Intelliworks Energy Saver

Cardew

They do measure kWh, the meter states kWh(not kVa) and you are billed in kWh.

You imagine the outcry if we were charged for kVah while the bill stated kWh

What I understood moonrakerz meant by an assumed power factor, was that in calculating the load(for power factor correction purposes) power generators have to guess the inductive(lagging) load of domestic properties.

Industrial premises can be charged for kVa and indeed 'fined' if their power factor drops too low - so they take measures to keep it as near unity as possible.

This site, although American, is good reading

http://michaelbluejay.com/electricity/powerfactor.html

Amack

Sorry, Cardew. Simply restating that domestic electricity meters measure kWhr doesn't prove the point.

The question is how the electricity meters arrive at the value for kWhr. I'd be interested to get clarification from moonrakerz about what he meant when he said that for domestic customers there is assumed to be a standard power factor. I think that it's quite possible that electricity meters --- or at least the older ones --- actually measure kVA and then apply an assumed power factor to derive a value for kW.

I don't think that there would be an outcry if this was the case. Most people don't have any idea about power factors, phase differences, reactive power, etc., and if the hypothesis in my previous paragraph is correct then the electricity companies are billing by kWhr --- it's just that the kWhr value is based on an assumed power factor rather than a measured one.

Thanks for the reference to Michael Bluejay's site. I've been looking for some reference to actual tests of these domestic power factor devices.

Unfortunately, the test that he has carried out is somewhat flawed. He says that when he did the test he "turned on every light (fluorescents), the window AC units, the microwave oven, and cranked up the refrigerator". The effect -- if any -- of power factor correction is going to be most obvious when the load is largely inductive. Turning on all the lights adds a large resistive load, so the power factor is going to be higher to begin with. Also, fluorescent lights contain capacitors, so they may well be providing an element of power factor correction already. (See my previous submission about how my electricity monitor reading decreased when I switched on a fluorescent light.) So I'm not surprised that that particular test didn't show any effect.

By the way, I agree that the way that the manufacturers of domestic power factor correction devices describe their products does reek of snake oil salesmanship. I don't believe the claim that the devices "actively monitor" the power factor, and the suggestion that the devices can maintain the voltage in the face of a supply interruption is total nonsense.

All that I'm saying is that if the electricity meter measures kWhr by measuring kVA and then using an assumed power factor to derive a value for kW then inserting a capacitance between the live and neutral will reduce the measured kWhr during those periods when the load is largely inductive.

moonrakerz

Amack wrote: »

I've just noticed the above quote in moonrakerz' comment.........
If there is "assumed to be a standard power factor" then that implies that domestic electricity meters are measuring kVA --- not kW --- and then estimating your true power by applying a correction based on an assumed power factor.........
but if moonrakerz' statement is correct then domestic power factor correction does have the potential to be beneficial.

It has always been my assumption that domestic power consumption is measured (in effect) in kVA, then "adjusted" by use of a "standard" power factor (0.8 ??) to give effective kWh. To some extent it doesn't really matter if you are charged per kVA, kWh or per "banana" as long as everyone agrees how a kVA, kWh or banana is arrived at !

That is why I made the statement that it is possible that these devices could make a small difference to actual power consumption, but it is equally likely to be a difference in the "wrong" direction. Then it all goes to pot, if as you say, switching on an additional capacitative or inductive load has an effect as well - which it should do !

The bottom line is that they are "snake oil" !

Cardew

Amack wrote: »

Sorry, Cardew. Simply restating that domestic electricity meters measure kWhr doesn't prove the point..

As in 'repeated assertion ain't proof'!!!

I have seen this subject discussed on several forums - with reference to these PF correction devices which we all agree are a scam.

http://en.wikipedia.org/wiki/Electricity_meter

It surely is valid to state that if the dial on the meter states kWh and not kVa then it is measuring kWh.

