當(dang)市電(dian)(dian)(dian)(dian)供(gong)電(dian)(dian)(dian)(dian)中(zhong)斷或(huo)市電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓超(chao)限 (±15%或(huo)±20%額定(ding)輸入電(dian)(dian)(dian)(dian)壓)時,互投(tou)裝置將立即投(tou)切至逆(ni)變器(qi)供(gong)電(dian)(dian)(dian)(dian),在電(dian)(dian)(dian)(dian)池組(zu)所提供(gong)的(de)直流(liu)能源(yuan)的(de)支持下,此時,用戶負載(zai)所使用的(de)電(dian)(dian)(dian)(dian)源(yuan)是通過EPS的(de)逆(ni)變器(qi)轉換的(de)交(jiao)流(liu)電(dian)(dian)(dian)(dian)源(yuan),而不(bu)是來自市電(dian)(dian)(dian)(dian)