Question : Problem: APC Smart UPS 1400XL

the way I understand the APC UPS is that with a 1400XL, I can plug 1400 watts of power into it.    My confusion is this UPS is running at 60% load when I have a HP Proliant ML350 G2 with redundant power supplies plugged in.    According to the documentation, each power supply is 700 watts.   With both power supplies plugged in, this UPS should be at 100%.    What am I missing?

Answer : Problem: APC Smart UPS 1400XL

First, a 1400XL is rated for 1400VA, which is not the same as 1400 watts.  You multiply the VA by the efficiency rating to get the watts it can handle, which is typically 0.7, so that APC unit can handle 1400 * 0.7 = 980 watts.

Second, a power supply does not run at maximum capacity when it doesn't need to - your total load is less than the maximum 700 watts of the power supply, and depends on what is in the system.  Use a Kill-A-Watt device to measure actual power usage during operation.

Third, redundant power supplies do not draw maximum current simultaneously; they are designed to switch over to the working one when the other fails.