The right UPS for your application is determined by several factors. To select the right UPS you will need to know:

• The power requirement of your equipment load. How much electric current does your equipment need? This is usually measured in amps (current) or watts (power).
• How long does the UPS need to support operation of the equipment in case of a black-out? This will be UPSs required "run time".
• How critical is the application? Of course, any application is important if you are considering a UPS. However, since the most reliable on-line UPS models are more expensive than the simpler stand-by models it is best to match the features of the UPS with the value of the application.

The UPS models are described based on their power rating in terms of their wattage (W) rating. Match this with the power requirement of your application. The run-time of the UPS is stated for full capacity current draw and one-half capacity. The most critical applications (security or network communications) should probably be supported by an on-line model. The less critical applications (cash registers or work stations) are usually matched with a stand-by device.