電(dian)力電(dian)纜(lan)的常見故(gu)障 電(dian)纜(lan)故(gu)障處理技巧(qiao)
接地(di)或短路故(gu)障(zhang)、斷線故(gu)障(zhang)、斷線并(bing)接地(di)故(gu)障(zhang)和閃絡性故(gu)障(zhang)等(deng)。
故障的判斷方法
確定(ding)電纜故障類型(xing)的(de)方(fang)法是用絕緣電阻(zu)表在(zai)線(xian)路一端測(ce)量各相的(de)絕緣電阻(zu)。一般根據以下(xia)情況確定(ding)故障類型(xing):
(1)當搖測電纜一芯(xin)(xin)或(huo)幾芯(xin)(xin)對地絕緣(yuan)(yuan)電阻(zu),或(huo)芯(xin)(xin)與芯(xin)(xin)之間絕緣(yuan)(yuan)電阻(zu)低于100千歐時,為低電阻(zu)接(jie)地或(huo)短路故(gu)障。
(2)當(dang)搖測電(dian)(dian)纜(lan)一芯或(huo)幾芯對地(di)絕緣電(dian)(dian)阻,或(huo)芯與芯之間絕緣電(dian)(dian)阻低于正常值很多,但高于100千歐時,為高電(dian)(dian)阻接地(di)故障(zhang)。
(3)當搖測(ce)電纜一芯(xin)或(huo)幾(ji)芯(xin)對地(di)絕緣電阻較高或(huo)正常,應(ying)進行導體連續性試驗,檢查是否有斷(duan)線(xian),若有即為斷(duan)線(xian)故障。
(4)當(dang)搖測電纜有(you)一芯或幾芯導(dao)體不連續,且經電阻接地時,為斷線并(bing)接地故(gu)障(zhang)。
(5)閃(shan)絡(luo)性(xing)故(gu)障多(duo)發(fa)生(sheng)(sheng)于預防性(xing)耐壓(ya)試驗,發(fa)生(sheng)(sheng)部位大多(duo)在電纜終端(duan)和中(zhong)間(jian)接頭。閃(shan)絡(luo)有時(shi)會連續(xu)多(duo)次(ci)發(fa)生(sheng)(sheng),每次(ci)間(jian)隔幾(ji)秒(miao)至幾(ji)分鐘。
故障的測試方法
過(guo)去使(shi)用(yong)的儀器設備有QF1-A型電(dian)纜探測儀、DLG-1型閃(shan)測儀,電(dian)纜路徑(jing)儀及故(gu)(gu)(gu)障(zhang)定點(dian)儀等(deng)。目前(qian)最為流(liu)行的測試方法是閃(shan)測法,它(ta)包括沖(chong)(chong)閃(shan)和直閃(shan),最常用(yong)的是沖(chong)(chong)閃(shan)法。沖(chong)(chong)閃(shan)測試精度較(jiao)高(gao)(gao),操作(zuo)簡單,安全可靠。其設備主要(yao)由兩(liang)部分組成,即高(gao)(gao)壓(ya)(ya)(ya)發生裝(zhuang)置(zhi)和電(dian)流(liu)脈(mo)沖(chong)(chong)儀。高(gao)(gao)壓(ya)(ya)(ya)發生裝(zhuang)置(zhi)是用(yong)來(lai)產(chan)生直流(liu)高(gao)(gao)壓(ya)(ya)(ya)或沖(chong)(chong)擊高(gao)(gao)壓(ya)(ya)(ya),施加于故(gu)(gu)(gu)障(zhang)電(dian)纜上,迫使(shi)故(gu)(gu)(gu)障(zhang)點(dian)放(fang)電(dian)而(er)產(chan)生反射(she)信(xin)號。電(dian)流(liu)脈(mo)沖(chong)(chong)儀是用(yong)來(lai)拾取(qu)反射(she)信(xin)號測量(liang)故(gu)(gu)(gu)障(zhang)距離或直接(jie)用(yong)低壓(ya)(ya)(ya)脈(mo)沖(chong)(chong)測量(liang)開路、短路或低阻故(gu)(gu)(gu)障(zhang)。下(xia)面以故(gu)(gu)(gu)障(zhang)點(dian)電(dian)阻為依據簡述一下(xia)測試方法:
