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【单选题】
一般线路中的熔断器有( )保护。 ___
A. 过载
B. 短路
C. 过载和短路
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答案
C
解析
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某四极电动机的转速为 1440r/min,则这台电动机的转差率为( )%。 ___
A. 4
B. 2
C. 6
【单选题】
指针式万用表一般可以测量交直流电压、( )电流和电阻。 ___
A. 交流
B. 交直流
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尖嘴钳 150mm 是指( )。 ___
A. 其总长度为 150mm
B. 其绝缘手柄为 150mm
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继电器是一种根据( )来控制电路“接通”或“断开”的一种自动电器。 ___
A. 电信号
B. 外界输入信号(电信号或非电信号)
C. 非电信号
【单选题】
导线接头连接不紧密,会造成接头( )。 ___
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低压线路中的零线采用的颜色是( )。 ___
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【单选题】
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【单选题】
电压继电器使用时其吸引线圈直接或通过电压互感器( )在被控电路中。 ___
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【单选题】
熔断器在电动机的电路中起( )保护作用。 ___
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【单选题】
电动机定子三相绕组与交流电源的连接叫接法,其中 Y 为( )。 ___
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在选择漏电保护装置的灵敏度时,要避免由于正常( )引起的不必要的动作而影响正 常供电。
A. 泄漏电压
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【单选题】
万能转换开关的基本结构内有( )。 ___
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【单选题】
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【单选题】
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【判断题】
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