Vacuum switchgear

Abstract

A main circuit switching unit and an isolator are accommodated in a vacuum container. A first conductor and a main circuit conductor are arranged to extend in and out of the vacuum container. A movable electrode of the main circuit switching unit is connected to the first conductor through a first flexible conductor, and a movable electrode of the isolator is connected to the main circuit conductor through a second flexible conductor. A shield is arranged around the first conductor and the main circuit conductor. Another shield is arranged around a connecting portion between the first flexible conductor and the movable electrode of the main circuit switching unit. A still another shield is arranged around the isolator. A further another shield is arranged around the second flexible conductor. These shields are secured to the vacuum container through insulating spacers. This arrangement instantly eliminates a dielectric breakdown phenomenon that occurs at electric field concentrated regions by the shields to prevent a dielectric breakdown caused by particulate foreign matters and thereby improve an insulation reliability of the devices.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a vacuum switchgear and more particularly to a vacuum switchgear, in which a switch having a stationary electrode and a movable electrode is enclosed in a vacuum container that requires grounding. [0002] As a conventional vacuum switchgear, for example, there is a construction, in which a vacuum container accommodates a main circuit switching unit for connecting and disconnecting a main circuit conductor to and from a load side conductor or a bus side conductor and a main circuit / earth selecting unit for connecting the main circuit conductor to and from the bus side conductor or the load side conductor and an earthing conductor and in which the vacuum container is formed of a grounded metal or an insulating material with a grounded layer on its surface. This vacuum container accommodates the main circuit conductor and a part of each of the bus side conductor, the earthing conductor and the load side conductor. Furth...

AI Technical Summary

Benefits of technology

[0005] An object of this invention is to prevent a dielectric breakdown due to foreign particulates and improve the insulation reliability of devices.

[0007] In this construction, for instance, when particulate foreign matters reach a high electric field area near the conductors, a dielectric breakdown phenomenon occurs only between the conductors and the shield but not between the shield and the vacuum container. Thus, this dielectric breakdown does not result in a ground fault, nor does it lead to a power system failure. More specifically, in the event that a dielectric breakdown phenomenon is caused by particulate foreign matters, the shield and the conductors are instantly brought to the same potential. However, since the shield is insulated from the vacuum container, an electric field between the conductors and the shield disappears, no longer accelerating charged particles generated by the dielectric breakdown. The dielectric breakdown therefore can no longer persist, and the dielectric strength can recover instantly, preventing damages to the devices. This in turn can prevent a ground fault and also prevent the dielectric breakdown phenomenon from providing a cause for a possible power system failure.

[0008] According to the invention it is possible to prevent damages to the devices and a ground fault and to prevent a cause for a possible power system failure.

Problems solved by technology

However, since the shield is insulated from the vacuum container, an electric field between the conductors and the shield disappears, no longer accelerating charged particles generated by the dielectric breakdown.

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