My £10 Maplin power measuring meter displays both Watts and volt/amps. so if that can do so, why not a sophisticated domestic meter.

If moonrakerz theory is correct a simple bank of capacitors, or a constantly running over-excited synchronous motor would reduce your electricity bill.

moonrakerz

Cardew wrote: »

It surely is valid to state that if the dial on the meter states kWh and not kVa then it is measuring kWh.

Yes and no. An similar example might be the speed of an aircraft; this might be displayed as mph or knots, but was actually measured as an air pressure.
My car will give me a reasonably accurate mpg figure after a couple of hundred yards (or should that be metres [meters !]) but I have not covered miles or consumed many gallons.

Cardew wrote: »

My £10 Maplin power measuring meter displays both Watts and volt/amps. so if that can do so, why not a sophisticated domestic meter.

Is a domestic meter that sophisticated ? I daresay that modern technology could produce something pretty clever, but the "spinning wheel" has the great advantage of being very, very reliable - although you wouldn't think that by the number of posts on this site where people query their meter reading !

Cardew wrote: »

If moonrakerz theory is correct a simple bank of capacitors, or a constantly running over-excited synchronous motor would reduce your electricity bill.

Perhaps it would (my previous point) but would it be a significant, and constant, amount ?
I wish now I hadn't slept through all those boring lectures years ago about power factors and all the other related garbage !

Amack

Another example is a a scuba diver's depth gauge, which displays depth but is acually measuring pressure and then using an assumed water density to convert that into metres. On the (very rare) occasions when I go scuba diving in fresh water my dive computer actually gives me a slightly incorrect depth indication because it's calibrated for salt water.

Amack

I think that I might be able to test the "bank of capacitors" idea.

My local village hall has several elderly fridges and freezers. These represent almost all the overnight electrical load, which runs at nearly 500W.

I can use my plug-in electricity monitor to check that the fridges and freezers do in fact have low power factors. (Given their ages, I very much doubt that they have built-in power factor correction, but it's best to check.)

Then its a case of finding a safe way to insert some capacitance. I've got some ideas on that, but I'd welcome any suggestions.

If this rough and ready approach to improving the power factor is capable of reducing electricity bills then it should certainly show up in a building using 4 kWhr per 8-hour night ....... and the village hall committee will be pleased!

On the other hand, if using capacitors to improve power factor doesn't produce measurable benefits on a set of elderly fridges and freezers consuming electricity at the rate of half a kilowatt then I think that it's fair to say that it's unlikely to produce any useful benefits in any normal domestic situation.

Does that sound like a reasonable test?

Ben84

I do not see how they can claim that this device saves energy on resistive loads like toasters and water heaters. Their power factor is already 1, and resistance heaters are pretty much 100% efficient at turning electric in to heat. There is no room for improvement of either power factor or efficiency.

Their site says "can reduce at least 10%"

I also consider the statement a conditional positive that when you think about it makes no sense at all. People who don't look too closely will see "reduce at least 10%", which is encouraged by the bold font, but the word "can" completely devalues the meaning of this statement. Why do advertisers never put those little, but very important words like, can, might, possibly and up to in bold.

Let's try "can reduce at least 10%". It's more honest, although I doubt any water heaters or toasters were reduced by 10% in any test with this device.

There is no room to reduce energy waste where there is no energy being wasted.

comicmankev

So they are no good then? Money back guarantee and all??

mstringer

Lots of interesting comment and debate in this thread. Thought I would share some real world observations.

A friend and I recently went about testing this device to see what it could achieve. We connected an eco-eye energy monitor to the mains, this showed a pretty constant energy consumption of 0.56KW.

We then plugged in the Intelliworks Energy Saver to the mains, turned it on and observed the new reading on the eco-eye.

The reading jumped a little to 0.65KW. That represents a net increase of 0.09KW once the device is turned on.

That would appear to me that its actually consuming more electricity than before it was in use!?