電機軸低頻軸電流的預防措施

　一(yi)般來說, 防止低頻軸(zhou)電(dian)流(liu)產(chan)生(sheng)的常規(gui)措施有(you)如下幾種: (1) 增(zeng)加接(jie)(jie)地碳刷, 使轉(zhuan)軸(zhou)接(jie)(jie)地; (2) 使用絕緣(yuan)(yuan)軸(zhou)承; (3) 使用對(dui)稱電(dian)纜(lan); (4) 增(zeng)加補償變壓器(qi); (5) 增(zeng)加絕緣(yuan)(yuan)板。 高頻軸(zhou)電(dian)流(liu)的預防措施

　　(1) 選擇正確的電纜

　　必須選(xuan)用對稱(cheng)的(de)多芯電纜，電纜的(de)接地線(xian)(PE，保護接地)必須對稱(cheng)排列; 電纜的(de)屏(ping)(ping)蔽(bi)(bi)層選(xuan)用銅(tong)編制帶(dai)，因(yin)為銅(tong)的(de)導電性(xing)能(neng)優越(yue)，屏(ping)(ping)蔽(bi)(bi)效果比(bi)較好; 屏(ping)(ping)蔽(bi)(bi)層的(de)總截面積(ji)應(ying)不小(xiao)于相線(xian)的(de)1/2;

　　電纜頭兩端(duan)做360°的接頭，并分別與(yu)變頻(pin)柜和(he)電機內接地端(duan)連(lian)接。

　　(2) 安(an)裝高頻(pin)濾波(bo)器

　　只要變頻器(qi)處的高(gao)頻諧波(bo)(bo)存在，就會產(chan)生共模(mo)電流(liu)(liu)(liu)，所以(yi)如果(guo)能夠對高(gao)頻電流(liu)(liu)(liu)進行衰減(jian)，則可以(yi)在源(yuan)頭上抑(yi)制軸電流(liu)(liu)(liu)。在變頻器(qi)的輸出線上安(an)裝(zhuang)共模(mo)濾波(bo)(bo)器(qi)，具體(ti)措施為:在三相對稱電纜的外面套上濾波(bo)(bo)器(qi)磁(ci)環，使高(gao)頻電流(liu)(liu)(liu)在磁(ci)環中(zhong)被吸(xi)收。由于高(gao)頻電流(liu)(liu)(liu)會產(chan)生高(gao)頻磁(ci)場，所以(yi)濾波(bo)(bo)器(qi)可以(yi)做成非接觸(chu)式。

　　開關電源濾(lv)波(bo)器中的電容一般要求電感值比較小，這樣諧(xie)振(zhen)頻率高(gao)(gao)，抑制高(gao)(gao)頻電流(liu)的效果好。某線材廠主電機的變頻柜內已經安裝了共模濾(lv)波(bo)器，與安裝前(qian)相比，在電機側(ce)的高(gao)(gao)頻電流(liu)值明顯有所下(xia)降。 (3) 均衡(heng)接地電壓(ya)

　　由于存在(zai)(zai)雜(za)散(san)電(dian)(dian)(dian)(dian)容，在(zai)(zai)同一根(gen)電(dian)(dian)(dian)(dian)纜的(de)(de)屏蔽(bi)層(都已接(jie)(jie)(jie)(jie)地(di)(di)(di))上(shang)兩端(逆變(bian)(bian)器(qi)側(ce)與(yu)(yu)電(dian)(dian)(dian)(dian)機(ji)側(ce))的(de)(de)地(di)(di)(di)電(dian)(dian)(dian)(dian)壓(ya)(ya)實際上(shang)并非(fei)完全一致，這樣在(zai)(zai)電(dian)(dian)(dian)(dian)纜上(shang)存在(zai)(zai)壓(ya)(ya)降(jiang)(jiang)，就(jiu)會存在(zai)(zai)電(dian)(dian)(dian)(dian)流(liu)(liu)。所以，可以考慮均衡接(jie)(jie)(jie)(jie)地(di)(di)(di)電(dian)(dian)(dian)(dian)壓(ya)(ya)，降(jiang)(jiang)低電(dian)(dian)(dian)(dian)纜屏蔽(bi)層上(shang)的(de)(de)壓(ya)(ya)降(jiang)(jiang)，從而(er)降(jiang)(jiang)低軸(zhou)電(dian)(dian)(dian)(dian)流(liu)(liu)。具(ju)體做法是在(zai)(zai)現場(chang)安裝一個(ge)共用(yong)接(jie)(jie)(jie)(jie)地(di)(di)(di)母排，然(ran)后(hou)將各電(dian)(dian)(dian)(dian)機(ji)接(jie)(jie)(jie)(jie)地(di)(di)(di)端子與(yu)(yu)之(zhi)相連接(jie)(jie)(jie)(jie)。由于變(bian)(bian)頻柜內的(de)(de)接(jie)(jie)(jie)(jie)地(di)(di)(di)線是引自系統總(zong)的(de)(de)接(jie)(jie)(jie)(jie)地(di)(di)(di)裝置，從而(er)將電(dian)(dian)(dian)(dian)機(ji)與(yu)(yu)逆變(bian)(bian)器(qi)的(de)(de)接(jie)(jie)(jie)(jie)地(di)(di)(di)電(dian)(dian)(dian)(dian)壓(ya)(ya)均衡，降(jiang)(jiang)低電(dian)(dian)(dian)(dian)壓(ya)(ya)降(jiang)(jiang)。另外，可以考慮降(jiang)(jiang)低電(dian)(dian)(dian)(dian)機(ji)電(dian)(dian)(dian)(dian)纜屏蔽(bi)線的(de)(de)接(jie)(jie)(jie)(jie)地(di)(di)(di)電(dian)(dian)(dian)(dian)阻(zu)，使該電(dian)(dian)(dian)(dian)纜上(shang)部分電(dian)(dian)(dian)(dian)流(liu)(liu)在(zai)(zai)通過電(dian)(dian)(dian)(dian)機(ji)軸(zhou)承(cheng)之(zhi)前直接(jie)(jie)(jie)(jie)接(jie)(jie)(jie)(jie)地(di)(di)(di)，分流(liu)(liu)流(liu)(liu)經(jing)軸(zhou)承(cheng)的(de)(de)電(dian)(dian)(dian)(dian)流(liu)(liu)。