【单选题】
一般额定电压为380V的三相异步电动机，用500V的兆欧表测量绝缘电阻应大于___MΩ才可以使用。
A. 0.1
B. 0.2
C. 0.5
D. 1
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相关试题
【单选题】
触电者心跳停止，同时呼吸也停止或呼吸微弱，应立即进行___抢救。
A. 人工呼吸
B. 胸外胸脏按压
C. 心肺复苏
D. 电话联系医生
【单选题】
将电气装置中平时不带电但可能因绝缘损坏而带上危险的对地电压的外漏导电部分与大地电气连接，采用___。
A. 保护接地
B. 重复接地
C. 过电压接地
D. 系统接地
【单选题】
电阻并联电路中的总电流等于各电阻中的电流___。
【单选题】
配电装置的长度超过___m时，屏后应有两个通向本室或其他房间的出口，其距离不宜大干15m。
【单选题】
通电时间与电流的乘积大于___mA.s时就有生命危险。
【单选题】
半导体点温计是一种测量范围为___℃的携带式测量仪表。
A. 0～60
B. 60～100
C. 0～100
D. 0～150
【单选题】
施工现场专用临时用电，中性点直接接地的供电系统，必须采用___系统。
A. TT
B. IT
C. TN-C
D. TN-S
【单选题】
I类电器设备应有良好的接地措施，其保护线应采用截面积___mm2以上的多股软铜线。
A. 0.5～0.75
B. 0.75～1.5
C. 1.5～2.5
D. 2.5
【单选题】
低压架空线路的导线与建筑物之间的最小距离，不应小于___m。
A. 6.5
B. 5.5
C. 3.5
D. 2.5
【单选题】
电动机的启动转矩与电压的平方___。
A. 成正比
B. 成反比
C. 1/3
D. 1／√3
【单选题】
RCD检测机构的任务就是将___信号检测出来，然后送给判断机构。
A. 剩余电流
B. 短路电流
C. 泄漏电流
D. 脉动电流
【单选题】
所谓安全电源，指正常工作时电压值在安全特低电压范围内，具有___。
A. 采用安全电压隔离变压器
B. 交流电压低于50V
C. 直流电压低于70V
D. 1、1隔离变压器
【单选题】
黄／绿双色线在任何情况下，只能用于保护线或___线，不得挪作他用。
【单选题】
I类携带式电气设备的绝缘电阻不应低于___MΩ。
【单选题】
线路的停送电均应按照值班调度员的命令执行，或按有关单位___的人员的命令执行，严禁约时停送电。
A. 电话通知
B. 口头商
C. 书面指定
D. 口头指定
【单选题】
先估计被测电阻大致的数值，选择合适的___。
【单选题】
E类火灾场所（物体带电燃烧的火灾）的灭火器，其最大保护距离不应低于___m。
A. 6～7
B. 7～8
C. 8～9
D. 9～15
【单选题】
利用绕原点以角速度逆时针旋转的矢量来表示正弦量的方法称___。
A. 解析法
B. 曲线图法
C. 旋转矢量法
D. 复数法
【单选题】
潮湿的地沟内使用的手持照明灯，应采用___V的安全工作电压作为电源。
【单选题】
接闪网和接闪带不可采用镀锌圆钢或扁钢，截面积不小于___mm2。
【单选题】
在室内高压设备上工作，应在工作地点两旁间隔和对面间隔的遮拦上和禁止通行的过道上悬挂___标示牌。
A. 禁止合闸，有人工作！
B. 止步，高压危险！
C. 禁止攀登，高压危险！
D. 从此上下！
【单选题】
电桥使用完毕，应先将___按下。
A. 电源按钮
B. 检流计按钮
C. 电压按钮
D. 电流按钮
【单选题】
10kV及以下架空电力线路杆梢的位移不应大于杆梢直径的___。
A. 1/3
B. 1/2
C. 1/4
D. l/5
【单选题】
新型管型避雷器几乎没有续流，适用于___的地区。
A. 弱绝缘保护
B. 出现保护
C. 雷电活动频繁
D. 变压器保护
【单选题】
铁壳开关在控制电路中，也可用于不频繁启动___kW以下三相异步电动机。
【单选题】
电力电缆1kV及以下可以用1000V兆欧表测其绝缘，其绝缘电阻一般不低于___MΩ。
【单选题】
运行中的FS型避雷器的绝缘电阻不应低于___MΩ。
A. 2000
B. 1000
C. 500
D. 200
【单选题】
电动机每1kV工作电压，绝缘电阻不得低于___MΩ。
【单选题】
变极式三相异步电动机，由于接线复杂，一般做成最多___速度。
【单选题】
静电接地装置应当连接牢靠，一般采用___。
【单选题】
E级绝缘的电动机，其绝缘材料的耐热极限温度___℃。
A. 90
B. 105
C. 120
D. 130
【单选题】
巡视配电装置，进出高压室，必须随手将门___。
【单选题】
胶壳开关当作为隔离开关使用时，刀开关的额定电流要___线路实际工作电流。
A. 大于
B. 小于
C. 等于或稍大于
D. 等于
【单选题】
I类电动工具，这类工具在防止触电的保护依靠___。
A. 特低电压供电
B. 基本绝缘
C. 附加绝缘
D. 加强绝缘
【单选题】
三相异步电动机在额定状态下运行时，额定转差率约在___之间。
