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Products一、發電機(ji)轉子交流(liu)阻(zu)抗測(ce)試儀測(ce)試方法實例(li)
實(shi)例1-1 用交流耐(nai)壓判定(ding)接地故障點(dian)
某電(dian)(dian)廠一臺200MW發電(dian)(dian)機(水(shui)氫(qing)(qing)氫(qing)(qing)冷卻方(fang)式(shi))其(qi)勵磁電(dian)(dian)壓(ya)為455V,由及(ji)絕(jue)緣電(dian)(dian)阻及(ji)損耗試驗(yan)(yan)得判定該機轉(zhuan)(zhuan)子(zi)繞組接(jie)地(di)(di)點在(zai)負(fu)極(ji)側,接(jie)地(di)(di)性(xing)質為動態高阻抗(kang)接(jie)地(di)(di),但未(wei)發現(xian)有(you)匝間短路(lu)。在(zai)對轉(zhuan)(zhuan)子(zi)繞組做交流(liu)耐(nai)壓(ya)試驗(yan)(yan)時,當試驗(yan)(yan)電(dian)(dian)壓(ya)加至1800V時,發現(xian)負(fu)極(ji)滑環側有(you)放(fang)電(dian)(dian)聲,同時有(you)煙霧。用GD2570絕(jue)緣電(dian)(dian)阻測試儀測絕(jue)緣電(dian)(dian)阻為10MΩ,判斷接(jie)地(di)(di)點在(zai)轉(zhuan)(zhuan)子(zi)負(fu)極(ji)滑環引線及(ji)導電(dian)(dian)螺釘處,解體檢查發現(xian)導屯螺釘緊力不夠,其(qi)硅橡膠密封套已過熱(re)變形,結合面已碳化,有(you)明顯(xian)的(de)放(fang)電(dian)(dian)痕跡。導電(dian)(dian)螺釘經金屬(shu)墊圈與(yu)大軸構成接(jie)地(di)(di)點,從(cong)而造成高阻接(jie)地(di)(di)。
(1)測試(shi)方法和《發(fa)電機定子繞組的交流耐壓試(shi)驗(yan)方法》相似(si)。
(2)對于(yu)水(shui)(shui)內冷轉(zhuan)子(zi)應在通水(shui)(shui)情況下進行試驗。
(3)由于一般(ban)勵磁(ci)電(dian)(dian)壓(ya)都較低(di),故試驗電(dian)(dian)壓(ya)也較低(di),例(li)如:300MW發(fa)電(dian)(dian)機(GDU-300-2)的勵磁(ci)電(dian)(dian)壓(ya)為(wei)365V,對隱極(ji)式轉子為(wei)5UN,即5×365V=1825V。故用(yong)一般(ban)的試驗變壓(ya)器就可以了。當然(ran),試驗前后的充(chong)分放電(dian)(dian)還是必要(yao)的。
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。