A.45hz~50.1hz B.474hz~50hz C.48hz~49.5hz D.49.5hz~50.5hz
A.49hz~50.1hz B.49.4hz~50.1hz C.49.5hz~50.2hz D.49.5hz~50.5hz
A.輸電方式 B.電壓等級 C.線路長度 D.回路數(shù)