Increasing transformer efficiency

[Piwoslaw]

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:

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.

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?

[Daox]

Well, since everything is designed to use AC, you'd have to hack every single item to run off DC. Even then, you don't know what voltage its running inside it, or it might be running multiple voltages...

I think that with modern devices and the emphasis on power saving features that has come about in more recent years, things are definitely getting a lot better.

[NiHaoMike]

In general, one large power supply is more efficient than several smaller ones. In addition, in a network environment, you then get additional losses converting AC to DC then back to AC in the UPS.

One of my current projects is the "Allie Moore IPS-35A15V", a high efficiency power supply for my home network. It will supply 12-15V (programmable by a BMS or PMS) at up to 35A to float charge a 12V battery and operate loads. Most home networking equipment use 12V so they can simply be connected to the 12V bus. Other devices use DC/DC converters. (I also plan to develop the "Allie Moore ATX-400DC12V", a 12V DC input ATX power supply.)

[Clev]

Originally Posted by Piwoslaw

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:


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?

Most electronics nowadays use switching power supplies instead of transformers. They're far more efficient, and can handle a wide range of AC (and sometimes DC) voltages.

Combining power supplies makes sense in a single area where multiple devices reside (as in NiHaoMike's example), but higher voltage moves with less loss over the same wires, so it's more lossy to run, say, 12V all over the house than it is to have individual power supplies tapping off 120V or 240V.

[Servicetech]

Originally Posted by Clev

Most electronics nowadays use switching power supplies instead of transformers. They're far more efficient, and can handle a wide range of AC (and sometimes DC) voltages.

Combining power supplies makes sense in a single area where multiple devices reside (as in NiHaoMike's example), but higher voltage moves with less loss over the same wires, so it's more lossy to run, say, 12V all over the house than it is to have individual power supplies tapping off 120V or 240V.

AV recievers are now starting to use SMPS, they are one of the last "holdouts". Furnace transformers are still the old school style, I don't know if they will ever go SMPS.