Abstract: A power conversion system always keeps a constant voltage level relative to the ground potential and shows an improved controllability for the noise compensation current. In the noise reduction circuit of the system, a rectified DC voltage is applied to the positive side output line and the negative side output line. The DC voltage is divided by a pair of capacitors connected in series with the intermediary point held to the ground potential. Thus, the positive side output line can always supply a positive voltage that is held to a constant level relative to the ground potential. Similarly, the negative side output line can always supply a negative voltage that is held to a constant level relative to the ground potential. Additionally, as the transistors are controlled for on/off operations by the amplifier, the noise compensation current flows through the noise reduction circuit between the input grounding terminal of the full-wave rectifier and the ground.

Abstract: A high voltage thyristor valve of the air insulation type erected upright on a valve hall is disclosed, which comprises a thyristor valve body erected in the valve hall and a plurality of reinforcing means stretched between the thyristor valve body and inner walls of the valve hall, each of the reinforcing means including a wire rope and an insulator.

Abstract: A high voltage apparatus having the three-dimensional structure of the invention has a plurality of electric units and a frame with a plurality of insulating columns. The electric units are vertically mounted in a plurality of stages between the insulating columns. Each insulating column has a plurality of insulators of a synthetic resin which are in a substantially linear arrangement at intervals; and a plurality of metallic spacers which are arranged at a distance between two adjacent insulators to couple them, and whereon the electric units can be mounted. The metallic spacers are electrically insulated from each other and the potential of each of the spacers is same as the potential of an electric unit to which the spacer is attached.