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《《电机与变压器》期末试卷.doc》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、密封线※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※
2、※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※班级姓名学号XX市XX学校2013年1月XX级《电机与变压器》期末试卷
3、题号一二三四五六总分得分一.填空题:(每空1分共25分)1.变压器按用途分互感器、变压器、变压器和变压器。2.三相异步电动机定子是用来产生磁场的,一般由、和定子绕组等部分组成。3.三相绕线式转子异步电动机有转子串及转子串接变阻器两种启动方法。4.异步电动机的电气制动分为制动、制动和制动。5.无刷直流电动机由、位置传感器和开关线路三部分组成。6.伺服电动机又称电动机,它具有服从信号的要求而动作的职能。7.测速发电机可以分为测速发电机和测速发电机两大类。8.同步电动机启动方法有辅助启动法、启动法、启动法。9.自励发电机按励磁绕组的接线不同可分为励、励和励三种。二.判断题(10
4、分)1.电流互感器二次侧近似如短路状态。()2.三相异步电动机的转向取决于旋转磁场方向。()3.罩极式电动机启动性能和运行性能都较好。()4.直流电动机的主要缺点是换向问题。()5.电驱反应对直流电动机是有利的。()6.超声波电动机是非电磁性电动机。()7.直线电动机多用于各种定位系统和自动控制系统。()8.直流电动机改变励磁电流大小调速转速只能往上调。()9.小功率三相电动机可改为单相电动机运行。()10.变频调速优点是质量轻、体积小、惯性小、效率高。()三.术语解释:(共15分)1.磁动势:2.转差率:3.YR160S2WF:4.步进电动机:5.正弦绕组:四.简答题:
5、(10分+10分)1.简述电焊变压器应满足弧焊过程中的工艺要求。2.简述异步电动机直接启动的条件。五.电路分析与计算(15分)1.某晶体管收音机的输出变压器一次侧匝数N1=230匝;二次侧匝数N2=50匝,原来配接阻抗为8Ω的扬声器,现要改用同样功率二阻抗为4Ω的扬声器,则二次侧匝数N2应改为多少?六.电路计算与绘图(15分)1.某电容启动单相异步电动机定子槽数为24槽,极数为4极,画出同心绕组的展开图。密封线※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※
6、※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※
7、※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※※
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