如果三相负载是对称的,即Za=Zb=Zc=2=Z|∠2 U.∠0°U 则: A U.∠-1209U7 B B 2∠(-120°-9:) U.∠120°U C C =P∠(120°-2) 2∠q 中线中没有电流,即KN=A+lB+lc=0 三相功率:P=3Pn=3 U,In cos2=√311cos Q=√3U1l1sin S=P+O 跳转到第一页跳转到第一页 (120 ) 120 ( 120 ) 120 0 C C B B A A z p z p z p z p z p z p Z U Z U Z U I Z U Z U Z U I Z U Z U Z U I = − = = = − − − = = = − = = p p p z l l z P = 3P = 3U I cos = 3U I cos I N = I A + I B + I C = 0 中线中没有电流,即 如果三相负载是对称的,即 a b c z Z = Z = Z = Z =| Z | 则: 三相功率: z Q = 3Ul I l sin l l S P Q 3U I 2 2 = + =