A. 0.1～0.2
B. 0.2～0.3
C. 0.01～0.05
D. 0.06～0.1
【单选题】
接闪杆杆长为1～2m时且采用镀锌钢管时，钢管直径为___mm。
【单选题】
通常把因其心室颤动的___电流值则作为致命电流界限。
【单选题】
IP44表示电动机外壳防护方式是___一
A. 开启式
B. 防护式
C. 封闭式
D. 隔爆式
推荐试题
【单选题】
Having practiced so many times, I feel very ___ of my ability to deliver the presentation successfully.
A. satisfied
B. incredible
C. confident
D. enthusiastic
【单选题】
The university decided to increase the ___ of the lecture hall, which has only 200 seats.
A. ability
B. capacity
C. facility
D. faculty
【单选题】
Smart phones – with cameras and color screens – can ___ images and data using wireless network technology.
A. evolve
B. depart
C. transmit
D. assure
【单选题】
Don’t take someone you get to know from the Internet to your house no matter how ___ he sounds.
A. bold
B. genuine
C. flexible
D. available
【单选题】
This kind of exercise will ___ your creativity, renew your energy, and unlock your potential.
A. bind
B. yield
C. embrace
D. stimulate
【单选题】
I’ll be happy to help you, ___ you won’t take up too much of my time.
A. as well as
B. as long as
C. as far as
D. as soon as
【单选题】
We teachers do not consider it wise to ___ our students with all sorts of exams, tests and quizzes.
A. load
B. annoy
C. sample
D. explore
【单选题】
He makes his students ___ knowledge through various kinds of interesting activities.
A. study
B. learn
C. achieve
D. acquire
【单选题】
For years, scientists have debated the ___ dangers of building another nuclear plant after the terrible accident.
A. available
B. potential
C. fascinating
D. genuine
【单选题】
It was a worthwhile attempt ___ it failed to achieve its purpose that we had hoped for.
A. in the end
B. now that
C. all at once
D. even though
【单选题】
Travel in space can be very exciting; ___, it can also be boring and lonely at times.
A. so
B. however
C. thus
D. therefore
【单选题】
Politicians should not ___ in business affairs that might affect their political judgment.
A. engage
B. embrace
C. depart
D. treasure
【单选题】
I wish to ___ a master’s degree in electric engineering after I graduate from college.
A. pledge
B. explore
C. pursue
D. approach
【单选题】
There is no greater importance ___ cultivating independence in children.
