T系(xi)統與(yu)應(ying)急(ji)電源的(de)區別(bie);應(ying)急(ji)電源（UPS/EPS）是(shi)在(zai)(zai)正常供電線路電力中(zhong)斷時的(de)后備應(ying)急(ji)電源，不能(neng)防范接地(di)(di)故障。在(zai)(zai)普通(tong)的(de)接地(di)(di)系(xi)統（TN-S系(xi)統）內(nei)負載(zai)端出現對地(di)(di)故障時，不管該系(xi)統使用的(de)是(shi)應(ying)急(ji)電源還是(shi)普通(tong)的(de)供電線路，都不能(neng)限制(zhi)故障電流(liu)的(de)增大，只有采(cai)用IT系(xi)統后才(cai)能(neng)大限度地(di)(di)限制(zhi)故障電流(liu)，達到接地(di)(di)保護(hu)的(de)目的(de)。

醫(yi)用IT系(xi)統(tong)(tong)（俗稱醫(yi)用隔離(li)電(dian)源系(xi)統(tong)(tong)），醫(yi)用it系(xi)統(tong)(tong)批發，又叫(jiao)中(zhong)(zhong)性點(dian)不接地(di)(di)配電(dian)系(xi)統(tong)(tong)。在IT系(xi)統(tong)(tong)中(zhong)(zhong)，系(xi)統(tong)(tong)中(zhong)(zhong)性點(dian)對(dui)(dui)地(di)(di)完全隔離(li)，系(xi)統(tong)(tong)負載中(zhong)(zhong)的(de)外殼經接地(di)(di)保護線接地(di)(di)。如果出現(xian)單(dan)相(xiang)接地(di)(di)故(gu)障，對(dui)(dui)地(di)(di)漏(lou)電(dian)流只能經過系(xi)統(tong)(tong)泄露電(dian)容(rong)對(dui)(dui)系(xi)統(tong)(tong)相(xiang)線構成回路，而(er)系(xi)統(tong)(tong)泄露電(dian)容(rong)引起的(de)容(rong)抗(kang)總是遠(yuan)遠(yuan)大(da)于(yu)TN系(xi)統(tong)(tong)中(zhong)(zhong)的(de)接地(di)(di)電(dian)阻(zu)，因此IT系(xi)統(tong)(tong)中(zhong)(zhong)的(de)漏(lou)電(dian)流非常的(de)小，斷路器不會因接地(di)(di)電(dian)流的(de)存在而(er)引起過電(dian)流動作(zuo)，從而(er)保證系(xi)統(tong)(tong)帶(dai)故(gu)障運行(xing)。

醫(yi)用(yong)(yong)IT系(xi)統是(shi)(shi)指:醫(yi)用(yong)(yong)IT系(xi)統中(zhong)(zhong)的(de)(de)(de)電(dian)氣(qi)設(she)備(bei)有外露導電(dian)部分通(tong)過保(bao)護(hu)線接地．而電(dian)源隔(ge)離(li)回(hui)路(lu)中(zhong)(zhong)的(de)(de)(de)設(she)備(bei)外殼(ke)不(bu)(bu)做(zuo)接地。它是(shi)(shi)采用(yong)(yong)特(te)低電(dian)壓回(hui)路(lu)輔以(yi)不(bu)(bu)接地的(de)(de)(de)等(deng)電(dian)位連接（將電(dian)源隔(ge)離(li)區域內的(de)(de)(de)各個電(dian)氣(qi)設(she)備(bei)金屬(shu)外殼(ke)用(yong)(yong)絕緣導線互相連通(tong)）來(lai)獲得好的(de)(de)(de)安全的(de)(de)(de)效(xiao)果。電(dian)源隔(ge)離(li)適用(yong)(yong)于浴室、游泳池(chi)等(deng)危險大，對不(bu)(bu)間斷(duan)供電(dian)無特(te)殊要求(qiu)的(de)(de)(de)潮濕(shi)場所。