OFF-LINE UPS
Lower cost than other units
Under mains power unit charges batteries and power passes directly to the load
During mains failure batteries provide power to DC/AC inverter to provide 230VAC power to the load
Square-wave or Sine-wave output

ON-LINE UPS
Constant duty inverter
Design inherently improves power quality and reliability
No break
Sine-wave output
Static bypass improves reliability

LINE INTERACTIVE UPS

These UPS offer enhanced power protection over the basic off-line designs because they provide additional line conditioning. They can also cope with a wider range of input voltages without resorting to battery.