bianyaqiyoudejiedianqiangduhuojichuandianyashihengliangtazaidianqishebeineibunengnaishoudianyadenenglierbubeipohuaidechidu,shijianyanbianyaqiyouxingnenghaohuaidezhuyaoshouduanzhiyi。tashijishangshiceliangjueyuanyoudeshunshijichuandianyazhi。chunjingdejueyuanyouzhongzonghuiyouyixieziyoudianzizaiwaijiedegaonengshexianzuoyongxiayoulichulai,huozaijubuqiangdianchangzuoyongxiacongyinjilengshechulai。zhexiedianzizaidianchangzuoyongxiachanshengzhuangjiyouli,zuizhonghuidaozhijueyuanyoujichuan,youyuzhezhongjichuanwanquanyoudiandezuoyongzaocheng,guchengwei“電擊穿”。工程上用的絕緣油總是不很純淨的,含有各種各樣的雜質。不純淨的絕緣油的擊穿是由於雜質形成的“小橋”貫穿電極之間,而“小橋”的電導較大,使泄露電流增大,發熱嚴重,遊離過程增強,最後導致“小橋”通道遊離擊穿。這一過程是與熱過程緊密聯係著,故稱為“熱擊穿”。
幹燥劑的油品具有相當高的擊穿電壓值,一般國產油的擊穿電壓值都在40kV以上,有的可達60kV以上。但當油品中含有遊離水、溶解水分或固形物時,由於這些雜誌都具有比油本身大的電導率和介電常數,它們在電場(電壓)作用下會構成導電橋路,而降低油的擊穿電壓值。此實驗可以判斷油中是否存在有水分、雜質和導電微粒,但它不能判斷油品是否存在有酸性物質或油泥。
影響擊穿電壓的因素:
(1)shuifen。shuifenshiyingxiangjichuandianyazuilingmindezangwu。yinweishuishiyizhongjixingfenzi,zaidianchanglizuoyongxia,henrongyibeilachang,bingyanzhedianchangfangxiangpailie,congerzailiangjijianxingchengdaodian“小橋”,使(shi)擊(ji)穿(chuan)電(dian)壓(ya)劇(ju)降(jiang)。另(ling)外(wai),擊(ji)穿(chuan)電(dian)壓(ya)的(de)大(da)小(xiao)不(bu)僅(jin)取(qu)決(jue)於(yu)含(han)水(shui)量(liang),還(hai)取(qu)決(jue)於(yu)水(shui)在(zai)油(you)中(zhong)所(suo)處(chu)的(de)狀(zhuang)態(tai),通(tong)常(chang)乳(ru)化(hua)水(shui)對(dui)擊(ji)穿(chuan)電(dian)壓(ya)影(ying)響(xiang)最(zui)大(da),溶(rong)解(jie)水(shui)次(ci)之(zhi)。
(2)youzhonghanyouweiliangdeqipao,yehuishijichuandianyadianyamingxianxiajiang,yinweiyouzhongcunzaiqipao,zezaijiaodidianyaxiaqipaobiankeyouli,bingzaidianchanglizuoyongxia,zaidianjijianxingchengdaodian“小橋”,使油被擊穿,降低了油的擊穿電壓。
(3)溫wen度du對dui擊ji穿chuan電dian壓ya的de影ying響xiang視shi油you中zhong雜za質zhi和he水shui分fen的de有you無wu而er不bu同tong。不bu含han雜za質zhi,並bing經jing幹gan燥zao無wu水shui分fen的de油you,一yi般ban溫wen度du對dui擊ji穿chuan電dian壓ya影ying響xiang不bu大da。但dan當dang溫wen度du升sheng高gao到dao一yi定ding溫wen度du時shi,油you分fen子zi本ben身shen因yin裂lie解jie而er產chan生sheng電dian離li,且qie隨sui著zhe溫wen度du的de升sheng高gao,油you品pin的de粘zhan度du顯xian著zhu減jian小xiao,電dian離li產chan生sheng的de電dian子zi和he離li子zi由you於yu阻zu力li變bian小xiao而er運yun行xing速su度du加jia快kuai,導dao致zhi油you品pin被bei擊ji穿chuan,擊ji穿chuan電dian壓ya顯xian著zhu下xia降jiang。
如(ru)果(guo)油(you)中(zhong)含(han)有(you)雜(za)質(zhi)和(he)水(shui)分(fen)時(shi),則(ze)在(zai)同(tong)一(yi)溫(wen)度(du)下(xia),其(qi)擊(ji)穿(chuan)電(dian)壓(ya)比(bi)無(wu)雜(za)質(zhi)。水(shui)分(fen)的(de)油(you)的(de)擊(ji)穿(chuan)電(dian)壓(ya)要(yao)低(di),溫(wen)度(du)較(jiao)低(di)時(shi),油(you)中(zhong)水(shui)多(duo)呈(cheng)懸(xuan)浮(fu)狀(zhuang),其(qi)擊(ji)穿(chuan)電(dian)壓(ya)值(zhi)較(jiao)小(xiao),隨(sui)著(zhe)溫(wen)度(du)的(de)升(sheng)高(gao),乳(ru)狀(zhuang)水(shui)逐(zhu)漸(jian)變(bian)為(wei)溶(rong)解(jie)狀(zhuang),油(you)品(pin)的(de)擊(ji)穿(chuan)電(dian)壓(ya)隨(sui)之(zhi)上(shang)升(sheng)。但(dan)如(ru)果(guo)溫(wen)度(du)升(sheng)高(gao)到(dao)一(yi)定(ding)程(cheng)度(du),則(ze)油(you)中(zhong)水(shui)分(fen)發(fa)生(sheng)蒸(zheng)發(fa),在(zai)油(you)中(zhong)造(zao)成(cheng)氣(qi)泡(pao)的(de)數(shu)目(mu)便(bian)會(hui)增(zeng)加(jia),而(er)且(qie)由(you)於(yu)溫(wen)度(du)升(sheng)高(gao),粘(zhan)度(du)降(jiang)低(di),使(shi)水(shui)分(fen)、雜質和氣泡在油中形成導電“小橋”,使油的擊穿電壓又很快地下降。尤其是油中雜質和水分都存在時,這種導電“小橋”更易形成,擊穿電壓下降更明顯。
(4)當油中既含有遊離碳,又含有水分時,油的擊穿電壓隨碳微粒量的增加而下降。
(5)油老化後生成的酸等產物,是使水保持乳化狀態的不利因素,因而會使油的擊穿電壓下降;erganzaobuhanshuifendeyou,suandenglaohuachanwuduijichuandianyayingxiangbumingxian,danquenengshijiezhisunhaoyinshujijuzengjia。zheshi,cedingyoudejichuandianyaburucedingjiezhisunhaoyinshugengnengpanduanyoudelaohuachengdudeyuanyinsuozai。
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