A. in
B. than
C. of
D. with
【单选题】
He has made it very clear ___ we should observe the new rules.
A. what
B. which
C. those
D. that
【单选题】
It was when I read his letter ___ I realized he had given me huge help.
A. that
B. then
C. before
D. after
【单选题】
Don’t worry too much, Jane. Your son ___ home already. Let’s go back and check it out.
A. returned
B. will return
C. has returned
D. may have returned
【单选题】
I believe friendship is an essential element of making a healthy, ___ life.
A. flexible
B. rewarding
C. wealthy
D. inquisitive
【单选题】
___ they have written about the behaviors of animals is hardly anything new.
A. That
B. This
C. What
D. Which
【单选题】
No other drugs are as good as this one; it must have been based on a(n) ___ formula (配方).
A. enormous
B. stimulating
C. unique
D. overwhelming
【单选题】
Mothers tend to be too ___ toward their children. They should let them see more of the worl D.
A. hopeful
B. protective
C. modest
D. encouraging
【单选题】
The investigation ___ evidence of a large-scale illegal trade in wild birds.
A. uncovered
B. outweighed
C. overwhelmed
D. evolved
【单选题】
Poor Laura! I feel so sorry for her. When she fell, she hurt her arm and, ___, broke her glasses.
A. in advance
B. in addition
C. over time
D. on the other hand
【单选题】
Showing some sense of humor can be a(n) ___ way to deal with some stressful situations.
A. genuine
B. available
C. effective
D. favorite
【单选题】
It will be worth the efforts even if you fail; the rewards you ___ will be great.
A. reap
B. boast
C. assure
D. cultivate
【单选题】
He suggested transporting the supplies by air. But it is absolutely ___, for it will cost too much.
A. unusual
B. uncertain
C. impractical
D. impressive
【单选题】
The newspaper didn’t mention the ___ of the damage caused by the fire.
A. range
B. level
C. extent
D. quantity
【单选题】
Do you ___ her novels as serious literature or as mere entertainment?
A. classify
B. notify
C. simplify
D. justify
【单选题】
He doesn’t ___ of buying a house this year because the bank has refused to lend him any money.
A. afford
B. make the most
C. run out
D. stand a chance
【单选题】
If you don’t ___ cooking today, we can go out to eat at the new restaurant.
A. would like
B. go on with
C. feel like
D. figure out、
【单选题】
Bullying (恃强欺弱) can ___ a climate of fear and anxiety in school, and prevent students from focusing on their schoolwork.
A. keep back
B. give rise to
C. feel like
D. make use of
【单选题】
Science can now ___ many things which were thought to be mysterious by ancient people.
A. care for
B. lay out
C. account for
D. set up
【单选题】
The school has ___ many after-class activity groups for the pupils to make their spare time more colorful.
A. set up
B. set off
C. set out
D. set down
【单选题】
When he was a small kid, he ___ from his peers because he could read fast and remember whatever he rea D.
A. showed off
B. worked out
C. stood out
D. straightened up
【单选题】
The fall in the number of deaths from heart disease is generally ___ improvements in diet.
A. put up with
B. attributed to
C. added to
D. replaced with
【单选题】
We can be partners for now, but ultimately you have to ___ to develop a new software for our project.
A. keep up
B. fire off
C. make sense
D. take the lead
【单选题】
Emotional Intelligence (情商) could be of practical use in many ___ such as how companies decide which job applicant to hire, how parents should raise their children, how schools should teach the students, and so on.
A. aspects
B. disciplines
C. structures
D. opportunities
【单选题】
The teacher should praise students for their correct answers and also suggest ___ possibilities.
A. unlimited
B. unique
C. alternative
D. essential
【单选题】
In some classrooms, desks are arranged in a U-shape, so the teacher can ___ easily with the students.
A. interrupt
B. interact
C. interpret
D. interview
【单选题】
Computer technology ___ individuals to educate themselves and adapt to a constantly changing job market.
A. lets
B. makes
C. enables
D. provides
