TRENDS IN PF OF DATA CENTRE UPS LOADS AND WHAT TO DO ABOUT THEM

摘要

During the past few years, data centre equipment has moved towards a dual-corded model, wherein the two cords are able to power a critical network component from two diverse supplies. Concurrently, power supply design has been modified to meet IEEE 519 and EN/IEC 610000-3-2 harmonic requirements, and to meet the International Technology Industry Council (ITIC) revised voltage performance curve (which superseded the previous CBEMA envelope). Some of the methods used to meet the EN/IEC and ITIC requirements are not ideally suited when used as a partly idle power supply on dual-corded equipment, as they present a leading power factor to the UPS or other source. As the proportion of partly unloaded power supplies grows, the overall power factor swings through unity to leading, something that many UPS systems and most generators are not intended to deal with. The result is de-rating of power supply infrastructure, which is eventually unable to deliver its intended capacity to the data centre load. This paper examines the reasons for this trend, and presents the results of investigations into some of the solutions that can be applied to recover the intended power system ratings.