直流電動機起動

    直流電動機起動

    由you於yu電dian機ji電dian樞shu回hui路lu電dian阻zu和he電dian感gan都dou較jiao小xiao


，而er轉zhuan動dong體ti具ju有you一yi定ding的de機ji械xie慣guan性xing
，因yin此ci當dang電dian機ji接jie通tong電dian源yuan後hou
，起qi動dong的de開kai始shi階jie段duan電dian樞shu轉zhuan速su以yi及ji相xiang應ying的de反fan電dian動dong勢shi很hen小xiao，起qi動dong電dian流liu很hen大da。最zui大da可ke達da額e定ding電dian流liu的de15～20倍。這一電流會使電網受到擾動、機組受到機械衝擊、換向器發生火花。因此直接合閘起動隻適用於功率不大於4千瓦的電動機（起動電流為額定電流的6～8倍）。
    為了限製起動電流，常在電樞回路內串入專門設計的可變電阻,其原理接線見圖1。zaiqidongguochengzhongsuizhezhuansudebuduanshenggaojishizhujijianggefenduandianzuduanjie
，shiqidongdianliuxianzhizaimouyiyunxuzhiyinei。zhezhongqidongfangfachengweichuandianzuqidong，feichangjiandan，shebeiqingbian，guangfanyingyongyugezhongzhongxiaoxingzhiliudiandongjizhong。danyouyuqidongguochengzhongnengliangxiaohaoda，bushiyujingchangqidongdedianjihezhong、大da型xing直zhi流liu電dian動dong機ji。但dan對dui於yu某mou些xie特te殊shu需xu要yao，例li如ru城cheng市shi電dian車che雖sui經jing常chang起qi動dong，為wei了le簡jian化hua設she備bei，減jian輕qing重zhong量liang和he操cao作zuo維wei修xiu方fang便bian
，通tong常chang采cai用yong串chuan電dian阻zu起qi動dong方fang法fa。

    duirongliangjiaodadezhiliudiandongji
，tongchangcaiyongjiangdianyaqidong。jiyoudandudeketiaoyazhiliudianyuanduidianjidianshugongdian
，kongzhidianyuandianyajikeshidianjipinghuaqidong，younengshixiantiaosu。cizhongfangfadianyuanshebeibijiaofuza。