刷题
导入试题
【单选题】
在自控系统中不仅要求异步测速发电机输出电压与转速成正比,而且也要求输出电压与励磁电源同相位。相位误差可在___,也可在输出绕组电路补偿。
A. 输出回路中并联电感进行补偿
B. 励磁回路中并联电容进行补偿
C. 励磁回路中串联电容进行补偿
D. 输出回路中串联电感进行补偿
查看试卷,进入试卷练习
微信扫一扫,开始刷题
答案
C
解析
暂无解析
相关试题
【单选题】
将变频器与PLC等上位机配合使用时,应注意___。
A. 使用共同地线、最好接入噪声滤波器、电线各自分开
B. 不使用共同地线、最好接入噪声滤波器、电线汇总一起布置
C. 不使用共同地线、最好接入噪声滤波器、电线各自分开
D. 不使用共同地线、最好不接入噪声滤波器、电线汇总一起布置
【单选题】
变频器网络控制的主要内容是___。
A. 启停控制、转向控制、显示控制
B. 启停控制、转向控制、电动机参数控制
C. 频率控制、显示控制
D. 频率控制、启停控制、转向控制
【单选题】
变频器启停方式有面板控制、外部端子控制、通信端口控制。当与PLC配合组成远程网络时,主要采用___方式。
A. 面板控制
B. 外部端子控制
C. 通信端口控制
D. 脉冲控制
【单选题】
U/f控制方式是变频器的基本控制方式。对于风机和泵类负载转矩补偿应选择在额定电压和基本频率下进行___。
A. 线性补偿
B. 分段补偿
C. 平方率补偿
D. 以上均可
【单选题】
恒转矩负载变频调速的主要问题是调速范围能否满足要求。典型的恒转矩负载有___。
A. 起重机、车床
B. 带式输送机、车床
C. 带式输送机、起重机
D. 薄膜卷取机、车床
【单选题】
变频器连接同步电动机或连接几台电动机时,变频器必须在___特性下工作。
A. 恒磁通调速
B. 调压调速
C. 恒功率调速
D. 变阻调速
【单选题】
变频器连接同步电动机或连接几台电动机时,变频器必须在___特性下工作。
A. 免测速矢量控制
B. 转差率控制
C. 矢量控制
D. U/f控制
【单选题】
电动机的启动转矩必须大于负载转矩。若软启动器不能启动某负载,则可改用的启动设备是___。
A. 采用内三角接法的软启动器
B. 采用外三角接法的软启动器
C. 变频器
D. 星一三角启动器
【单选题】
电动机停车要精确定位,防止爬行,变频器应采用___的方式。
A. 能耗制动加直流制动
B. 能耗制动
C. 直流制动
D. 回馈制动
【单选题】
负载不变情况下,变频器出现电流故障,原因可能是___。
A. 负载过重
B. 电源电压不稳
C. 转矩提升功能设置不当
D. 斜波时间设置过长
【单选题】
三相单三拍运行、三相双三拍运行、三相单双六拍运行。其通电顺序分别是___
A. A-B-C-A,AB-BC-CA-AB,A-AB-B-BC-C-CA-A
B. AB-BC-CA-AB,A-B-C-A,A-AB-B-BC-C-CA-A
C. A-B-C-A,A-AB-B-BC-C-CA-A,AB-BC-CA-AB
D. A-AB-B-BC-C-CA-A,A-B-C-A,AB-BC-CA-AB
【单选题】
步进电动机双三拍与单三拍工作方式比较,前者___。
A. 电磁转矩小、易产生失步
B. 电磁转矩小、不易产生失步
C. 电磁转矩大、易产生失步
D. 电磁转矩大、不易产生失步
【单选题】
步进电动机的角位移或线位移与___。
A. 脉冲数成正比
B. 脉冲频率f成正比
C. 驱动电源电压的大小
D. 环境波动相关
【单选题】
步进电动机的驱动电源由运动控制器,脉冲分配器和功率驱动级组成,各相通断的时序信号由___。
A. 运动控制器给出
B. 脉冲分配器给出
C. 功率驱动器给出
D. 另外电路给出
【单选题】
步进电动机应是___。
A. 索耶式直线步进电动机
B. 水磁式步进电动机
C. 反应式步进电动机
D. 混合式步进电动机
【单选题】
旋转式步进电动机有多种。现代应用最多的是___步进电动机。
A. 反应式
B. 永磁式
C. 混合式
D. 索耶式
【单选题】
步进电动机的驱动方式有多种,___目前普遍应用。由于这种驱动在低频时电流有较大的上冲,电动机低频噪声较大,低频共振现象存在,使用时要注意。
A. 细分驱动
B. 单电压驱动
C. 高低压驱动
D. 斩波驱动
【单选题】
步进电动机带额定负载不失步启动的最高频率,称为步进电动机的___。
A. 启动频率
B. 工作频率
C. 额定频率
D. 最高频率
【单选题】
步进电动机的启动和停止频率应考虑负载的转动惯量,对于大转动惯量的负载,启动和停止频率应选___。
A. 低一些
B. 高一些
C. 中等
D. 0
【单选题】
高分辨率且高精度的办公自动化设备中,要求步进电动机的步距角小,较高的启动频率,控制功率小,良好的输出转矩和加速度,则应选___。
A. 反应式直线步进电动机
B. 永磁式步进电动机
C. 反应式步进电动机
D. 混合式步进电动机
【单选题】
为防止在高频区工作产生失步现象,步进电动机工作时应根据其___确定在某一负载时的最高工作频率。
A. 矩频特性
B. 额定电流
C. 额定电压
D. 静态步距角误差
【单选题】
基本步距角θs、转子齿数ZR,通电循环拍数N。三者的关系是___。
A. ZR一定时,θs与N成反比
B. ZR一定时,θs与N成正比
C. N一定时,θs与ZR成正比
D. θs一定时,N与ZR成正比
【单选题】
三相六拍运行比三相双三拍运行时___。
A. 步距角不变
B. 步距角增加一半
C. 步距角减少一半
D. 步距角增加一倍
【单选题】
三相双三拍运行,转子齿数Zn=40的反应式步进电动机,转子以每拍___的方式运转。
A. 5°
B. 9°
C. 3°
D. 6°
【单选题】
步进电动机的速度与___有关。
A. 环境温度
B. 负载变化
C. 与驱动电源电压的大小
D. 脉冲频率
【单选题】
步进电动机的转速n或线速度V只与___有关。
A. 电源电压
B. 负载大小
C. 环境条件的波动
D. 脉冲频率f
【单选题】
步进电动机的___与脉冲频率/成正比。
A. 线位移或角位移
B. 线位移或转速n
C. 转速n或线速度V
D. 转速n或角位移
【单选题】
步进电动机的角位移或线位移与___
A. 脉冲数成正比
B. 脉冲频率f成正比
C. 驱动电源电压的大小成正比
D. 环境波动相关
【单选题】
有电枢电压,电动机嗡嘴响但不转,一会出现过流跳闸。故障原因可能是___
A. 电动机气隙碰通不饱和
B. 电动机气隙磁通饱和
C. 高碳电路损坏或没有加励磁
D. 电枢电压过低
【单选题】
直流电动机运行中转速突然急速升高并失控。故障原因可能是___。
