Abstract: To simply and accurately determine the position of an edge, the depth or the height of a flaw including a surface crack, a corroded portion near the surface layer of a thick specimen, and a minute damage.

Abstract: [Object] To simply and accurately determine the position of an edge, the depth or the height of a flaw including a surface crack, a corroded portion near the surface layer of a thick specimen, and a minute damage.

Abstract: A gas-filled circuit breaker includes a hermetically sealed tank formed by a surrounding wall filled with an insulating gas, at least one pair of contacts which are arranged in the inside of the surrounding wall, and a contact operating device for connecting the contacts to each other for conducting electricity therebetween and separating the contacts from each other for interrupting the electricity therebetween. The contact operating device includes a force generating device for generating a force for operating the contacts, and the contact operating device is arranged outside of the surrounding wall. A rotational shaft device is connected to the force generating device outside of the surrounding wall and extends from the outside of the surrounding wall to the inside thereof so that the force generated by the force generating device is transmitted through the surrounding wall to the inside thereof.

Abstract: An operating device for a gas circuit breaker includes an operating piston reciprocably movable between a first position and a second position, with the operating piston dividing an internal space of the operating cylinder into a first chamber and a second chamber. An exhaust port in the operating cylinder communicates with the first chamber when the operating piston is disposed near the second position, and the exhaust port communicates with the second chamber when the operating piston is remote from the second position. High-pressure air is introduced into the first chamber at the time of the breaking operation. An exhaust valve device discharges the air from the first chamber when the air pressure within the first chamber decreases below a predetermined level. The exhaust valve device includes a valve element having a pressure-receiving portion receiving the air pressure from the first chamber.