The S3K uninterruptible power supply mini-tower is an economical choice for those applications requiring the performance of a sinewave output, line interactive UPS with the mini-tower shape for cabinet installations. The S3K Series uninterruptible power supply protects against most severe power disturbances including over/under voltages through state of art, line-interactive technology - most power disturbance corrections are accomplished without transferring to the internal battery. Utility power is continually protected by the S3K Series UPS’s and internal battery life is optimized. The uninterruptible power supply has built in protection for under and over voltage conditions including low-energy lightning surges introduced on the input power source. All S3K Series UPS are provided with an input circuit protector and surge protected data line connectors. The S3K Series UPS’s are provided with a battery test function to insure the capability of the battery to supply power in emergency situations. Should the battery fail this test, the uninterruptible power supply will display a warning to indicate that the battery needs to be replaced.