A. 突然失去励磁电流
B. 电枢电压过大
C. 电枢电流过大
D. 励磁电流过大
【单选题】
直流电动机启动时设加励磁,电动机会过热烧毁,原因是电动机不转时___导致电枢电流很大。
A. 电枢回路的电阻很小
B. 电枢回路的反电动势很高
C. 电枢电压高
D. 电枢回路的反电动势为零
【单选题】
直流测速发电机输出电压与转速之间并不能保持确定的线性关系。其主要原因是___。
A. 电枢电阻的压降
B. 电枢电流的去磁作用
C. 负载电阻的非线性
D. 电刷的接触压降
【单选题】
双闭环直流调速系统调试中,出现转速给定值U.达到设定最大值时,而转速还未达到要求值,应___。
A. 逐步减小速度负反馈信号
B. 调整速度调节器ASR限幅
C. 调整电流调节器ACR限幅
D. 逐步减小电流负反馈信号
【单选题】
调速系统开机时电流调节器ACR立刻限幅,电动机速度达到最大值,或电动机忽转忽停出现振荡。可能的原因是___。
A. 系统受到严重干扰
B. 励磁电路故障
C. 限幅电路没有整定好
D. 反馈极性错误
【单选题】
直流电动机弱磁调速时,防飞车故障,应加___。
A. 失磁保护电路
B. 防磁饱和电路
C. 过压保护电路
D. 过流保护电路
【单选题】
直流电动机弱磁调速时,励磁电路接线务必可靠,防止发生___。
A. 运行中失磁造成飞车故障
B. 运行中失磁造成停车故障
C. 启动时失磁造成飞车故障
D. 启动时失磁造成转速失控故障
【单选题】
在转速电流双闭环调速系统中,调节给定电压,电动机转速有变化,但电枢电压很低。此故障的可能原因是___。
A. 主电路品闸管损坏
B. 品闸管触发角太小
C. 速度调节器电路故障
D. 电流调节器电路故障
【单选题】
在转速电流双闭环调速系统中,调节速度给定电压,电机转速不变化。此故障的可能原因是___。
A. 品闸管触发电路故障
B. PI调节器限幅值整定不当
C. 主电路晶闸管损坏
D. 电动机励磁饱和
【单选题】
品闸管一电动机调速系统的主回路电流断续时,开环机械特性___。
A. 变软
B. 变硬
C. 不变
D. 电动机停止
【单选题】
双闭环调速系统中转速调节器一般采用Pl调节器,I参数的调节主要影响系统的___
A. 稳态性能
B. 动态性能
C. 静差率
D. 调节时间
推荐试题
【填空题】
in sb. 's words,count on,make sense of ,reserve for, shield from,call on, sum up, relate to ,in need, be/ get caught up in We will continue to care for those [ ] and work to establish a society that is generous and prosperous
【填空题】
in sb. 's words,count on,make sense of ,reserve for, shield from,call on, sum up, relate to ,in need, be/ get caught up in Many people [ ]careers and raising kids so that they forget that their marriages also need to be taken good care of
【填空题】
in sb. 's words,count on,make sense of ,reserve for, shield from,call on, sum up, relate to ,in need, be/ get caught up in My most favorite program is the one that deals with scientific subjects that ordinary people can [ ]
【填空题】
in sb. 's words,count on,make sense of ,reserve for, shield from,call on, sum up, relate to ,in need, be/ get caught up in Finally, I would like to [ ]by saying that it has been a tremendous pleasure to work with you all
【填空题】
in sb. 's words,count on,make sense of ,reserve for, shield from,call on, sum up, relate to ,in need, be/ get caught up in He is a person that you always [ ]when you need help.
【填空题】
in sb. 's words,count on,make sense of ,reserve for, shield from,call on, sum up, relate to ,in need, be/ get caught up in This restaurant is very popular because it has some separate, smaller rooms [ ] families with small children
【填空题】
in sb. 's words,count on,make sense of ,reserve for, shield from,call on, sum up, relate to ,in need, be/ get caught up in Betty loves reading.[ ],“Reading is the most wonderful thing in the world.”
【填空题】
open the door to,In advance,all at once,reap the benefits (of), make the most of,over time, get by, stand a chance (of),remind of, take pleasure in, Every one of you has made a contribution and I [ ] knowledging what each of you has done to make this academic convention such a success.
