问题 问答题 简答题

目前汽轮发电机励磁方式有哪几种?

答案

参考答案:

目前我国常用的励磁方式如下:

(1)100MW及以下的发电机,基本上采用同轴直流励磁机。

(2)100MW以上大容量发电机采用半导体励磁,其形式有以下三种:

A.同轴交流发电机式静止半导体励磁。由交流发电机发出交流电,经过静止的半导体整流后变成直流,供给发电机励磁;

B.他励式静止半导体励磁。由发电机发出的交流电,经过变压器降压后由静止半导体整流变成直流电,供给发电机励磁。发电机升压前,励磁交流电源由厂用电供给,当升到额定电压的30%自动切换成发电机本身供给;

C.旋转式半导体励磁。由同轴中频发电机(副励磁机)、电枢旋转的交流励磁机和装在发电机大轴内的半导体整流装置构成。

材料分析题

材料:2009年12月7日起,192个国家的环境部长和其他官员们在丹麦首都哥本哈根召开联合国气候会议,商讨《京都议定书》一期承诺到期后的后续方案,就未来应对气候变化的全球行动签署新的协议。这是继《京都议定书》后又一具有划时代意义的全球气候协议书,毫无疑问,对地球今后的气候变化走向产生决定性的影响。这是一次被喻为“拯救人类的最后一次机会”的会议。

(1)结合所学的相关知识谈谈你从下图漫画《许愿》中得到的体会。

                                                                                                                                                               

                                                                                                                                                               

                                                                                                                                                               

                                                                                                                                                               

                                                                                                                                                               

                                                                                                                                                              

(2)为了实现地球的这一愿望,我们必须坚持实施什么样的国策和贯彻什么样的发展战略?

                                                                                                                                                               

(3)你准备为实现地球的这一愿望做些什么?

                                                                                                                                                              

                                                                                                                                                              

                                                                                                                                                             

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