當市電(dian)(dian)(dian)供電(dian)(dian)(dian)中(zhong)斷或(huo)市電(dian)(dian)(dian)電(dian)(dian)(dian)壓超限 (±15%或(huo)±20%額定(ding)輸入電(dian)(dian)(dian)壓)時(shi),互投(tou)裝置將立即投(tou)切(qie)至逆變(bian)器供電(dian)(dian)(dian),在電(dian)(dian)(dian)池組所提供的(de)直(zhi)流(liu)能源的(de)支持下,此時(shi),用(yong)(yong)戶負載所使(shi)用(yong)(yong)的(de)電(dian)(dian)(dian)源是(shi)通過EPS的(de)逆變(bian)器轉換(huan)的(de)交流(liu)電(dian)(dian)(dian)源,而不是(shi)來自市電(dian)(dian)(dian)