Y-Y connected Z bB ad 十 bn a4- bB bn⊥Fam∠-120=ia∠-1200 P an∠+120 aA∠+120 Nn A+bB+ 0Y-Y connected p an aA Z V I • • =   120 120 =  −  − = = • • • • a A p a n p b n b B I Z V Z V I   120 120 =  +  + = = • • • • a A p a n p cn cC I Z V Z V I = + + = 0 • • • • I Nn I aA I bB I cC I aA • I bB • I cC • V an • V bn • V cn •    a b c n • V bn • + + + − − −    A B C • Z p Z p Z p N V cn • V an •