"-ist(noun)"means()
A.person who does something
B.person who says something
C.person who believes in something
D.person who changes something
PERSONWHODOESSOMETHINGPERSONWHOBELIEVESINSOMETHING
A.person who does something
B.person who says something
C.person who believes in something
D.person who changes something
PERSONWHODOESSOMETHINGPERSONWHOBELIEVESINSOMETHING
In English the most productive type of conversion is conversion
A.from verb to adjective.
B.from adjective to noun.
C.from noun to adjective.
D.from noun to verb.
A.Verbs.
B.Adjectives.
C.Adverbs.
D.Nouns.
已知Y132S-4型三相异步电动机的额定技术数据如表7-1所示。
功率 | 转速 | 电压 | 效率 | 功率因数 | Ist/IN | Tst/TN | Tmax/TN |
5.5kW | 1440r/min | 380V | 85.5% | 0.84 | 7 | 2.2 | 2.2 |
电源频率为50Hz,试求额定状态下的转差率sN,电流IN和转矩TN,以及启动电流Ist,启动转矩Tst,最大转矩Tmax。
某三相笼型异步电动机,其铭牌数据如下:三角形联结,UN=380V,IN=19.9A,PN=10kW,nN=1450r/min,Tst/TN=1.4,Ist/IN=7。若负载转矩为20N·m,电源允许最大电流为60A,试问应采用直接起动还是采用Y-Δ换接方法起动,为什么?