JPS6325635Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a vacuum interrupter for power use.

(Prior art) In general, a vacuum interrupter has a pair of opposing electrodes that can be connected to and separated from each other in a vacuum container maintained at a high level of vacuum (10 ^-4 Torr to ^{10 -2} Torr). This is a switch used for disconnection. This vacuum interrupter houses opposing electrodes that have different potentials when separated, so the vacuum container is made of an insulator such as glass, and the end plate supporting the electrodes is metal, or the vacuum container has a high The electrode may be made of a resistive metal, and the end plate supporting the electrode may be made of an insulating material such as ceramic.

However, as shown in FIG. 1, in the case of a vacuum interrupter in which the vacuum vessel 1 is made of a high-resistance metal tube and the end plate 2 is a circular plate made of ceramic,
When a negative impulse voltage is applied to the center of the end plate 2 and a positive impulse voltage is applied to the periphery, the dielectric strength tends to decrease. This is because the equipotential surface is ceramic metallized 3
This is due to the fact that when the disk approaches near the end face of the disk, electric field concentration occurs, resulting in a difference in electric field strength between the center side and the peripheral side of the disk.

Therefore, in order to alleviate the electric field concentration near the ceramic metallized end face 3, an inner shield 4 is provided near the center on the inside of the end plate 2, and an outer shield 5 is provided around the periphery, as shown in an enlarged view in FIG. However, as the equipotential line 6 enters between the inner shield 4 and the ceramic end plate 2, the electric field concentration in the inner shield 4 becomes high, which has a large polarity effect on the impulse withstand voltage, causing instability. There are drawbacks to forming a state.

In the figure, 7 is an electrode, 8 is a lead rod that supports the electrode 7, 9 is an expandable bellows that airtightly connects the movable lead rod 8 and the end plate 2, and 10 is a connection between the vacuum container 1 and the end. An annular auxiliary member 11 is used to connect the lead rod 8 and the end plate 2 in an airtight manner. Further, 12 is an insulating cover that covers both end plates 2.

The electric field concentration between the inner shield 4 and the end plate 2 described above occurs not only on the fixed side of the lead rod 8 (section A in the figure) but also on the movable side (section B in the figure). The explanation thereof is the same as above, so it will be omitted.

(Purpose of the invention) In view of these circumstances, the present invention is designed to prevent the equipotential surface of a vacuum interrupter having a ceramic disc as an end plate from concentrating electric field on the ceramic metallized end face, and to prevent the electric field from concentrating on the ceramic metallized end face. The purpose is to eliminate the equipotential surface between the plates, alleviate the electric field concentration in the inner shield, and reduce the polarity effect of the impulse withstand voltage.

(Summary of the invention) Based on the above-mentioned purpose, the present invention provides a shield ring that faces the inner shield and electrically sandwiches the center of the ceramic, and provides a shield ring between the inner shield and the ceramic end plate. Prevents potential wires from entering,
This vacuum interrupter is equipped with a circular ceramic center electric field mitigation electrode that can prevent electric field concentration at the end of the inner shield.

(Example) Examples of the present invention will be described below with reference to FIGS. 3 to 5. In the drawings, the same reference numerals as in FIGS. 1 and 2 represent the same components, so redundant explanation will be omitted.

In FIG. 3, the disk ceramic central electric field relaxation electrode is constructed by carving a circumferential groove 8a in a lead rod 8 (FIG. 1) to which an electrode 7 is fixed at one end.
This shield ring 13 is embedded in the insulating cover 12 that covers the ceramic end plate 2 and the vacuum vessel 1. The shield ring 13 is shown in Fig. 4 A and C.
As shown in FIG. 4B, the ring is made of conductive metal, or as shown in FIG.

In FIG. 5, the disk ceramic central electric field relaxation electrode includes an inner protrusion 14 provided on a part of an auxiliary member 11, and a shield ring 13 made of a conductive metal, one end of which is fixed to the inner protrusion 14, attached to an insulating cover 12. Part of it will be buried. This shield ring 13 is
As shown in FIG. 4C, it is a circular plate whose peripheral edge is curved into a tubular shape, and is bent so that the cross section is L-shaped when attached.

In FIG. 6, the shield ring 13 is the same as that shown in FIG. 5, but the ceramic end plate 2 has a flat surface and is metalized near the center and around the periphery. It shows.

The shield ring 13 as described above functions to move the equipotential line 6 from the center side of the ceramic end plate 2 to the periphery side, as shown in FIG. 3, and relieves electric field concentration on the inner shield 4. Note that it is effective to make the diameter of this shield ring 13 equal to or slightly larger than the outer diameter of the inner shield 4.

(Effect of the invention) According to the invention described above, the inner shield 4
A shield ring 13 is disposed opposite to the ceramic end plate 2 so as to electrically sandwich the ceramic end plate 2 to prevent the equipotential line 6 from entering between the inner shield 4 and the ceramic end plate 2 and to prevent electric field concentration at the inner shield end. Since we have prevented
It is possible to obtain a vacuum interrupter that does not have a large polarity effect on impulse withstand voltage and can maintain a stable state.

[Brief explanation of the drawing]

Fig. 1 is a partially sectional front view showing a conventional vacuum interrupter, Fig. 2 is a partially enlarged sectional view of section A in Fig. 1, and Fig. 3 is a partially enlarged sectional view similar to Fig. 2 showing an embodiment of the present invention. 4A, B, and C are perspective views showing the shield ring, and FIGS. 5 and 6 are partially enlarged sectional views similar to FIG. 3 showing other embodiments of the present invention. 2... End plate, 4... Inner shield, 5... Outer shield, 6... Equipotential line, 13... Shield ring.

Claims (1)

[Scope of utility model registration request] In a vacuum interrupter in which both end plates are composed of ceramic discs, an inner shield is provided near the center of the ceramic disc, and an outer shield is provided near the periphery, the end plate 2 is opposite to the inner shield 4. A vacuum interrupter characterized in that a shield ring 13 is disposed to sandwich the vicinity of the inner shield, and a circular ceramic center electric field relaxation electrode is provided to prevent electric field concentration at the 4 ends of the inner shield.