因此對電(dian)(dian)(dian)(dian)氣(qi)安(an)全設計也(ye)提(ti)出了特殊的(de)要(yao)求。手術室、ICU、CCU病房等這(zhe)些對電(dian)(dian)(dian)(dian)力(li)(li)可靠性(xing)要(yao)求很高的(de)場所，不管出現任(ren)何(he)情況，都應保證電(dian)(dian)(dian)(dian)力(li)(li)供(gong)應的(de)連續(xu)性(xing)和預防微電(dian)(dian)(dian)(dian)，否則，將導(dao)致因維持生命的(de)設備斷(duan)電(dian)(dian)(dian)(dian)或漏電(dian)(dian)(dian)(dian)而對患者造成(cheng)生命危險。一般供(gong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)網是(shi)以大地(di)作(zuo)為(wei)參考(kao)電(dian)(dian)(dian)(dian)位(wei)，相線中的(de)電(dian)(dian)(dian)(dian)流可以通(tong)過(guo)任(ren)何(he)未絕緣的(de)通(tong)道，對地(di)構成(cheng)回路，這(zhe)是(shi)的(de)根本原(yuan)因。隔離(li)(li)供(gong)電(dian)(dian)(dian)(dian)是(shi)采用(yong)隔離(li)(li)變壓(ya)器(qi)(qi)供(gong)電(dian)(dian)(dian)(dian)，電(dian)(dian)(dian)(dian)源經隔離(li)(li)變壓(ya)器(qi)(qi)隔離(li)(li)后，原(yuan)電(dian)(dian)(dian)(dian)網中的(de)地(di)已不再是(shi)參考(kao)電(dian)(dian)(dian)(dian)位(wei)。該系統接地(di)故障(zhang)多為(wei)金屬性(xing)短(duan)路，因故障(zhang)電(dian)(dian)(dian)(dian)流較(jiao)大，使斷(duan)路器(qi)(qi)或熔斷(duan)器(qi)(qi)等過(guo)電(dian)(dian)(dian)(dian)流保護(hu)裝(zhuang)置(zhi)動作(zuo)，造成(cheng)房間停電(dian)(dian)(dian)(dian)。顯然TN—S系統不能(neng)滿(man)足醫院(yuan)中一些重要(yao)場所對不間斷(duan)供(gong)電(dian)(dian)(dian)(dian)的(de)實用(yong)要(yao)求

IT 系統(tong)的(de)(de)(de)(de)組(zu)成:醫(yi)用(yong)(yong)(yong)IT 系統(tong)主要由三部分組(zu)成 ：醫(yi)用(yong)(yong)(yong)隔(ge)離(li)(li)變壓(ya)器(qi)、絕(jue)(jue)緣(yuan)(yuan)(yuan)監(jian)視(shi)器(qi)及(ji)外(wai)接報警顯示和測(ce)試(shi)單元。普遍采用(yong)(yong)(yong)帶絕(jue)(jue)緣(yuan)(yuan)(yuan)監(jian)視(shi)裝置(zhi)的(de)(de)(de)(de)醫(yi)用(yong)(yong)(yong)IT 系統(tong)（隔(ge)離(li)(li)電(dian)(dian)源），即采用(yong)(yong)(yong)不接地(di)電(dian)(dian)源系統(tong)為(wei)2 類醫(yi)用(yong)(yong)(yong)場所供(gong)電(dian)(dian)。醫(yi)用(yong)(yong)(yong)隔(ge)離(li)(li)電(dian)(dian)源，簡言之就是隔(ge)離(li)(li)變壓(ya)器(qi)和絕(jue)(jue)緣(yuan)(yuan)(yuan)監(jian)視(shi)儀以及(ji)報警終端(duan)放(fang)在(zai)一起。