A surgical generator for providing a drive signal to a surgical device may have a receptacle assembly having a receptacle body, a flange and a central protruding portion. The outer periphery of the central protruding portion may have at least one curved section and at least one linear section. Additionally, a surgical instrument may comprise an electrical connector assembly having a flange. The flange may comprise at least one curved section and at least one linear section. In some embodiments, A surgical instrument system may comprise a surgical generator, a surgical instrument comprising a connector assembly, and an adapter assembly operatively coupled to the receptacle assembly and the connector assembly.