Main Features: a. True on-line double conversion technology with advanced microprocessor control b. Wide input voltage range with high frequency technology c. Zero transfer time d. Protection against all type of power problems e. ups power supply 3kva has the self test while start f. Site wiring fault warning g. On-battery power-on function h. Smart RS232 communication interface i. Intelligent slot available j. Sealed acid battery,free-maintenance battery in online ups 220v.