Page "Uninterruptible power supply" Paragraph 54

The way efficiency is measured varies massively in the UPS market, and there are a number of reasons for this.

Many UPS manufacturers claim to have the highest level of efficiency, often using different sets of criteria in order to reach these figures.

The industry norm can be argued to be anything between 93 %- 96 % when a UPS is in full operational mode, and to reach these figures companies often put their UPS in an ideal scenario.

Efficiency figures on site are often much closer to the 90 % mark, due to varying power conditions.

The perfect scenario will never happen in reality, due to ongoing voltage sags from the mains and the declining efficiency of UPS batteries.