EBME Forums Forums Maintenance Technical Assistance Power Perfector

Has any one had any dealings with a powerPerfector?

There is one fitted at Cirencester Hospital, Dudley and other Trusts.

Apparently it is a "Voltage Power Optimiser" which drops the mains voltage supply inside the hospital and hence reduces power consumption by about 8% (they say).

Lee

Have I been labouring under a misapprehension, then, all these years about P=IV x Cos theta?

Won't kit running at reduced input voltage tend to draw more current to get the power it needs?

It must be about Power Factor Correction, I would have thought. Which has, of course, been used in industry since Adam were a Lad.

OK. What are the net savings here? That is, once the cost of installation, maintenance and all the rest has been taken into account.

Something to do with the strident Green Lobby, no doubt. See here for a random smattering of buzz-words.

Here's a thought:- how many megawatts (not to mention ice floes, Polar Bears, or low-lying islands) would we save each year if we binned all the "SATS machines" and went back to using mercury sphygs and thermometers? Yeah!

Meanwhile, I believe I'm right in saying that single phase mains power in the UK has been "harmonised" with Europe at 230 +/- 10% since 2003. That is, nominally 230 VAC, but actually anywhere from 207 to 253 volts. So perhaps that's what is going on here ... installing new transformers (at great expense) to bring the erstwhile 240 volts (which is actually still within the "spec") down to 230.

It's no good going back to mercury sphygs and thermometers. All the available mercury is being used in the low wattage fluorescent lamps!

No hazard there then! Apart, that is, from all the accidents caused during the fumbling about waiting for the darned things to "brighten"!

I looked into this a while ago. There was an article in one of the broadsheets sponsored by a company called VPhase. They reckoned that you could save upto 10% electricity by installing one of their units. I found a Australian "paper" where they debunked the whole thing, if I can find it, I'll put in a link. Essentially the only gain would be in lighting, but if you go for low energy or low voltage lights that would nullify any benefits. The regulations state that the supply should be 230v+10% -6%, the rest of Europe is +/-6% (+10% means that we don't have to alter out voltage from the old 240v). I checked my supply it is about 257v, not sure what I can do about it, don't think the supplier will alter our local transformer.

Yes Bill, you're right:- 230V +10% -6% is the UK spec these days. So that means you're a bit high there, I'm afraid. In fact it would have been out in the days of 240V +/- 6% as well. I can't help but wonder how that came to be the case!

OK ... here's my guess:- you're very close to the 11kV sub-station. Am I right?

Here's the paper I was on about.
Domesic power consumption with varying voltages

Bill

Interesting. Anyone (else) like to comment on the conclusions drawn?

Looking at Bill's paper it would appear that paying 100's of thousands for one of these Powerperfectors would not be very efficient for a typical household type load, I wonder what is the typical loading (split into lighting, heating etc) in a Hospital?

Lee

The VPhase domestic unit costs around £300 but could cost as much again to be professionally (part P regs) fitted. Repayment would take so long you could consider it an inheritance for your kids!