High-efficiency UPS protection for IT equipment

Double-conversion UPS are often the preferred choice for protecting critical loads, the typical example being IT equipment in data centres. While providing optimum protection, double-conversion UPS only provide limited efficiency. Some UPS feature a high-efficiency operating mode (so-called ECO mode) where the load is fed via the bypass path. Particularly, some Advanced ECO mode implementations combine efficiency with a very fast transfer to inverter when the utility voltage is going out of given tolerances. Traditionally, market adoption of these technologies has been limited, following concerns on exposure of the load to utility disturbances. This paper aims to clear these concerns by presenting experimental results from testing real IT equipment with UPS protection operating in Advanced ECO Mode. Particularly, the system has been exposed to common power quality events on the UPS input utility, while evaluating the residual effect on the IT equipment power supply.