1、環境溫濕度

一般材料(liao)(liao)的(de)電(dian)(dian)(dian)阻(zu)值會(hui)隨環(huan)境溫度及濕(shi)(shi)度的(de)升高(gao)而(er)減(jian)小。所以相比較而(er)言，表面電(dian)(dian)(dian)阻(zu)(率(lv))對(dui)環(huan)境濕(shi)(shi)度比較敏(min)感，而(er)體(ti)電(dian)(dian)(dian)阻(zu)(率(lv))則對(dui)溫度較為敏(min)感。濕(shi)(shi)度增加，表面泄(xie)漏增大，體(ti)電(dian)(dian)(dian)導電(dian)(dian)(dian)流(liu)也會(hui)增加。溫度升高(gao)，載流(liu)子的(de)運動速率(lv)加快，介質材料(liao)(liao)的(de)吸(xi)收(shou)電(dian)(dian)(dian)流(liu)和電(dian)(dian)(dian)導電(dian)(dian)(dian)流(liu)會(hui)相應增加，據有關(guan)資料(liao)(liao)報道，一般介質在70C時(shi)的(de)電(dian)(dian)(dian)阻(zu)值僅有20C時(shi)的(de)10％。因此，測量材料(liao)(liao)的(de)電(dian)(dian)(dian)阻(zu)時(shi)，必須指(zhi)明試(shi)樣與環(huan)境達(da)到平(ping)衡(heng)的(de)溫濕(shi)(shi)度。

2、測試電壓及電場強(qiang)度(du)

介(jie)質材(cai)(cai)料(liao)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)阻(zu)(率)值(zhi)一般(ban)不(bu)(bu)能在(zai)很寬的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)壓范(fan)圍內(nei)保持不(bu)(bu)變(bian)(bian)，即歐(ou)姆定律對此(ci)(ci)并(bing)不(bu)(bu)適用(yong)。常(chang)溫條件下(xia)，在(zai)較低的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)壓范(fan)圍內(nei)，電(dian)(dian)(dian)(dian)導(dao)電(dian)(dian)(dian)(dian)流隨外加(jia)(jia)(jia)電(dian)(dian)(dian)(dian)壓的(de)(de)(de)(de)增(zeng)加(jia)(jia)(jia)而線(xian)性(xing)增(zeng)加(jia)(jia)(jia)，材(cai)(cai)料(liao)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)阻(zu)值(zhi)保持不(bu)(bu)變(bian)(bian)。超過(guo)一定電(dian)(dian)(dian)(dian)壓后，由于離子化(hua)運動加(jia)(jia)(jia)劇，電(dian)(dian)(dian)(dian)導(dao)電(dian)(dian)(dian)(dian)流的(de)(de)(de)(de)增(zeng)加(jia)(jia)(jia)遠比測(ce)試(shi)電(dian)(dian)(dian)(dian)壓增(zeng)加(jia)(jia)(jia)的(de)(de)(de)(de)快，材(cai)(cai)料(liao)呈現的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)阻(zu)值(zhi)迅速降低。由此(ci)(ci)可(ke)見，外加(jia)(jia)(jia)測(ce)試(shi)電(dian)(dian)(dian)(dian)壓越高，材(cai)(cai)料(liao)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)阻(zu)值(zhi)越低，以致在(zai)不(bu)(bu)同電(dian)(dian)(dian)(dian)壓下(xia)測(ce)試(shi)得到的(de)(de)(de)(de)材(cai)(cai)料(liao)電(dian)(dian)(dian)(dian)阻(zu)值(zhi)可(ke)能有(you)較大的(de)(de)(de)(de)差別。

值得注意的(de)(de)是，導致材料電(dian)(dian)阻(zu)(zu)值變化的(de)(de)決定因(yin)素是測試(shi)時的(de)(de)電(dian)(dian)場(chang)強度，而不是測試(shi)電(dian)(dian)壓(ya)(ya)。對(dui)相(xiang)同(tong)(tong)的(de)(de)測試(shi)電(dian)(dian)壓(ya)(ya)，若測試(shi)電(dian)(dian)之(zhi)(zhi)間的(de)(de)距離(li)不同(tong)(tong)，對(dui)材料電(dian)(dian)阻(zu)(zu)率的(de)(de)測試(shi)結果也將不同(tong)(tong)，正(zheng)負電(dian)(dian)之(zhi)(zhi)間的(de)(de)距離(li)越小，測試(shi)值也越小。

