The PowerWAVE®UPS series transformerless design permits high efficiency AC - AC operation, typically 5% more efficient than a legacy transformer based system.
The Figure below shows efficiency curves for both transformerless and legacy UPSs, highlighting how the transformerless system maintains its 5% advantage across the whole load spectrum from 25% to 100% of full load.
UPSs for Blade Servers
As blade servers become increasingly prevalent in data centres, transformerless UPSs are revealing a further efficiency advantage over legacy systems. Blade servers are popular because they bring high processing density to space constrained environments, but they can impose a leading power factor load on their power supply. At a typical value of PF = 0.9 lead legacy systems can derate by up to 25% compared with transformerless designs, so even more input power is wasted as heat.
Inefficiency of adding a generator
Further consequences will arise if on site generators are used. Because a legacy system derates more severely than a transformerless system under a leading power factor load, its demand for generator size will be greater. Additionally, a legacy system creates a larger input total harmonic distortion (THDi) which also increases the generator oversizing requirement.
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