发布时间 : 星期六 文章15级题库 电机与拖动基础试题库及答案更新完毕开始阅读84ea3ede2dc58bd63186bceb19e8b8f67c1cefcf
2) s?RP?r2?sg?0.4?0.023?0.03?1?0.552
r20.023 n?(1?s)n1?(1?0.552)?600?268.8r/min
6、一台△联结的4极三相异步电动机,UN?380V,nN?1470r/min
'r1?r2'?0.072?,X1?X2?0.06?,fN?50Hz试求:全压起动时的定子电流(略空载电流)及其功率因数、起动转矩倍数;Y/△起动时的起动电流、起动转矩。 解:全压起动时的定子电流、功率因数:
Ist?相?cos?1?UN?(r1?r)?(X1?X)r1?r2'(r1?r)?X1?X'22'22'22?380(0.072?0.072)?(0.2?0.2)0.072?0.072(0.072?0.072)?(0.2?0.2)222?893.84A
?0.3384
? 22?2求起动转矩倍数:
sN?n1?nN1500?1470??0.02 n115002'm1pU1r2s
TN?2 2?f1r1?r2's?X1?X2 ?????23?23802?0.072/0.02??727.68N?m
0.0722??2??50?(0.072?)?(0.2?0.2)2?0.02??3?2?3802?0.072Tst??1098.64N?m222??50(0.072?2)?(0.2?2)??
起动转矩倍数:
Y/△起动时的起动电流、起动转矩:
KM?Tst1098.64??1.51TN727.68I'st? Tst'?
Ist?3?893.84??516A 33Tst1098.64??366.2N?m 33