【填空题】
open the door to,In advance,all at once,reap the benefits (of), make the most of,over time, get by, stand a chance (of),remind of, take pleasure in They all tried to talk [ ], but I couldn't hear anything they said
【填空题】
open the door to,In advance,all at once,reap the benefits (of), make the most of,over time, get by, stand a chance (of),remind of, take pleasure in, Yellow flowers in the field always [ ] me [ ] my childhood in the countryside
【填空题】
open the door to,In advance,all at once,reap the benefits (of), make the most of,over time, get by, stand a chance (of),remind of, take pleasure in, We have been practicing for so long and so hard that our team should [ ]winning the game
【填空题】
open the door to,In advance,all at once,reap the benefits (of), make the most of,over time, get by, stand a chance (of),remind of, take pleasure in, Research on genes will [ ] exciting new medical treatments.,
【填空题】
open the door to,In advance,all at once,reap the benefits (of), make the most of,over time, get by, stand a chance (of),remind of, take pleasure in, My family [ ] on my father's unemployment benefit after he lost his job
【填空题】
open the door to,In advance,all at once,reap the benefits (of), make the most of,over time, get by, stand a chance (of),remind of, take pleasure in, Many subway riders read books or listent music in order to [ ] their time on the way to work
【填空题】
open the door to,In advance,all at once,reap the benefits (of), make the most of,over time, get by, stand a chance (of),remind of, take pleasure in, In order to make sure he would be able to attend the meeting, I called him up two weeks [ ]
【填空题】
open the door to,In advance,all at once,reap the benefits (of), make the most of,over time, get by, stand a chance (of),remind of, take pleasure in, In order to [ ]physical exercise, you have to exercise regularly and for at least half an hour each time
【填空题】
embarrass,polish, emotional, etticiency,curb ,await, donation ,dump,stuff ,historical Mary was a careful speaker, every word seemed to have been [ ] before it was allowed to escape through her lips
【填空题】
embarrass,polish, emotional, etticiency,curb ,await, donation ,dump,stuff ,historical He has a special feeling for the brilliant birds, and each spring he eagerly [ ] their return
【填空题】
embarrass,polish, emotional, etticiency,curb ,await, donation ,dump,stuff ,historical Thanks to the [ ] of air transport,everyone is free to go anywhere at any time
【填空题】
embarrass,polish, emotional, etticiency,curb ,await, donation ,dump,stuff ,historical John believes that the [ ] of food to the hungry is more helpful than giving money
【填空题】
embarrass,polish, emotional, etticiency,curb ,await, donation ,dump,stuff ,historical When she heard it was snowing in the city they were going to, she [ ] two more sweaters into her bag.
