City electricity have trouble normally, export one and import in-phase 220 V AC frequently by machine this, when losing electrical power or the voltage is too low, (10 milliseconds) are supplied power by the battery within extremely short time, go against person who become send out by INVERTER 220 V AC continue load of supplying with, supply power in duration in about 4 minutes, if in the period of supplying power of battery, the electricity resumes, go against the becoming device and stop generating electricity in the machine immediately in the city, going back to the city electricity will supply power to load automatically, meanwhile, charge the battery with charger, until its specified value.UPS.