供(gong)電(dian)(dian)原理是利(li)用(yong)(yong)(yong)隔(ge)離(li)(li)變壓(ya)器(qi)把TN供(gong)電(dian)(dian)變成不接地(di)的(de)(de)(de)(de)IT 供(gong)電(dian)(dian)，為(wei)了(le)保(bao)證系統(tong)的(de)(de)(de)(de)長期(qi)穩(wen)定(ding)性(xing)(xing)，應加上絕(jue)(jue)緣(yuan)(yuan)(yuan)監(jian)測(ce)儀對整體的(de)(de)(de)(de)絕(jue)(jue)緣(yuan)(yuan)(yuan)水平進行在(zai)線的(de)(de)(de)(de)實時檢測(ce)。既然規(gui)范對醫(yi)用(yong)(yong)(yong)場所設置(zhi)IT系統(tong)有了(le)較(jiao)明(ming)確的(de)(de)(de)(de)規(gui)定(ding)，但只有設計者能夠正確理解并充分認識到(dao)醫(yi)用(yong)(yong)(yong)場所選用(yong)(yong)(yong)IT 系統(tong)的(de)(de)(de)(de)必要性(xing)(xing)和特殊性(xing)(xing)，才(cai)能合理運用(yong)(yong)(yong)。

醫用(yong)(yong)隔離電(dian)(dian)源降低了對(dui)(dui)地(di)(di)漏(lou)電(dian)(dian)流(liu)(liu)(liu)，故提(ti)高了防火安全性(xing)。醫院(yuan)在對(dui)(dui)醫用(yong)(yong)設(she)備(bei)(bei)故障檢修(xiu)(xiu)維修(xiu)(xiu)時，經常(chang)需要在通(tong)電(dian)(dian)狀(zhuang)態下接觸(chu)電(dian)(dian)路(lu)(lu)中(zhong)的(de)(de)(de)元器件或電(dian)(dian)路(lu)(lu)中(zhong)的(de)(de)(de)地(di)(di)線(xian)，使用(yong)(yong)醫用(yong)(yong)隔離電(dian)(dian)源可以(yi)防止醫院(yuan)設(she)備(bei)(bei)維修(xiu)(xiu)人員觸(chu)電(dian)(dian)的(de)(de)(de)危險。一(yi)旦隔離電(dian)(dian)源上(shang)所接的(de)(de)(de)各種醫用(yong)(yong)設(she)備(bei)(bei)出現(xian)對(dui)(dui)地(di)(di)故障，it系(xi)統絕緣監(jian)測器，因其對(dui)(dui)地(di)(di)不能(neng)(neng)構成回路(lu)(lu)，所以(yi)只(zhi)能(neng)(neng)產生一(yi)個很(hen)小的(de)(de)(de)容性(xing)漏(lou)電(dian)(dian)流(liu)(liu)(liu)，極大地(di)(di)保(bao)護了患者免遭(zao)漏(lou)電(dian)(dian)流(liu)(liu)(liu)的(de)(de)(de)傷(shang)害。如果出現(xian)單(dan)相(xiang)(xiang)接地(di)(di)故障，對(dui)(dui)地(di)(di)漏(lou)電(dian)(dian)流(liu)(liu)(liu)只(zhi)能(neng)(neng)經過系(xi)統泄露(lu)電(dian)(dian)容對(dui)(dui)系(xi)統相(xiang)(xiang)線(xian)構成回路(lu)(lu)，而(er)(er)系(xi)統泄露(lu)電(dian)(dian)容引(yin)起的(de)(de)(de)容抗(kang)總是遠遠大于TN系(xi)統中(zhong)的(de)(de)(de)接地(di)(di)電(dian)(dian)阻(zu)，因此IT系(xi)統中(zhong)的(de)(de)(de)漏(lou)電(dian)(dian)流(liu)(liu)(liu)非常(chang)的(de)(de)(de)小，斷路(lu)(lu)器不會(hui)因接地(di)(di)電(dian)(dian)流(liu)(liu)(liu)的(de)(de)(de)存在而(er)(er)引(yin)起過電(dian)(dian)流(liu)(liu)(liu)動作，從而(er)(er)保(bao)證系(xi)統帶故障運(yun)行。