Compared with conventional protection for generator-transformer unit, protection configured double sets has different demands in many aspects including transducer configuration, scheme of panel design, protection operating objects and its connecting status in secondary circuit. Microcomputer-based protections produced by dissimilar manufacturers are in different applications. Taking an example of series CSC-300 protection for generator-transformer unit produced by Beijing Sifang Automation Co., Ltd, the paper introduces and summaries above-mentioned different demands and applications, combining standard design of new-built 300MW generator-transformer unit in Inner Mongolian area.