Rackmount UPS Power Supply

Power Distribution Unit

How to Select Powercom UPS

1. Capacity Rating – Rated power capacity normally in Watt (W) and also expressed in Volt-
Amps (VA). To calculate the VA load of your system, check the UL label for the operating
voltage and amperage drawn*. The conversion of Volt-Ampere rating to Watts is dependents
on the load power factor (pf). A power Factor value is determined by the load. For UPS, use pf
of 0.6

Add the amperage of each component to be powered by the UPS and multiply the number by
the voltage (120V for US applications). This number is your VA load and the minimum size

Computer: 180 Watt power supply =>180W ¸ 0.6 = 300VA load
Speaker: 0.5 Amp power supply => 0.5A x 120V = 60VA load
Monitor: 1 Amp => 1 A x 120V = 120VA load
Total: 480VA load (Minimum VA required)

Powercom recommends you to get additional 30 ~ 50 % more VA/Watts on your UPS for
others and future usage purpose, it is also helpful to increase battery backup time.
So, 480VA x 1.3 = 624VA. Therefore, you need a 625 ~ 800VA UPS (Ideal size)

For example (King Pro Series):
VA 425 625 800 1000 1200 1500 2200 3000
Watts 255 375 480 600 720 900 1320 1800

* Note: many computers’UL labels list 3 or 4 amps. This is a maximum draw. Typical
computer will draw 1 to 2 amps under a standard configuration.

2. Backup Time

Length of backup time depends on the loading, battery condition and model. It is important to
choose the right VA. Once you have calculated the VA load, you can compare the full and half
load backup time in different models.


1 pc with a 15” monitor
If you bundle a SLIKP-2200APM, your estimated backup time is 80 to 90 mins.