All electronics are really DC powered, even though they are fed AC from the grid, which means that each TV, DVD, SAT, stereo, computer, etc., has a transformer+rectifier inside. How efficient is that? Would it be more efficient to have one larger transformer supplying power to the LCD/DVD/SAT/home theater bundle in the living room (hacking those devices to directly input DC)?
From
Wikipedia - Tranformer, Energy losses:
Quote:
An ideal transformer would have no energy losses, and would be 100% efficient. In practical transformers energy is dissipated in the windings, core, and surrounding structures. Larger transformers are generally more efficient, and those rated for electricity distribution usually perform better than 98%.
Experimental transformers using superconducting windings achieve efficiencies of 99.85%. While the increase in efficiency is small, when applied to large heavily loaded transformers the annual savings in energy losses are significant.
A small transformer, such as a plug-in "wall wart" power adapter commonly used for low-power consumer electronics devices, may be as low as 20% efficient, with considerable energy loss even when not supplying any power to the device.
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I've looked around for info on the efficiency of the AC-to-DC conversion in typical electronics devices, but no luck. Only some random talk of full-load and no-load efficiencies, windings, cores, eddies, hysteresis, etc. Most efficiency/load charts seem to be for industrial sized, multi-kVA transformers. From tid-bits of information I've pieced together it
appears that some transformers' efficiency increases with load, while for others the maximum is in the 30%-60% load range, after which it decreases.
So the question remains: Several small transformers, or one larger one?