JPS6020152A - Gas insulating bus provided with magnetic field detecting element - Google Patents

Abstract

PURPOSE:To make a titled bus inexpensive, and also to execute easily the maintenance and inspection by providing a magnetic field detecting element between a shunt electric conductor installed to the outside of a metallic sheath, and the metallic sheath so as to install the magnetic field detecting element at the outside of the metallic sheath. CONSTITUTION:A shunt electric conductor 12 provided to surround the whole circumference of a metallic sheath 3 has a U-shaped section, and toth its ends are welded to the outside circumferential surface of the metallic sheath 3. A magnetic field detecting element 8 is installed in a space 13 formed between this shunt electric conductor 12 and the metallic sheath 3, and its lead wire 9 passes through the shunt electric conductor 12 and is drawn out to the outside. In case of a current Ic flows to an electric conductor 2; a current Is corresponding to -Ic flows to the metallic sheath 3, but Is is shunted to Is1 and Is2 in the part where the shunt electric conductor 12 exists. As a result, a magnetic field proportional to the electric conductor current Ic is generated between the shunt electric conductor 12 and the metallic sheath 3, therefore, the electric conductor current Ic is detected by measuring a magnetic field of a point P by the magnetic field detecting element 8.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a magnetic field detection element for detecting conductor current.
This relates to gas insulated buses such as IL and GIS.

[Prior art]

As a means of measuring the conductor current of a gas-insulated bus bar, instead of the conventional method of using a CT (current transformer), a method of detecting the magnetic field created by the conductor current and determining the conductor current from the value is being considered. In this case, the magnetic field detection element is a light-applied confectionery that utilizes the fact that the refraction angle of light that passes through special glass (for example, lead glass) changes due to changes in the magnetic field.
It is considered promising because it is not affected by electrical noise.

FIG. 1 shows a conventional gas insulated bus bar equipped with such a magnetic field sensing element. A gas insulated bus bar 1 has a conductor 2 and a metal sheath 3
The space between them is insulated with a gas 4 such as SF6, and a magnetic field detection section 5 is provided in a part thereof. This magnetic field detection section 5 includes a flange 6 formed at the opening of the metal sheath 3.
, a blind lid 7 that seals the opening, a magnetic field detection element 8 supported by the blind lid 7, a penetrating member 10 that maintains the airtightness of the part where the lead wire 9 of this element passes through the blind lid 7, and an electrostatic charge to the element 8. It is composed of a shielding plate 11 and the like that shields the area.

In this case, the magnetic field detection element 8 needs to be installed inside the inner surface of the metal sheath 3. The reason is that the current ■c in conductor 2
This is because when the return current flows through the metal sheath 3, the return electric current s that returns to -IC flows, and the magnetic field is canceled outside the inner diameter of the metal sheath 3. That is, the magnetic field H at a point at a radial distance X from the center of the conductor 2 is less than the radius of the metal sheath 3.

Therefore, it can be detected, but beyond the above radius, 2πx
2πX and becomes undetectable.

As described above, it was conventionally believed that a magnetic field corresponding to a conductor current could only be detected inside the metal sheath, and therefore the magnetic field detection element had to be installed inside the metal sheath. For this reason, conventional gas-insulated busbars with magnetic field detection elements require pressure and vacuum resistance for the magnetic field detection element and lead wires, an airtight penetration member, and a bill-shielding plate inside. It has the disadvantage of being expensive due to the need to provide Furthermore, in the unlikely event that
If an abnormality occurs in the magnetic field detection element, it is necessary to open the blind cover to inspect it.
Another problem is that it requires extensive work to recover the gas and refill it after inspection, making inspection virtually impossible.

[Purpose of the invention]

In view of the above problems, an object of the present invention is to provide a gas insulated bus bar with a magnetic field detecting element that is inexpensive and easy to maintain and inspect by allowing the magnetic field detecting element to be installed outside the metal sheath. It is something.

[Structure of the invention]

For the above purpose, the present invention provides a shunt conductor that shunts the current flowing through the metal sheath (the above-mentioned return current) on the outside of the metal sheath. generate a magnetic field that
This magnetic field is detected by a magnetic field detection element.

〔Example〕

2 and 3 show an embodiment of the present invention.

