| 摘要 |
PURPOSE:To attain small size and light weight and to improve the reliability by providing a gapless arrestor in parallel with each thyristor via an impedance in a thyristor valve where thyristors having a self-trigger function to a forward voltage are connected in series or in series and parallel for the plural number. CONSTITUTION:As the thyristors, n-set of free thyristors having self-trigger function (VBO) and each thyristor and a gapless arrestor are connected via the impedance. The protection level (VAr) of each gapless arrestor is set lower than the voltage (VBO) of each VBO free thyristor subject to VBO. Moreover, the impedance (Z) 5 is decided so as to establish the following equation, where I1 is the minimum running current flowing to the thyristor valve; VBO=VAr+(I1XZ). If an overvoltage is applied to the thyristor valve, the gapless arrestors 3-1- 3-n are operated in series to the overvoltage applied to the entire thyristor valve so as to protect the VBO free thyristors from the overvoltage. |