3、測試時間

用(yong)一定的(de)直流(liu)(liu)電(dian)壓(ya)(ya)(ya)對被(bei)測(ce)材(cai)料加壓(ya)(ya)(ya)時(shi)，被(bei)測(ce)材(cai)料上的(de)電(dian)流(liu)(liu)不是(shi)瞬時(shi)達(da)(da)到(dao)穩(wen)定值(zhi)(zhi)的(de)，而是(shi)有(you)一衰減(jian)過程。在加壓(ya)(ya)(ya)的(de)同時(shi)，流(liu)(liu)過較(jiao)大的(de)充電(dian)電(dian)流(liu)(liu)，接著是(shi)比(bi)較(jiao)長時(shi)間緩慢減(jian)小的(de)吸(xi)收(shou)電(dian)流(liu)(liu)，后達(da)(da)到(dao)比(bi)較(jiao)平(ping)穩(wen)的(de)電(dian)導(dao)電(dian)流(liu)(liu)。被(bei)測(ce)電(dian)阻值(zhi)(zhi)越(yue)高，達(da)(da)到(dao)平(ping)衡的(de)時(shi)間則越(yue)長。因(yin)此，測(ce)量(liang)時(shi)為(wei)了正確讀(du)取(qu)被(bei)測(ce)電(dian)阻值(zhi)(zhi)，應在穩(wen)定后讀(du)取(qu)數值(zhi)(zhi)或取(qu)加壓(ya)(ya)(ya)1分鐘后的(de)讀(du)數值(zhi)(zhi)。

另(ling)外，高絕緣(yuan)材料(liao)的(de)電(dian)阻值還與其(qi)帶電(dian)的(de)歷史有關。為準確(que)評價材料(liao)的(de)靜電(dian)性能，在對材料(liao)進行電(dian)阻(率)測(ce)試(shi)時(shi)(shi)，應首先對其(qi)進行消電(dian)處理，并(bing)靜置一(yi)定的(de)時(shi)(shi)間，靜置時(shi)(shi)間可取5分鐘(zhong)，然后，再(zai)按測(ce)量程序測(ce)試(shi)。一(yi)般而言，對一(yi)種(zhong)材料(liao)的(de)測(ce)試(shi)，至少應隨機抽取3～5個試(shi)樣進行測(ce)試(shi)，以其(qi)平(ping)均(jun)值作(zuo)為測(ce)試(shi)結(jie)果。

4、測試設備的泄漏

在測(ce)(ce)(ce)試中，線路中絕緣電阻不高(gao)的連線，往往會不適(shi)當地與被(bei)測(ce)(ce)(ce)試樣(yang)(yang)、取(qu)樣(yang)(yang)電阻等并聯(lian)，對(dui)測(ce)(ce)(ce)量結(jie)果可能帶來較大的影(ying)響(xiang)。為此：

為減(jian)小測(ce)量誤差，應采用(yong)保(bao)護(hu)技術，在漏電流(liu)大的(de)線路(lu)上安裝保(bao)護(hu)導體，以(yi)基本消除雜(za)散(san)電流(liu)對測(ce)試結果的(de)影響；采用(yong)聚(ju)乙(yi)烯(xi)(xi)、聚(ju)四氟(fu)乙(yi)烯(xi)(xi)等(deng)絕緣材料制作測(ce)試臺和支(zhi)撐體，以(yi)避(bi)免由于該類原因導致(zhi)測(ce)試值偏低。

高電壓線(xian)由于表面(mian)電離，對地有一(yi)定泄漏，所以盡量采(cai)用高絕(jue)緣(yuan)、大線(xian)徑(jing)的(de)高壓導線(xian)作(zuo)為高壓輸出(chu)線(xian)并盡量縮短連(lian)線(xian)，減少，杜絕(jue)電暈放電；

5、外界干擾

高絕(jue)緣材(cai)料加上直流(liu)電(dian)(dian)(dian)(dian)壓后(hou)，通過試(shi)(shi)樣(yang)(yang)的(de)電(dian)(dian)(dian)(dian)流(liu)是(shi)很微小(xiao)(xiao)的(de)，易受到(dao)外界干(gan)擾的(de)影響(xiang)，造成較(jiao)大的(de)測試(shi)(shi)誤差。熱電(dian)(dian)(dian)(dian)勢(shi)(shi)、接觸電(dian)(dian)(dian)(dian)勢(shi)(shi)一般很小(xiao)(xiao)，可以(yi)忽(hu)略；電(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)勢(shi)(shi)主(zhu)要(yao)是(shi)潮濕試(shi)(shi)樣(yang)(yang)與不同金(jin)屬接觸產生的(de)，大約(yue)只(zhi)有20mV，況且在靜電(dian)(dian)(dian)(dian)測試(shi)(shi)中(zhong)均要(yao)求相(xiang)對濕度較(jiao)低，在干(gan)燥環境(jing)中(zhong)測試(shi)(shi)時(shi)，可以(yi)消除(chu)電(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)勢(shi)(shi)。因此，外界干(gan)擾主(zhu)要(yao)是(shi)雜散電(dian)(dian)(dian)(dian)流(liu)的(de)耦(ou)合或(huo)靜電(dian)(dian)(dian)(dian)感應產生的(de)電(dian)(dian)(dian)(dian)勢(shi)(shi)。在測試(shi)(shi)電(dian)(dian)(dian)(dian)流(liu)小(xiao)(xiao)于(yu)10-10A或(huo)測量電(dian)(dian)(dian)(dian)阻(zu)超過1011歐(ou)姆時(shi)；被(bei)測試(shi)(shi)樣(yang)(yang)、測試(shi)(shi)電(dian)(dian)(dian)(dian)和(he)測試(shi)(shi)系(xi)統均應采取(qu)嚴格(ge)的(de)屏(ping)蔽措施，消除(chu)外界干(gan)擾帶來的(de)影響(xiang)。