Abstract: A vacuum valve according to embodiments of the present disclosure comprise a prescribed shaped vacuum insulation vessel 1 having openings on its both ends, sealing metal fittings 2,3 configured to seal the openings of the vacuum insulation vessel 1 respectively, and a pair of contact points 5,6 which can be brought into contact or out of contact with each other and is arranged within the vacuum insulation vessel 1, wherein the vacuum insulation vessel 1 includes a base material layer 1c of aluminum oxide, a 1st oxidization promotion layer 1a whose oxygen combination was promoted, which 1st oxidization promotion layer 1a is formed on the inner circumference of the base material layer 1c, and a 2nd oxidization promotion layer 1b whose oxygen combination was promoted, which 2nd oxidization promotion layer 1b is formed on the outer circumference of the base material layer 1c.

Abstract: A vacuum valve according to embodiments of the present disclosure comprise a prescribed shaped vacuum insulation vessel 1 having openings on its both ends, sealing metal fittings 2,3 configured to seal the openings of the vacuum insulation vessel 1 respectively, and a pair of contact points 5,6 which can be brought into contact or out of contact with each other and is arranged within the vacuum insulation vessel 1, wherein the vacuum insulation vessel 1 includes a base material layer 1c of aluminum oxide, a 1st oxidization promotion layer la whose oxygen combination was promoted, which 1st oxidization promotion layer 1a is formed on the inner circumference of the base material layer 1c, and a 2nd oxidization promotion layer 1b whose oxygen combination was promoted, which 2nd oxidization promotion layer 1b is formed on the outer circumference of the base material layer 1c.

Abstract: A direct-current interrupter in an embodiment includes a current-carrying path and a current-interrupting path connected in parallel to the current-carrying path. The current-carrying path includes a first switch and a second switch connected in series and a resistor connected in parallel to the second switch. The first switch has a predetermined first withstand voltage property and switches between conduction and non-conduction of current by using no semiconductor switch. The second switch has a second withstand voltage property lower in withstand voltage property than the first withstand voltage property and switches between conduction and non-conduction of current by using no semiconductor switch. The resistor protects the second switch from voltage to be applied to the second switch. The current-interrupting path includes a semiconductor switch and a current source connected in series and a non-linear resistor connected in parallel to a series connection of the semiconductor switch and the current source.

Abstract: According to one embodiment, a tank-type vacuum circuit breaker includes a tank, a vacuum valve provided in the tank, an insulating layer provided on an outer circumference of the vacuum valve, having a fixed side interface connecting portion and a movable side interface connecting portion, a grounding layer provided on an outer circumference of the insulating layer, a fixed side bushing having an interface connecting portion connected to the fixed side interface connecting portion, a fixed side porcelain tube to house the fixed side bushing, a movable side bushing having an interface connecting portion connected to the movable side interface connecting portion, a movable side porcelain tube to house the movable side bushing, and insulation gas filled in the tank, at an approximately atmospheric pressure.