【填空题】
embarrass,polish, emotional, etticiency,curb ,await, donation ,dump,stuff ,historical During our stay in Europe we visited many places of [ ] interest, including several castles
【填空题】
embarrass,polish, emotional, etticiency,curb ,await, donation ,dump,stuff ,historical The wedding ceremony of my sister was a very [ ] experience for our family
【填空题】
embarrass,polish, emotional, etticiency,curb ,await, donation ,dump,stuff ,historical He was [ ]when he discovered that he didn't have enough money to pay for the red wine he had ordered
【填空题】
embarrass,polish, emotional, etticiency,curb ,await, donation ,dump,stuff ,historical The local government is pressed to find new places to [ ] dump waste
【填空题】
embarrass,polish, emotional, etticiency,curb ,await, donation ,dump,stuff ,historical The new system designed to [ ] harmful emissions排放物) from factories will be put into use soon
【填空题】
explore ,transmit, resource, emerge,yield, pose, assume, confidence,inherit, comprehensive It is so difficult to [ ] the bottom of the ocean because some parts are very deep.
【填空题】
explore ,transmit, resource, emerge,yield, pose, assume, confidence,inherit, comprehensive It was about 30 seconds before Alex [ ] from the water, we were quite scared
【填空题】
explore ,transmit, resource, emerge,yield, pose, assume, confidence,inherit, comprehensive We often [ ] that when other people do the same things as we do, they do them,for the same reasons; but this assumption is not always reasonable
【填空题】
explore ,transmit, resource, emerge,yield, pose, assume, confidence,inherit, comprehensive There is widespread concern that the rising unemployment may [ ] a threat to social stability.
【填空题】
explore ,transmit, resource, emerge,yield, pose, assume, confidence,inherit, comprehensive After a(n) [ ] physical exam, my doctor said I was in good condition except that my blood pressure was a little high
【填空题】
explore ,transmit, resource, emerge,yield, pose, assume, confidence,inherit, comprehensive 7 It is well known that China is a country with rich natural [ ] and a very big population.
【填空题】
explore ,transmit, resource, emerge,yield, pose, assume, confidence,inherit, comprehensive Some people believe that the earth can [ ] enough food to support at least twice its present population
【填空题】
explore ,transmit, resource, emerge,yield, pose, assume, confidence,inherit, comprehensive Sam [ ] the gift of imagination from his family, but he lacked the driving power to take action
【填空题】
explore ,transmit, resource, emerge,yield, pose, assume, confidence,inherit, comprehensive A bee that has found honey is able to [ ] to other bees the information they need in order to collect the honey
【单选题】
在___时间内电流所做的功叫做电功率。P8T40
A. 规定
B. 标称
C. 单位
【单选题】
对单匝线圈来说,其产生的磁通与流过线圈电流的比值叫该线圈的___,也叫电感,用L表示。P11T54
A. 自感系数
B. 磁通
C. 电流
【单选题】
电器的触头系统属于电器的___P15T82。
A. 感测机械
B. 执行机构
C. 保护机械
【单选题】
触头按工作性质分为静触头和___。P16T83
A. 主触头
B. 辅助触头
C. 动触头
【单选题】
直流发电机励磁绕组与电枢绕组不相连,励磁电流由另一个独立电源供电,这样的发电机为___。P18T93
A. 并励发电机
B. 他励发电机
C. 串励发电机
欢迎使用我爱刷题
×
微信搜索我爱刷题小程序
温馨提示
×
请在电脑上登陆“www.woaishuati.com”使用