Kabushiki Kaisha Toshiba

Kiyoshi Kagenaga

Kenji Watanabe

Junichi Sato

Eiji Kaneko

Mitsutaka Honma

Hiromichi Somei

Kumi Uchiyama

The flux density Bct is applied at the center area of the electrode. The flux density Bct is adjusted within the range A of 0.75 to 0.9 times greater than the axial flux density Bcr which gives the lowest arc voltage between the electrodes against each breaking current. The axial flux density monotonously increases from the center to the circumferential area of the electrode. Here, the radial position where the axial flux density Bcr which gives the lowest arc voltage Vmin is adjusted within the region B of 20% to 40% of the radius of the electrode. The axial flux density is made monotonously increase in an outer area from the region B and give the maximum value Bp in a circumferential area equal to or beyond 70% of the radius of the electrode. The maximum value Bp is adjusted within the range C of 1.4 to 2.4 times greater than the flux density Bct given at the electrode center.

Vacuum valve

A method for improving flux density in a vacuum valve, includes producing, with a vacuum valve, an axial magnetic field parallel to an arc generated between a movable and a stationary electrodes facing each other, and adjusting a magnitude of an axial flux density between the electrodes to increase gradually from a center area of the electrodes toward a circumferential area of each electrode. A point gives a maximum value (Bp) of the axial flux density at a location of and beyond 70% of a radius from the center of each electrode, and the maximum value (Bp) of the axial flux density in a radial line from the center to a circumferential end to be 1.4 to 2.4 times greater than a flux density of the center Bct of each electrode.

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Tokoy, Japan

Kiyoshi Kagenaga