當市電(dian)(dian)供電(dian)(dian)中斷(duan)或(huo)市電(dian)(dian)電(dian)(dian)壓(ya)超限 (±15%或(huo)±20%額(e)定輸入電(dian)(dian)壓(ya))時,互投(tou)裝置將立即(ji)投(tou)切至逆變(bian)器供電(dian)(dian),在電(dian)(dian)池組所提供的直(zhi)流能源的支持下,此(ci)時,用戶負載所使用的電(dian)(dian)源是(shi)(shi)通過EPS的逆變(bian)器轉換(huan)的交流電(dian)(dian)源,而不是(shi)(shi)來自市電(dian)(dian)