How to Choose an Uninterruptible Power Supply

An uninterruptible power supply (UPS) is the most effective way to protect your computer hardware and documents from power fluctuations. It also lets you continue to work during brief power failures.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Uninterruptible Power Supplies

1. If you have a limited budget, choose a standby (also called "off-line") UPS that switches to battery power when power goes out.

2. Choose an "on-line" UPS if you need unlimited backup power.

3. Select a "line-interactive" UPS if your needs fall between the two other types.

4. Determine the total power needs (in watts and volt-amperes) of equipment you will connect to the UPS.

5. Choose a UPS that equals or exceeds the total power requirements of the equipment that you'll connect to it.

6. Compare the following five specifications for different models: maximum surge current (expressed in amps - more is better), surge suppression (expressed in joules - more is better), suppression response time (faster is better), battery recharge time (faster is better), and number of AC outlets (more is better).

7. Find out if the unit under consideration has a replaceable battery, and if the battery is user-replaceable.

8. Compare battery operating times (how long the UPS will keep equipment running after power failure).

9. Look for a unit with modem surge protection and electromagnetic interference (EMI) and radio-frequency interference (RFI) noise reduction if you need those features.

10. Check for alarms or LEDs that indicate wiring problems, whether the equipment is running on UPS battery, and whether the battery is low.

11. If you are buying a more expensive unit, get one with software that automatically saves documents, closes applications, and turns off equipment when power goes out.

12. Compare warranties and insurance guarantees.

Tips & Warnings

• You can sometimes find wattage and volt-amperage of your computer equipment in the manual or on a sticker on the chassis.
• If your computer was custom-made, the person who built it should be able to provide the wattage and volt-amperage information.
• Whether you need EMI and RFI protection depends on the quality of your electricity and the amount of other electronic equipment in the vicinity of your computer.