In the figure, 12 is a shunt conductor provided so as to surround the entire circumference of the metal sheath 3. This shunt conductor 12 is the third
As shown in the figure, it has a U-shaped cross section, and both ends are welded to the outer peripheral surface of the metal sheath 3. In other words, the shunt conductor 1
2 electrically connects two points in the longitudinal direction of the metal sheath 3, so a part of the current flowing through the metal sheath 3 is divided there. This shunt conductor 12 is made of a highly conductive material, such as aluminum or aluminum. The magnetic field detection element 8 is installed in a space 13 formed between the shunt conductor 12 and the metal sheath 3, and its lead wire 9 passes through the shunt conductor 12 and is drawn out. When the magnetic field detection element 8 is an optical application element, the lead wire 9 is in the form of a bundle type optical fiber. Since the space 13 and the inside of the metal sheath 3 are completely isolated, the pressure remains at atmospheric pressure.
Therefore, as long as the penetration part of the wire 9 does not allow moisture to enter, +f is good, and conventionally, no airtightness is required (1
゜With the above configuration, when a current IC (force) flows through the conductor 2, a current Is corresponding to 1 CK flows through the metal sheath 3, but in a certain part of the shunt conductor 12, i and IS become 1s1 (
metal sheath side) and l52 (shunt conductor side). Therefore, the magnetic field Hp at the position P of the magnetic field detection element 8 is as follows: 2πX = □ -IS2 2πX = -1-1r<·cm. ... Old 1 Old ... (3) 2π
It becomes X. However, K is a constant (0<K<1) determined by how many parts of the force s flow as the force s2, and is uniquely determined from the structure of the magnetic field detection section 5. In other words, equation (3) shows that when the structure of the shunt conductor 12 is determined, K is determined, and the magnetic field Hp at point P becomes proportional to the conductor current IC. In other words, since the shunt conductor 12 is provided, a magnetic field proportional to the conductor current ICK is generated between it and the metal sheath 3.

Therefore, by measuring the magnetic field at point P using the magnetic field detection element 8, the conductor current IC can be determined from equation (3).

Note that the value of K depends on the conductivity and plate thickness of the shunt conductor 12. In order to increase K, the shunt conductor 12 may be made of a thick material with high conductivity.

Fifth, according to this embodiment, a magnetic field corresponding to a conductor current can be detected with the magnetic field detection element installed outside the metal sheath.

FIG. 4 shows another embodiment of the invention. In this embodiment, a shunt conductor 12 is provided around a part of the metal sheath 3. FIG. 5 shows still another embodiment of the present invention, in which two shunt conductors 12A are provided around a part of the metal sheath 3.
, 12B are provided. Although not shown, in either case, the magnetic field detection element is the shunt conductor 12 or 12A, 12B.
and the metal sheath 3. In the structure shown in the fourth factor or in FIG. 5, the above-mentioned value of K becomes small, but when the detection sensitivity of the magnetic field detection element is high, such a structure can lower the cost.

〔Effect of the invention〕

As explained above, according to the present invention, by providing the shunt conductor outside the metal sheath, it is possible to detect the magnetic field according to the conductor current with the magnetic field detection element installed outside the metal sheath. Highly airtight processing of the magnetic field detection part is no longer required, which simplifies the structure and reduces the cost.In addition, inspection and replacement of the magnetic field detection element can be performed without affecting the inside of the gas-insulated bus bar. There are big advantages.

[Brief explanation of drawings]

Fig. 1 is a cutaway front view of essential parts of a conventional gas insulated bus bar with a magnetic field detection element, Fig. 2 is a perspective view of a gas insulated bus bar with a magnetic field detection element according to two embodiments of the present invention, and Fig. 3 is a front view of the gas insulated bus bar with a magnetic field detection element. The enlarged sectional view of the main part, and FIGS. 4 and 5 are perspective views showing other embodiments of the present invention, respectively. 1...Gas insulated bus bar, 2...Conductor, 3
...Metal sheath, 4...Gas, 5...
...Magnetic field detection section, 8...Magnetic field detection element, 1
2, 12A, 12B... Branch conductor. Figure 2 Figure 3 Figure 4 Figure ζ Figure 5

Claims (1)

[Scope of Claims] (υ In a gas insulated bus bar in which a conductor and a metal sheath are insulated with gas, a magnetic field detection element for detecting a magnetic field corresponding to a conductor current is attached, wherein the metal A gas insulated bus with a magnetic field detection element, characterized in that a shunt conductor is attached to shunt the current flowing through the sheath, and the magnetic field detection element is installed between the shunt conductor and the metal sheath. The gas insulated bus bar with a magnetic field detection element according to item 1, wherein the shunt conductor is provided so as to surround the metal sheath, and both ends of the metal sheath in the longitudinal direction are electrically connected to the metal sheath. (3) Permissible % The gas insulated busbar with a magnetic field detection element according to claim 1, wherein the shunt conductor is provided in a part of the periphery of the metal sheath, and Both ends of the direction are electrically connected to the metal sheath.