(1)當故(gu)(gu)障(zhang)點電(dian)阻(zu)等于無窮大時(shi),用(yong)低壓脈沖法測量(liang)容易找(zhao)到斷(duan)(duan)路故(gu)(gu)障(zhang),一(yi)般來說,純粹性斷(duan)(duan)路故(gu)(gu)障(zhang)不常見到,通常斷(duan)(duan)路故(gu)(gu)障(zhang)為(wei)相對地(di)或相間高阻(zu)故(gu)(gu)障(zhang),及相對地(di)或相間低阻(zu)故(gu)(gu)障(zhang)并存。
(2)當故(gu)障點電阻等于零時,用低(di)壓脈沖(chong)法測量短路故(gu)障容(rong)易找到,但實際工作中遇到這種(zhong)故(gu)障很(hen)少。
(3)當故障(zhang)點電阻大于(yu)零(ling)小于(yu)100千(qian)歐(ou)時,用低(di)壓脈沖法測量容易找(zhao)到低(di)阻故障(zhang)。
(4)閃絡故障可用直閃法(fa)測量,這種故障一般存在于接頭內部,故障點電阻大(da)于100千歐,但(dan)數值變化較(jiao)大(da),每次(ci)測量不確定。
(5)高阻故障(zhang)可用沖(chong)閃法測(ce)量(liang),故障(zhang)點(dian)(dian)電(dian)(dian)阻大于100千(qian)歐且數值確定。一般當(dang)測(ce)試(shi)電(dian)(dian)流大于15毫安,測(ce)試(shi)波形具有重(zhong)復性以(yi)及可以(yi)相重(zhong)疊,同時一個波形有一個發射、三個反射且脈沖(chong)幅度逐漸減弱時,所測(ce)的距(ju)離為(wei)故障(zhang)點(dian)(dian)到電(dian)(dian)纜(lan)測(ce)試(shi)端的距(ju)離;否則為(wei)故障(zhang)點(dian)(dian)到電(dian)(dian)纜(lan)測(ce)試(shi)對端的距(ju)離。
電纜(lan)(lan)故(gu)(gu)障(zhang)(zhang)測(ce)試技(ji)術(shu)水平的(de)(de)(de)提高,應針對不(bu)同(tong)的(de)(de)(de)故(gu)(gu)障(zhang)(zhang)性質采取不(bu)同(tong)的(de)(de)(de)方(fang)法,還要不(bu)斷引(yin)進(jin)新技(ji)術(shu)、新設備,同(tong)時也要在新設備上摸索經驗,開發新的(de)(de)(de)功能。如現采用的(de)(de)(de)發音(yin)頻信(xin)號給電纜(lan)(lan),在故(gu)(gu)障(zhang)(zhang)點(dian)接(jie)收信(xin)號的(de)(de)(de)測(ce)試技(ji)術(shu),以(yi)(yi)及利(li)用T16/910電纜(lan)(lan)故(gu)(gu)障(zhang)(zhang)測(ce)試儀(yi)的(de)(de)(de)SDC系列(lie)高智(zhi)能電纜(lan)(lan)故(gu)(gu)障(zhang)(zhang)閃測(ce)儀(yi)對故(gu)(gu)障(zhang)(zhang)點(dian)的(de)(de)(de)精(jing)確定位(wei)。這些設備可以(yi)(yi)使其(qi)測(ce)量誤差(cha)控制在幾十厘(li)米以(yi)(yi)內,直接(jie)找到故(gu)(gu)障(zhang)(zhang)點(dian)進(jin)行處理,提高了故(gu)(gu)障(zhang)(zhang)測(ce)尋(xun)的(de)(de)(de)效(xiao)率。