Abstract: In order to solve the problem of switching overvoltage for CRAFT, an optimal design is put forward to suppress overvoltage, which aims to enable the converter thyristor work normal. When the vacuum circuit breaker on the grid side of CRAFT rectifier transformer, an overvoltage appeared on the secondary side of the transformer. Compared the conventional way to suppress overvoltage, the overvoltage can be limited effectively by accurate calculation, as a result, the switching voltage is improved. In addition, the problem of electric elements waste can be avoided. All the work has been done provides a useful reference in optimization design of suppression switching overvoltage for CRAFT, which can protect the power supply and maintain the system run normal.

Keywords: CRAFT; Converter module; Operating overvoltage; Cophase counter parallel connection; No-load transformer breaking; Optimal RC snubber protection