At the end of December the U.S. Department of Energy (DOE), has issued the first-ever energy efficiency standards for uninterruptible power supplies (UPS). According to the DOE, the new UPS standards will mean 87 billion kilowatt-hours of electricity saved over the next three decades. This represents an energy savings of 15 percent relative to the electricity consumption of these products in the absence of an efficiency standard.
The department‘s analysis lists variety of technology options that manufacturers can use to improve the efficiency of their products.
„DOE identified three technology options for UPSs that would be expected to improve the efficiency of UPSs. The technologies options are: semiconductor improvements, digital signal processing and space vector modulation, and transformer-less UPS topologies.“
„Transformer-less UPS designs offer some of the highest efficiencies in the industry with lowered weight, wider input voltage tolerances, near unity input power factor, reduced harmonic distortion and need for components that mitigate electromagnetic interference (EMI) generated by the device.“
For the sake of completeness one must also say, that the DEO did not evaluate transformer-less UPS design because „interviews with manufacturers have shown this to be a limited access technology with select manufacturers holding the intellectual property required for effective implementation.“
However, the DOE does not prescribe how manufacturers should make their products more efficient. The standards are being set in a performance-based manner, allowing manufacturers the flexibility to innovate. Thus, the document can also be interpreted in such a way that transformer-less UPS design is always a future-proof choice in terms of efficiency.
Chris Granda, blogger at Appliance Standards Awareness Project, comments:
„Had DOE included transformer-less design in their analysis, we believe even stronger UPS efficiency standards would have been justified.“