△接:用电压表示电流 Y接:用电流表示电压 Y 12△ 31△ R R 12Y R R 2Y 3Y+ 2 R 3 3Y u12yRly-Ri2y I1△=12△12-l31△k31 i2△=23△R2312△R12(1) u23yR2l2Y-R (2) i3△=31△R31-u23△R23 Y2Y3Y 0Y接: 用电流表示电压 u12Y=R1 i1Y–R2 i2Y 接: 用电压表示电流 i1Y+i2Y+i3Y = 0 u23Y=R2 i2Y – R3 i3Y i3 =u31 /R31 – u23 /R23 i2 =u23 /R23 – u12 /R12 R12 R31 R23 i3  i2  i1 1 2 3 + + + – – – u12 u23 u31 R1 R2 R3 i1Y i2Y i3Y 1 2 3 + + – + – – u12Y u23Y u31Y i1 =u12 /R12 – u31 /R31 (1) (2)