The terms Power Factor, Crest Factor, and Surge Factor refer to completely different and unrelated phenomena. These characteristics are often specified for UPS systems, and customers will sometimes place them in specifications.

Most UPS systems today have sufficient Crest Factor and Surge Factor to meet virtually any requirement in a data room or data center. Therefore, their use in bid specifications is relatively unimportant.

Power Factor remains a misunderstood subject, and ignoring or misapplying the power factor concepts can result in a number of problems, including: overestimation of UPS run time; incorrect comparison of run time between competitive products, and under sizing of UPS systems. The guidelines and warnings regarding power factor that are summarized in this paper can prevent these misunderstandings.