【判断题】【消耗次数:1】
一台6极船用柴油发电机,额定频率为50Hz,其额定转速为960r/min。
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错误
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相关题目
【判断题】 一台6极三相异步电动机接于50Hz的电源上,转速为960r/min。此时电 动机的转子电流频率为2Hz。
①  正确
②  错误
【单选题】 一台三相四极异步电动机,额定转差率是 0.04,若电源频率是50Hz,则电动机的转速为( )。
①  1440r/min
②  1450r/min
③  1000r/min
【单选题】 已知一台异步电动机转子的额定转速为1430r/min,那么这台电机的极对数为( )
①  2
②  4
③  6
④  1
【简答题】 两台三相异步电动机的电源频率为50Hz,额定转速分别为1440r/min和2910r/min,则它们的磁极数分别是多少?额定转差率分别是多少?
【单选题】 一台三相异步电动机的磁极对数p=2,电源频率为50Hz,电动机转速n=1440r/min,其转差率s为( )。
①  1%
②  2%
③  3%
④  4%
【单选题】 一台60Hz的变压器,如运行在同样额定电压的50Hz电网上,其铁耗将().
①  A.减少
②  B.增加
③  C.保持不变
④  D.减少1.2倍
【判断题】 一台变压器原设计的频率为50HZ,现将它接到60HZ的电网上运行,当额定电压不变时,铁芯中的磁通将减少。
①  正确
②  错误
【单选题】 发电机额定电压比线路额定电压( )。
①  高5℅
②  低5℅
③  相等
【单选题】 三相异步电动机的额定转速为 nN = 970r/min, 则其额定转差率为( )。
①  0.04
②  0.03
③  0.02
【单选题】 三相异步电机额定转速为980r/min。它的磁极对数P是()。
①  1
②  3
③  2
④  5
随机题目
【单选题】 26. It was _____ great shock to the world that two airplanes crashed into _____ World Trade Centre in New York on Sept.11.
①  a;/
②  the;the
③  a;the
④  /;the
【单选题】 29. We must remember that _____fashion is not the most important thing in _______ life.
①  /;the
②  /;/
③  the;/
④  the;the
【单选题】 22. The two old sisters,_______ so long,held each other and burst into tears.
①  beingseparated
②  havingbeenseparated
③  havingsepartated
④  hadbeensepartated
【单选题】 30. It _____ quite a few years _____ the accused was declared innocent and set free.
①  was;since
②  is;that
③  willbe;when
④  was;before
【单选题】 36._____ their real economic situations, they got some relief fund from the government.
①  Considering
②  Considered
③  Havingbeenconsidered
④  Beingconsidered
【单选题】 35.No matter how frequently _____ the works of Beethoven always attract a large number of people.
①  performing
②  performed
③  tobeperformed
④  beingperformed
【单选题】 38. In recent years much more emphasis has been put______ developing the students productive skills.
①  onto
②  in
③  over
④  on
【单选题】 39. A survey was carried out on the death rate of those who were infected by SARS, ________were surprising.
①  asresults
②  whichresults
③  theresultsofit
④  theresultsofwhich
【单选题】 34.I heard that you really had a wonderful time at Johns birthday party, _____?
①  didntI
②  didntyou
③  hadntyou
④  willyou
【单选题】 37._____ of water makes Death Valley a desert, but it is by no means devoid.
①  Lacking
②  Beinglack
③  Becauseoflack
④  Lack