has increased. , voltage and transmission current are constantly increasing. However, under these current circumstances, the influence of electromagnetic interference on cables that connect relay rooms and current transformers in substations, switchyards, etc. provided on power transmission routes is increasing. Current transformers are used to measure current, and conventional current transformers employ a wire-wound type.

The structure of this conventional wire-wound current transformer will be explained with reference to FIG. A bus conductor 2 is supported via an insulating spacer 3 concentrically with a cylindrical container 1 filled with an insulating gas. A mounting plate 5 for fixing the current transformer support 4 is provided between the insulating spacer 3 and the container l. Further, a cylindrical container 6 is connected to the container 1 via an insulating spacer 3 and a mounting plate 5, and a bus conductor (not shown) is provided inside the container 6. electrically connected to. The current transformer support 4 has a cylindrical shape, and one end surface is fixed to a mounting plate 5 so as to be arranged concentrically with the container 1. A current transformer 7 is installed on the outer periphery of the current transformer support 4.
is attached and tightened with stud 8. Further, a shield 9 for mitigating electric field concentration is attached to the end of the current transformer support 4. The current transformer 7 uses a cylindrical coil (two-turn coil).

In the above configuration, when a current flows through the bus conductor 2, a magnetic field is generated around the axis of the bus conductor 2. A current flows through the current transformer 7 placed under this magnetic field due to electromagnetic induction.
This current is passed through a cable connected to the current transformer 7 to an external measuring device and the current is measured.

By the way, conventional wire-wound current transformers have good measurement accuracy because they can integrate the magnetic path occupied by the bus conductor current over the entire circumference, but on the other hand, it takes a lot of time and effort to assemble the windings. The disadvantages are that the manufacturing cost of the winding wire is high, and the winding wire is large and heavy. Furthermore, the cable connecting the current transformer 7 and the measuring device is susceptible to the influence of magnetic fields, making it difficult to perform precise measurements in strong electric fields.

[Purpose of the invention]

It is an object of the present invention to eliminate the above-mentioned drawbacks and provide a current measuring device for a gas-insulated switchgear that is small, lightweight, and highly reliable.

In order to achieve the above object, in the present invention, a magneto-optical element is arranged in a magnetic field generated depending on the magnitude of a current, an optical shear fiber cable is connected to this magneto-optical element,
The current is measured using the polarization phenomenon caused by the magnetic field of the magneto-optical element.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIGS. 2 and 3. A cylindrical busbar conductor 11 is arranged in a cylindrical busbar container 10 which is filled with an insulating gas such as SF and arranged almost horizontally, and is insulated and supported concentrically with the busbar container by an insulating spacer (not shown). A bus bar 12 is configured.

An electric shield 14 is provided near the inner surface of the lower part of the busbar container 10 in the figure with a support 13 interposed therebetween. The support 13 is made of metal so that the potential of the busbar container 10 and the potential of the electric shield 14 are the same. As a result, a space is formed between the electric shield 14 and the inner surface of the busbar container.

The electric shield 14 has a plate-like configuration having a plurality of holes J5, and is arranged concentrically with the busbar container 10. In addition, the axial end of the bus bar 12 of the electric shield 14 and the bus bar container 100
The circumferential end portion is rounded and bent so that its tip is close to the busbar container 10. Hole 1 of electrical shield 14
5 is provided parallel to the axis of the generatrix 12 in a portion other than the end portion. Further, a plurality of magneto-optical elements 16 are arranged in the space A between the electric shield 14 and the support 13. This magneto-optical element 16 is connected to a measuring device via an optical fiber cable (not shown). By the way, when the busbar 12 is placed horizontally, the upper part of the busbar container 10 is heated by Joule heat due to the current flowing through the wire conductor 11.
Insulating gas temperature increases. Further, even when the gas insulated switchgear is placed outdoors, the humidity of the insulating gas in the upper lounge in the busbar container 10 increases due to direct sunlight. On the other hand, the magneto-optical element 16 is easily affected by temperature, and is 0°C to 80°C.
A measurement error of ±1 to 2 inches occurs due to temperature changes.

Therefore, in consideration of the influence of temperature on the magneto-optical element 16, it is preferable that the magneto-optical element 16 be placed within approximately 45 degrees (==) below the perpendicular line of the generatrix 12 axis cross section.

Next, the operation in configuration 1'= of this embodiment will be explained.

Due to Joule heat generation due to the current flowing through the bus conductor 11, the temperature of the insulating gas near the bus conductor 11 rises, and the high temperature insulating gas stagnates in the upper space of the bus container 10 due to convection. However, the change in the insulating gas temperature in the lower space of the busbar container 10 is smaller than that in the upper part. Furthermore, when the bus bar container 10 is exposed to direct sunlight, the temperature of the insulating gas in the upper space of the bus bar container 10 similarly increases, but the temperature increase of the insulating gas in the lower space is extremely small.

On the other hand, if there are minute metal foreign objects in the bus bar container 10,
This metallic foreign material is collected on the electrical shield 14 having a relatively high potential gradient while repeating the behavior of the flying spring, and once it enters between the electrical shield 14 and the busbar container 10, it stops its behavior.

In this embodiment, the magneto-optical element 16 is connected to the busbar container 10.
Since the magneto-optical element 16 is disposed in the lower space of the magneto-optical element 16, it is less susceptible to the temperature rise of the generatrix, so that even the magneto-optical element 6, which has temperature dependence, can be measured with high precision. Further, since the magneto-optical element 16 is covered with the electric shield 14 having the hole l5, electric field concentration on the magneto-optical element 16 and the optical fiber cable is alleviated. Furthermore, it is possible to prevent an accident of dielectric breakdown of the bus bar 12 due to flying metal foreign matter.

〔Effect of the invention〕

As explained above, according to the present invention, the magnitude of the current flowing in the bus conductor is detected using a magneto-optical element provided at the bottom of the container where there is little thermal influence, and the magneto-optical element is surrounded by an electric shield. Since it is arranged in such a way that it is small and lightweight, it is possible to perform accurate current measurement.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a current transformer of a conventional gas-insulated switchgear, Fig. 2 is a cross-sectional view showing an embodiment of a current measuring device according to the present invention, and Fig. 3 is a view taken from the nt-m arrow in Fig. 2. It is a sectional view seen from the direction. 10... Bus bar container, 11... Bus bar conductor, 12... Bus bar, 14... Electrical shield, 15... Hole, 1G...
Magneto-optical element.

Claims (1)

[Claims] A busbar consisting of a busbar container filled with an insulating gas and arranged horizontally, a busbar conductor provided concentrically with the busbar container inside the busbar container, and a magneto-optical element arranged near the inner wall of the busbar container. and an electric shield having a hole arranged so as to surround the magneto-optical element, and the magneto-optical element is arranged near the inner wall of the busbar container where the thermal influence of the busbar is small. Current measuring device for gas insulated switchgear