【单选题】
绕组对油箱的绝缘属于变压器的___。
A. 外绝缘;
B. 主绝缘;
C. 纵绝缘;
D. 次绝缘。
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答案
B
解析
暂无解析
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【单选题】
油浸电力变压器的呼吸器硅胶的潮解不应超过___。
A. 1/2;
B. 1/3;
C. 1/4;
D. 1/5。
【单选题】
变压器中性点接地叫___。
A. 工作接地;
B. 保护接地;
C. 工作接零;
D. 保护接零。
【单选题】
变压器二次侧突然短路时,短路电流大约是额定电流的___倍。
A. 1~3;
B. 4~6;
C. 6~7;
D. 10~25。
【单选题】
绕组中的感应电动势大小与绕组中的___。
A. 磁通的大小成正比;
B. 磁通的大小成反比;
C. 磁通的大小无关,而与磁通的变化率成正比;D、磁通的变化率成反比。
【单选题】
油浸变压器温度计所反映的温度是变压器的___。
A. 上部温度;
B. 中部温度;
C. 下部温度;
D. 匝间温度。
【单选题】
变压器的使用年限主要决定于___的运行温度。
A. 绕组;
B. 铁芯;
C. 变压器油;
D. 外壳。
【单选题】
变压器低压线圈比高压线圈的导线直径___。
A. 粗;
B. 细;
C. 相等;
D. 粗、细都有。
【单选题】
同电源的交流电动机,极对数多的电动机其转速___。
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B. 高;
C. 不变;
D. 不一定。
【单选题】
当一台电动机轴上的负载增加时,其定子电流___。
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B. 增加;
C. 减小;
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【单选题】
异步电动机是一种___的设备
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【单选题】
异步电动机的转矩与___。
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感应电动机的转速,永远___旋转磁场的转速。
A. 大于;
B. 小于;
C. 等于;
D. 不变。
【单选题】
规定为星形接线的电动机,而错接成三角形,投入运行后___急剧增大。
A. 空载电流;
B. 负荷电流;
C. 三相不平衡电流;
D. 零序电流。
【单选题】
规定为三角形接线的电动机,而误接成星形,投入运行后___急剧增加。
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【单选题】
异步电动机的三相绕组加上三相对称电压后,在转子尚未转动的瞬间,转子上的电磁转矩___。
A. 最大;
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D. 等于1。
【单选题】
异步电动机在启动过程中,使电动机转子转动并能达到额定转速的条件是___。
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【单选题】
电动机运行电压在额定电压的___范围内变化时其额定出力不变。
A. -10%~+5%;
B. -5%~+10%;
C. -10%~+10%;
D. -10%~+15%。
【单选题】
如果一台三相交流异步电动机的转速为2820rpm,则其转差率S是___。
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电动机连续额定工作方式,是指该电动机长时间带额定负载运行而其___不超过允许值。
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【单选题】
电动机定子旋转磁场的转速和转子转速的差数,叫做___。
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D. 滑差率。
【单选题】
当电动机的外加电压降低时,电动机的转差率将___。
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当电动机所带的机械负载增加时,电动机的转差将___。
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【单选题】
感应电动机的额定功率___从电源吸收的总功率。
A. 大于;
B. 小于;
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D. 变化的。
【单选题】
电动机铭牌上的“温升”指的是___的允许温升。
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异步电动机在起动时的定子电流约为额定电流的___。
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【单选题】
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下列保护系统中___具有高可靠性、灵活性和功能强大的特点。
A. 分散表计;
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C. 微机型保护测量控制系统;D、晶体管型保护系统。
【单选题】
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【单选题】
变压器出现___情况时,应立即停止变压器运行。
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【单选题】
热继电器是利用双金属受热的___来保护电气设备的。
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【单选题】
对于电气设备而言,所谓接地电阻是指___。
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【单选题】
为了保障人身安全,将电气设备正常情况下不带电的金属外壳接地称为___。
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A. 90;
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【单选题】
氢气热容量大,导热性能比空气高___。
A. 五倍;
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【单选题】
测量仪表的准确度等级若是0.5级,则该仪表的基本误差是___。
A. +0.5%;
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C. ±0.5%;
D. ±0.25%。
【单选题】
兆欧表是测量绝缘电阻和___的专用仪表。
A. 吸收比;
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