Y-△等效变换 U R R R 31 2 R 23 当R,=R2=R3=Ry,当R12=R23=R31=RA时: R.=3R r34Y- 等效变换 U12 U12 R2 1 2 3 R3 R1 R12 R23 R31 1 2 3 当R1=R2=R3=RY， R = 3RY RY = R 3 1 当R12  = R23 =R31 =R 时：