當(dang)市電(dian)(dian)供(gong)(gong)電(dian)(dian)中斷或(huo)市電(dian)(dian)電(dian)(dian)壓(ya)超限 (±15%或(huo)±20%額定輸入電(dian)(dian)壓(ya))時,互投裝置將(jiang)立(li)即投切至逆變器(qi)供(gong)(gong)電(dian)(dian),在電(dian)(dian)池組(zu)所提供(gong)(gong)的(de)直流能源的(de)支(zhi)持下(xia),此時,用(yong)戶負載(zai)所使用(yong)的(de)電(dian)(dian)源是(shi)通過EPS的(de)逆變器(qi)轉換的(de)交流電(dian)(dian)源,而不是(shi)來自(zi)市電(dian)(dian)