Abstract: An AC-DC electric power converting station is provided wherein circuit lines consisting of converter transformers/ positive and negative polarity valve structures/ DC reactors/ DC circuit breakers are of L-shape and inverted L-shape. The positive and negative polarity valve structures are so arranged that their surfaces in the longitudinal direction face each other. The converting transformers are arranged along the other surfaces of the positive and negative polarity valve structures in the longitudinal direction thereof. The DC reactors and DC circuit breakers are series-connected in the vicinities of the outputs in the direction of width of the positive and negative polarity valve structures. AC and DC switchgears of gas insulated type are arranged to face each other so that they sandwich the positive and negative polarity valve structures therebetween. Conduit air cables connect the positive and negative polarity valve structures and the AC and DC switchgears.

Abstract: In a method for detecting foreign matters present in gas sealed electrical apparatus including a tank at the ground potential and containing an insulating gas and a high voltage live part disposed in the tank, a voltage is applied to the high voltage live part causing generation of ultrasonic waves and the ultrasonic waves propagated through the tank is sensed by a sensing element mounted on the tank.

Abstract: In a protective gap device for protecting a circuit breaker, there are provided a cylindrical metalic shell, a high voltage electrode unit, and a low voltage electrode unit. The high and low voltage electrode units are respectively provided with a main electrode, a trigger electrode, and a cylindrical electrode plate, each of the trigger electrodes having a rod-shaped electrode so as to form a trigger gap between the main electrode and the trigger electrode.

Abstract: A protecting apparatus for a series capacitor in an AC power circuit includes an enclosure filled with a low pressure insulating gas. A discharge gap device, a bypass switch for the series capacitor and an electromagnetic repulsion device for closing the bypass switch in response to the discharge of the series capacitor are assembled in the enclosure in alignment with each other. A metallic cylinder is provided around the assembly forming a return path for the capacitor discharge current to cooperate with the gap device and its support. In this way, the impedance of the capacitor discharge passage can be effectively reduced to permit rapid removal of excess terminal voltage from the series capacitor.