【单选题】As there is less and less coal and oil, scientists are exploring new ways of making use ofenergy,
A.
6. As there is less and less coal and oil, scientists are exploring new ways of making use of energy, such as sunlight, wind and water for power and fuel. A.primary
【简答题】有一台三相异步电动机,其铭牌数据如下: P N /kW n N /r · min -1 U N /V η N × 100 cos φ N I st /I N Tst/T N T max /T N 接法 40 1470 380 90 0.9 6.5 1.2 2.0 △ 1、当负载转矩为 250N · m 时,试问在 U=U N 和 U`=0.8U N 两种情况下电动机能否启动? 2、 欲采用Y-△换...