【单选题】
可编程控制器输入接口常接的部件有( )
A. 开关量信号
B. 继电器线圈
C. 电动机
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答案
A
解析
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【单选题】
可编程控制器输出接口常接的部件有( )
A. 开关量信号
B. 继电器线圈
C. 电动机
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可编程控制器小型机的I/O点数是( )
A. 64点一下
B. 64~256
C. 256~2048
【单选题】
可编程控制系统同继电器控制系统的主要区别在于( )
A. 输入部分
B. 控制部分
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下面的文字符号( )是PLC的输入继电器。
A. --I0.0
B. --C3
C. --M0.3
【单选题】
使用指针式万用在选择量限时,应使测量的指示值在仪表量限的___。
A. 初始段
B. 中间段
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【单选题】
指针式万用表测量前,指针正常应停留在___的位置。
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B. 任意位置
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当数字式万用表量程小于所测参数值时,万用表将显示___
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用数字式万用表测量直流电压时,当万用表红表笔与电源负极相接时万用表显示___
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测电阻时,不要用手触及元件裸露两端以免___。
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兆欧表测量两线柱短接时,摇动手柄到额定转速,这时表针应指在___
A. 任意位置
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用来测量交流电流的钳形电流表是由___和电流表组成的。
A. 电流互感器
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测量车间低压动力电源电流时常使用___
A. 兆欧表
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一般钳形电流表,不适用___电流的测量。
A. 单相交流电路
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三相电源的引入线标号分别是___
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三相电动机的三根引出线标号分别是___
A. --A、B、C
B. --U、V、W
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【单选题】
电气控制电路设计应最大限度地满足___的要求。
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机床上的低压照明灯,其电压不应超过___.
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在容器内工作时,照明电压应选用___伏.
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工作人员工作中正常活动范围与35KV带电设备的安全距离要大于___m。
A. 0.35
B. 0.6
C. 1。
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当某一电力线路发生接地,距接地点愈近,跨步电压___.
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1kV及以下架空线路通过居民区时,导线与地面的距离在导线最大弛度时应不小于___.
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为了降低因绝缘损坏而造成触电事故的危害,将电气设备的金属外壳和接地装置作可靠的电气连接,叫___接地。
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中性点不接地,而设备外壳接地的形式叫___。
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保护接地指的是电网的中性点不接地设备外壳___。
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在变压器中性点接地系统中,电气设备严禁采用___。
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C. 都不对。
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保护接地线用___色线。
A. 淡蓝;
B. 黄绿;
C. 浅绿。
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在三相四线制的供电系统中,常将中性线连同变压器外壳直接接地,这种接线方式称为___
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把电气设备的金属外壳及与外壳相连的金属构架与中性点接地的电力系统的零线连接起来,以保护人身安全的保护方式,叫___。
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保护接零是指低压电网电源的中性点接地,设备外壳___
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保护接零适用于___运行方式。
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工作零线用___作安全色。
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10KV/0.4KV电力变压器低压侧中性点应进行工作接地,其接地电阻值应不大于___。
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电气设备保护接地电阻越大,发生故障时漏电设备外壳对地电压___.
A. ,越低
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电器设备未经验电,一律视为___
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人体___是最危险的触电形式。
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发生电气火灾后必须进行带电灭火时,应该使用___.
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电压等级低于___伏的电器属于低压电器。
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