當(dang)市電(dian)(dian)供(gong)電(dian)(dian)中(zhong)斷(duan)或市電(dian)(dian)電(dian)(dian)壓(ya)(ya)超限 (±15%或±20%額定輸入電(dian)(dian)壓(ya)(ya))時,互投(tou)裝置將立即投(tou)切至逆(ni)變器供(gong)電(dian)(dian),在電(dian)(dian)池組所(suo)提供(gong)的(de)直流能源的(de)支持下,此時,用戶負載(zai)所(suo)使(shi)用的(de)電(dian)(dian)源是通過EPS的(de)逆(ni)變器轉換的(de)交流電(dian)(dian)源,而(er)不(bu)是來自市電(dian)(dian)