This series products are used in three-phase oil immersed electric transformers with frequency of 50Hz, rated voltage of 10kv、35KV. When there isn’t excitation, changing original winding’s circle number of transformer can change transformation directly so as to regulate voltage of next level. This series products have features of novel and compact structure, sensible operation, auto-lock function as well as position limitation structure. And they have strong click anti-pressure ability and overload ability, safe installation, safe operation and safe maintenance, so they are the ideal accessories of new-type S9 and S11 series energy-saving transformers. model: