當市(shi)電(dian)(dian)(dian)(dian)供電(dian)(dian)(dian)(dian)中斷(duan)或市(shi)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓(ya)(ya)超(chao)限 (±15%或±20%額(e)定輸入(ru)電(dian)(dian)(dian)(dian)壓(ya)(ya))時,互投(tou)裝置將立(li)即投(tou)切(qie)至逆變(bian)(bian)器供電(dian)(dian)(dian)(dian),在(zai)電(dian)(dian)(dian)(dian)池(chi)組所提供的直流(liu)能(neng)源的支持(chi)下,此(ci)時,用(yong)戶(hu)負(fu)載所使用(yong)的電(dian)(dian)(dian)(dian)源是(shi)通過EPS的逆變(bian)(bian)器轉換(huan)的交流(liu)電(dian)(dian)(dian)(dian)源,而不是(shi)來(lai)自市(shi)電(dian)(dian)(dian)(dian)