问题 单项选择题

<某工程项目设计中有一台同步电动机,额定功率Pe=1450kW,额定容量Se=1.9MVA,额定电压Ue=6kV,额定电流Ie=183A,起动电流倍数kiq=5.9,额定转速ne=500r/min,折算到电动机轴上的总飞轮转矩GD=80kN.m2,电动机全电压起动时的转矩相对值,电动机起动时的平均转矩相对值,生产机械的静阻转矩,6kV母线短路容量Sdl=46MVA,6kV母线其他无功负载,要求分别计算及讨论有关该同步电动机的起动电压及起动时间,请回答下列问题,并列出解答过程。

下列影响同步电动机起动时间的因素,哪一项是错误的?()

A.电动机额定电压

B.电动机所带的负载阻矩相对值

C.折合到电机轴上的飞轮距

D.电动机起动时定子端电压相对值

答案

参考答案:A

判断题
单项选择题

A punctual person is in the habit of doing a thing at the proper time and is never late in keeping an appointment.
The unpunctual man, on one hand, never does what he has to do at the proper time. He is always in a hurry and in the end loses both time and his good name. A lost thing may be found again, but lost time can never be regained. Time is more valuable than material things. In fact, time is life itself. The unpunctual man is for ever wasting and mismanaging his most valuable asset as well as other’s. The unpunctual person is always complaining that he finds no time to answer letters, or return calls or keep appointments promptly. But the man who really has a great deal to do is very careful of his time and seldom complains of want of it. He knows that he can not get through his huge amount of work unless he faithfully keeps every piece of work when it has to be attended to.
Failure to be punctual in keeping one’s appointments is the sign of disrespect towards others. If a person is invited to dinner and arrives later than the appointed time, he keeps all the other guests waiting for him. Usually this will be regarded as a great disrespect to the host and all other guests present.
Unpunctuality, moreover, is very harmful when it comes to do one’s duty, whether public or private. Imagine how it would be if those who are put in charge of important tasks failed to be at their proper place at the appointed time. A man who is known to be habitually unpunctual is never trusted by his friends or fellow men.

Which of the following statements best describes the harm of unpunctuality

A. If you are an unpunctual person, you cannot be in charge of any important task.
B. If your friends know that you are unpunctual, they may not see you again.
C. Unpunctuality may bring about heavy losses for both public and private affairs.
D. Unpunctuality may make you miss a lot of appointments and lose friends.