當市電(dian)(dian)供電(dian)(dian)中斷或市電(dian)(dian)電(dian)(dian)壓超限 (±15%或±20%額定(ding)輸入電(dian)(dian)壓)時,互投(tou)裝(zhuang)置將立(li)即(ji)投(tou)切至逆變器供電(dian)(dian),在電(dian)(dian)池(chi)組所提供的(de)(de)直流(liu)能(neng)源的(de)(de)支持(chi)下,此時,用戶負載所使用的(de)(de)電(dian)(dian)源是通過(guo)EPS的(de)(de)逆變器轉換的(de)(de)交流(liu)電(dian)(dian)源,而不(bu)是來自(zi)市電(dian)(dian)