一、發電機轉子(zi)交流阻抗測試儀(yi)測試方法實例(li)
實例1-1 用交流耐壓(ya)判定(ding)接地(di)故障點
某電(dian)(dian)(dian)(dian)(dian)廠一臺200MW發電(dian)(dian)(dian)(dian)(dian)機（水(shui)氫(qing)氫(qing)冷卻方式）其勵磁電(dian)(dian)(dian)(dian)(dian)壓為(wei)455V，由及絕緣(yuan)電(dian)(dian)(dian)(dian)(dian)阻及損(sun)耗(hao)試(shi)驗(yan)得判定該機轉子(zi)繞組接地點(dian)在(zai)負極側，接地性質為(wei)動態(tai)高阻抗接地，但未發現(xian)有(you)匝間短路(lu)。在(zai)對轉子(zi)繞組做交流耐壓試(shi)驗(yan)時(shi)，當試(shi)驗(yan)電(dian)(dian)(dian)(dian)(dian)壓加至1800V時(shi)，發現(xian)負極滑(hua)環(huan)側有(you)放電(dian)(dian)(dian)(dian)(dian)聲，同時(shi)有(you)煙(yan)霧。用GD2570絕緣(yuan)電(dian)(dian)(dian)(dian)(dian)阻測(ce)試(shi)儀測(ce)絕緣(yuan)電(dian)(dian)(dian)(dian)(dian)阻為(wei)10MΩ，判斷(duan)接地點(dian)在(zai)轉子(zi)負極滑(hua)環(huan)引線及導電(dian)(dian)(dian)(dian)(dian)螺(luo)釘(ding)處，解體(ti)檢查發現(xian)導屯螺(luo)釘(ding)緊力不夠，其硅橡膠密封套已過熱變形，結合面(mian)已碳化，有(you)明顯(xian)的放電(dian)(dian)(dian)(dian)(dian)痕跡(ji)。導電(dian)(dian)(dian)(dian)(dian)螺(luo)釘(ding)經金屬(shu)墊圈與大(da)軸(zhou)構成接地點(dian)，從而造成高阻接地。
(1)測試方(fang)法和《發電機定子(zi)繞組的交流耐壓(ya)試驗(yan)方(fang)法》相似。
(2)對于水內冷轉子應在通水情況下進(jin)行試驗。
(3)由于一般勵磁(ci)電壓(ya)都較(jiao)低，故(gu)試驗電壓(ya)也較(jiao)低，例(li)如：300MW發電機(ji)（GDU-300-2）的(de)勵磁(ci)電壓(ya)為365V，對隱極式轉子為5UN，即5×365V＝1825V。故(gu)用一般的(de)試驗變壓(ya)器就可以了。當然，試驗前后的(de)充(chong)分放(fang)電還是必要的(de)。
對隱極式轉子一般情況下不做交流耐壓，但在尋找接地故障點時，也可用來判斷接地點的位置。
