一台三相4极、星形联结的异步电动机,额定值为:P N =1.7kW,U N =380V,I N =3.9A,n N =1445r/min。今拖动一恒转矩负载T L =11.38N·m连续运行,此时定子绕组平均已达到绝缘材料允许的温度上限。若电网电压下降为300V,在上述负载下电动机的转速为1400r/min,求此时电动机的铜耗为原来的多少倍?在此电网电压下该电动机能否长期运行下去(忽略励磁电流和机械损耗)?
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【单选题】In 1993, New York State ordered stores to charge a deposit on beverage (饮料) containers. Within a year, consumers had returned millions of aluminum cans and glass and plastic bottles. Plenty of compani...
A.
Beverage companies should be responsible for collecting and reusing discarded plastic soda bottles.
B.
Throwaways should be collected by the state for recycling.
C.
A fee should be charged on used containers for recycling.
D.
Consumers had to pay for beverage containers and could get their money back on returning them.
【单选题】Second Life for the Waste In 1993, New York State ordered stores to charge a deposit on beverage(饮料) containers.Within a year, consumers had returned millions.of aluminum cans, glass bottles and plast...
【单选题】In 1993, New York State ordered stores to charge a deposit on beverage (饮料) containers. Within a year, consumers had returned millions of aluminum cans and glass and plastic bottles. Plenty of compani...
A.
A fee should be charged on used containers for recycling.
B.
Throwaways should be collected by the state for recycling.
C.
Consumers had to pay for beverage containers and could get their money back on returning them.
D.
Beverage companies should be responsible for collecting and reusing discarded plastic soda bottles.
【简答题】Passage Four:Questions 36 to 40 are based on the following passage.In 1993. New York State ordered stores to charge a deposit on beverage (饮料) containers. Within a year. Consumers had returned million...
【单选题】In 1993, New York State ordered stores to charge a deposit on beverage(饮料) containers. Within a year, consumers had returned millions of aluminum cans and glass and plastic bottles. Plenty of companie...