G电动机的选择 4教学目松 tThe choice of motor 4电动机的发热与温升 4动机的额定功减 4电动机的额定功率的选择 必有风大孚
⑦电动机的选择 教学目标 了解电动机容量选择的基本理论 掌握电力拖动系统中电动机容量选择的工程方 法 必有风大孚
The choice of motor There are many factors which must be considered when choosing a motor for a particular drive. In the following notes, the main points are highlighted but the final choice is usually a matter for the specialist. Not all the factors can be dealt with here, but the summary notes, together with the relevant sections of the main text, will be sufficient to give a good appreciation ofthe general problem. 有风族大学
The solution of this problem is not usually unique and opinions may differ widely in some cases as to he most suitable motor-drive systel However, it may be said in brief that the correct motor is the one which meets the required specification at minimum cost, but this is not a simple matter to estimate. It must include not only the capital cost of the motor-drive system itself but also the running costs. The capital cost includes the provision ofany special supplies find control gear to run the motor 有风族大学
The running cost includes interest, charges on capital equipment and buildings and charges for the power losses consumed in the machine and control circuits; obviously power factor and efficiency are of significance here. Maintenance is also a regular running cost and would normally be higher with complex control gear and with machines having rubbing contacts at slip rings and commentators Installation costs too may be decisive; for example, special foundations are required for motor-generator sets but not for static conversion equipment Such equipment also makes less demands on space and is less noisy than rotating machinery On the other hand, there is considerable harmonic generation which poses a suppression problem 必有风大孚