當市電(dian)(dian)供電(dian)(dian)中斷或市電(dian)(dian)電(dian)(dian)壓超限 (±15%或±20%額定(ding)輸入電(dian)(dian)壓)時,互(hu)投裝置將立即投切(qie)至逆(ni)變器供電(dian)(dian),在電(dian)(dian)池組所提供的(de)(de)(de)直流能源的(de)(de)(de)支持下,此(ci)時,用戶負載所使用的(de)(de)(de)電(dian)(dian)源是通過EPS的(de)(de)(de)逆(ni)變器轉(zhuan)換的(de)(de)(de)交(jiao)流電(dian)(dian)源,而不是來自市電(dian)(dian)