【简答题】如何使三相异步电动机反转?反相运转与反接制动有何区别?
【单选题】Chinese historians tried to ______ a balance between the data of history and their significance.
【简答题】旋转磁场的形成条件是什么?转动方向是由什么决定的?如何使三相异步电机反转?
【单选题】One of the most important results of research into ageing has been to pinpoint the significance of short-term memory. This faculty is easily (1)_____ as ageing advances. What seems to (2)_____ is that...
【多选题】依据生理变化特点,可将运动技能形成过程分为:
【单选题】One of the most important results of research into ageing has been to pinpoint the significance of short-term memory. This faculty is easily (1)_____ as ageing advances. What seems to (2)_____ is that...
【简答题】7 某绕线式三相异步电动机技术数据为:PN=60kW,nN=960r/min,E2N=200V,I2N=195A,λ=2.5。其拖动起重机主钩,当提升重物时电动机负载转矩TL=530N·m。 (1) 电动机工作在固有机械特性上提升该重物时,求电动机的转速; (2) 不考虑提升机构传动损耗,如果改变电源相序,下放该重物,下放速度是多少? (3) 若使下放速度为n=-280r/min,不改变电源相序,...