Avoiding Pitfalls in Coordination of Multi-Mode UPS and STS L Giuntini

 Session F1.04 - Avoiding pitfalls in coordination of multi-mode UPS and STS L Giuntini From: PEMD 2014, Session F1: Energy Conversion and Storage, 8 - 10 April 2014, Manchester 08 April 2014 Power channel

1.Introduction
 Uninterruptible Power Supplies (UPS) provide power conditioning and backup for mission critical applications, the typical example being the protection of Information Technology (IT) equipment in data centres installations. In this context, double-conversion is the preferred UPS topology [1], following the superior protection offered by the AC-DCAC conversion. However, the multiple conversion steps limit the efficiency of such topology. Therefore, some doubleconversion UPS have evolved towards Multi-mode operation, where efficiency is maximized by selecting the operating mode depending on the environmental conditions (namely, the power quality of the input mains). Performance of Multimode UPS and compatibility with the typical load requirements have been extensively discussed in [2, 3, 4]. At the same time, applications requiring the highest level of availability may improve their distribution reliability by means of redundancy. Particularly, multiple sources may be tied together by means of Static Transfer Switches (STS). These devices may switch between separate sources whenever the voltage of the active source is sensed as going out of given tolerances, just as in Multi-mode UPS. Therefore, the application of Multi-mode UPS operation and STS protection in the same installation poses significant challenges. This paper addresses the coordination of Multimode UPS and downstream STS by highlighting common pitfalls to be avoided,
2 Multi-mode UPS
Figure 1 depicts a basic block diagram for a doubleconversion
transformer-based UPS

GE Consumer & Industrial SA, Via Cantonale 50,CH-6595 Riazzino, Switzerland, lorenzo.giuntini@ge.com
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