The invention discloses a UPS (Uninterrupted Power
System), and the
system comprises an air
circuit breaker Q1, an air
circuit breaker Q2, a maintenance bypass air switch Q3BP, a bypass static switch, a rectification module REC, an inversion module INV, an output
isolation transformer TR2, a main circuit static switch, an air
circuit breaker Q5, a contact-type normally-opened contact KM, and a storage battery. A main input circuit
AC power supply is inputted from the air circuit breaker Q1, and the
AC power supply is converted into a DC power supply through the rectification module REC, thereby completing the AC / DC conversion, so as to charge the storage battery in parallel connection with a main input circuit and to provide a reliable input
direct current for the inversion module INV. The inversion module INV carries out the DC / AC conversion, and converts the DC power supply provided by the rectification module REC and the storage battery into the
AC power supply. The AC power supply is outputted through the output
isolation transformer TR2. A bypass input power supply is inputted from the air circuit breaker Q2, and is controlled by the bypass static switch and then is outputted. The UPS is stable in
voltage, is quick and efficient, is simple in operation, and is convenient to maintain.