當市(shi)電(dian)(dian)(dian)供(gong)電(dian)(dian)(dian)中斷或(huo)市(shi)電(dian)(dian)(dian)電(dian)(dian)(dian)壓超限 (±15%或(huo)±20%額定輸入(ru)電(dian)(dian)(dian)壓)時,互投(tou)裝(zhuang)置將立(li)即投(tou)切至逆(ni)變器(qi)供(gong)電(dian)(dian)(dian),在電(dian)(dian)(dian)池組所提供(gong)的(de)直流(liu)能源(yuan)的(de)支持下,此時,用(yong)戶(hu)負載(zai)所使用(yong)的(de)電(dian)(dian)(dian)源(yuan)是通(tong)過(guo)EPS的(de)逆(ni)變器(qi)轉換(huan)的(de)交流(liu)電(dian)(dian)(dian)源(yuan),而不是來自市(shi)電(dian)(dian)(dian)