英文加翻译.docVIP

沈阳工业大学 本科生毕业设计（论文）外文翻译 外文题目： Electrical Machine Control Systems 学 院： 沈阳工业大学工程学院 专业班级： 电气工程及其自动化0303 学生姓名： 王 晶 晶 指导教师： 皮 红 梅 （副教授） 2007年 3 月 19日 Electrical Machine Control Systems Control Symbols It is necessary to become familiar with the electrical symbols which are commonly used with machine control systems . Machine Control with Switches An important type of electrical machine control is the switch . Many types of switches are used to control electrical machine .The function of a switch is to turn a circuit on or off ; however , many more complex switch functions can be performed Toggle switches Among the simplest type of switches are toggle switches . Notice the symbols that are used for various types of toggle switches. Pushbutton switches Pushbutton switches are commonly used for machine control .Many machine control applications use pushbuttons as a means of starting , stopping ,or reversing a motor .Pushbuttons are manually operated to close or open a machine control circuit .There are types of pushbuttons used for the control of machine .Pushbuttons are usually mounted in enclosures called motor control stations. Ordinarily ,pushbuttons are either the normally closed(NC)or normally open(NO)types . However ,there air a few modifications . A normally closed pushbutton is closed until it is depressed manually and will open a circuit it is depressed manually and will open until it is manually depressed and then ,once it is depressed ,it will close a circuit. The “ stop ”switches of NC type. (3).Rotary switches Another common type of switch. Many different switching combinations can be wired by using a rotary switch .The shaft of a rotary switch is attached to sets of moving contacts .These moving contacts touch different sets of stationary contacts which are mounted on ceramic segments when the rotary shaft is turned to different positions .The shaft can lock into place in any of