A.0.3一50S B.0.4一50s C.0.5一60s D.0.5一70s
A.20%一50% B.20%一70% C.30%一80% D.30%一70%
A.功率因數(shù)可調(diào)節(jié) B.轉(zhuǎn)子用直流勵磁損耗小,效率高 C.需要交、直流兩種電源 D.轉(zhuǎn)速可調(diào)節(jié)