如果出現單(dan)相(xiang)接(jie)地故障(zhang)，對(dui)地漏電(dian)(dian)流只能經過系(xi)統(tong)(tong)泄露(lu)電(dian)(dian)容對(dui)系(xi)統(tong)(tong)相(xiang)線(xian)構(gou)成回路，而(er)系(xi)統(tong)(tong)泄露(lu)電(dian)(dian)容引(yin)起的(de)容抗總(zong)是遠遠大于TN系(xi)統(tong)(tong)中的(de)接(jie)地電(dian)(dian)阻，因此IT系(xi)統(tong)(tong)中的(de)漏電(dian)(dian)流非(fei)常的(de)小，斷路器不(bu)會(hui)因接(jie)地電(dian)(dian)流的(de)存在而(er)引(yin)起過電(dian)(dian)流動作，從而(er)保(bao)(bao)證(zheng)系(xi)統(tong)(tong)帶故障(zhang)運(yun)行。在電(dian)(dian)氣(qi)上必須保(bao)(bao)證(zheng)醫(yi)用設備(bei)電(dian)(dian)源系(xi)統(tong)(tong)的(de)可(ke)(ke)靠性，既保(bao)(bao)證(zheng)設備(bei)對(dui)患者的(de)直接(jie)測(ce)電(dian)(dian)流不(bu)超過10μA，同(tong)時又要保(bao)(bao)證(zheng)在漏電(dian)(dian)流或過電(dian)(dian)流狀態下，有(you)不(bu)間斷供電(dian)(dian)的(de)可(ke)(ke)靠保(bao)(bao)證(zheng)。在0類和1類醫(yi)院(yuan)場(chang)所，由于無醫(yi)院(yuan)設備(bei)使(shi)用，或相(xiang)關設備(bei)僅使(shi)用在人體些非(fei)致命部位(wei)，所以(yi)可(ke)(ke)使(shi)用普通(tong)建欽物的(de)電(dian)(dian)漂(piao)源各(ge)和漏電(dian)(dian)保(bao)(bao)護措施。

IT系(xi)(xi)(xi)(xi)統中(zhong)(zhong)，IT系(xi)(xi)(xi)(xi)統多少錢一臺(tai)，系(xi)(xi)(xi)(xi)統中(zhong)(zhong)性點(dian)對(dui)地(di)完(wan)全(quan)隔(ge)離(li)，其(qi)電(dian)(dian)氣裝(zhuang)置的(de)(de)(de)外露導(dao)電(dian)(dian)部分，被單獨地(di)或(huo)(huo)集中(zhong)(zhong)地(di)通過保護線(xian)(PE)接(jie)至(zhi)接(jie)地(di)極(ji)。在實(shi)際應用(yong)(yong)(yong)(yong)中(zhong)(zhong)，IT系(xi)(xi)(xi)(xi)統一般與TN或(huo)(huo)TT系(xi)(xi)(xi)(xi)統通過隔(ge)離(li)變壓器進(jin)行隔(ge)離(li)。在正(zheng)常情況下，系(xi)(xi)(xi)(xi)統中(zhong)(zhong)僅存在線(xian)路(lu)對(dui)地(di)電(dian)(dian)容的(de)(de)(de)微(wei)小(xiao)泄漏電(dian)(dian)流(liu)(liu)。圖1所(suo)示為IT系(xi)(xi)(xi)(xi)統發生一次接(jie)地(di)故(gu)(gu)障示意圖，當系(xi)(xi)(xi)(xi)統發生1次單相接(jie)地(di)故(gu)(gu)障時，故(gu)(gu)障電(dian)(dian)流(liu)(liu)為兩非故(gu)(gu)障相對(dui)地(di)電(dian)(dian)容電(dian)(dian)流(liu)(liu)的(de)(de)(de)相量(liang)和Id，由于這個電(dian)(dian)流(liu)(liu)值甚小(xiao)，不(bu)會造(zao)成人身電(dian)(dian)流(liu)(liu)或(huo)(huo)者其(qi)它事故(gu)(gu)，也(ye)不(bu)會切(qie)斷電(dian)(dian)源，保證(zheng)了(le)系(xi)(xi)(xi)(xi)統供(gong)(gong)電(dian)(dian)的(de)(de)(de)連續(xu)性。正(zheng)是(shi)由于IT系(xi)(xi)(xi)(xi)統的(de)(de)(de)供(gong)(gong)電(dian)(dian)的(de)(de)(de)連續(xu)可靠(kao)性，國家規范已明確要求(qiu)：在醫(yi)用(yong)(yong)(yong)(yong)領域2類醫(yi)用(yong)(yong)(yong)(yong)場所(suo)內(nei)，用(yong)(yong)(yong)(yong)于維持(chi)生命(ming)的(de)(de)(de)、手術的(de)(de)(de)和其(qi)他(ta)位(wei)于“患(huan)者區域內(nei)的(de)(de)(de)醫(yi)用(yong)(yong)(yong)(yong)電(dian)(dian)器設(she)備和系(xi)(xi)(xi)(xi)統的(de)(de)(de)供(gong)(gong)電(dian)(dian)回路(lu)應選用(yong)(yong)(yong)(yong)帶絕緣監視的(de)(de)(de)醫(yi)用(yong)(yong)(yong)(yong)IT系(xi)(xi)(xi)(xi)統供(gong)(gong)電(dian)(dian)。

在(zai)電(dian)(dian)(dian)(dian)(dian)氣上必須保(bao)(bao)證(zheng)醫(yi)用(yong)設(she)備(bei)(bei)電(dian)(dian)(dian)(dian)(dian)源系統的(de)可(ke)靠(kao)性，既保(bao)(bao)證(zheng)設(she)備(bei)(bei)對(dui)患者(zhe)的(de)直接測電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)不(bu)超過(guo)10μA，同時又要保(bao)(bao)證(zheng)在(zai)漏電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)或(huo)過(guo)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)狀態(tai)下，有不(bu)間斷(duan)供電(dian)(dian)(dian)(dian)(dian)的(de)可(ke)靠(kao)保(bao)(bao)證(zheng)。通(tong)過(guo)單相0.5kVA-10kVA的(de)隔(ge)離(li)變壓器給這些場(chang)所供電(dian)(dian)(dian)(dian)(dian)，首先(xian)可(ke)以防(fang)止(zhi)其(qi)他供電(dian)(dian)(dian)(dian)(dian)回路中的(de)漏電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)通(tong)過(guo)接地(di)線(xian)竄入(ru)手術(shu)室(shi)(shi)及監護室(shi)(shi)(ICU)、心臟(zang)監護室(shi)(shi)(CCU) 的(de)醫(yi)用(yong)電(dian)(dian)(dian)(dian)(dian)器設(she)備(bei)(bei)上對(dui)患者(zhe)的(de)安(an)全構成威脅(xie)。在(zai)0類和(he)(he)1類醫(yi)院場(chang)所，由(you)于無醫(yi)院設(she)備(bei)(bei)使(shi)(shi)用(yong)，或(huo)相關設(she)備(bei)(bei)僅使(shi)(shi)用(yong)在(zai)人(ren)體些非致命部位，所以可(ke)使(shi)(shi)用(yong)普通(tong)建欽物的(de)電(dian)(dian)(dian)(dian)(dian)漂源各和(he)(he)漏電(dian)(dian)(dian)(dian)(dian)保(bao)(bao)護措施(shi)。