I was recently asked to assess one of the plug-in type"power savers" that are supposed to reduce a domestic consumers electricity bills. Having done a bit of investigation beforehand I thought I would have a simple job proving that it was simply a power factor correction unit and would make no difference to a domestic consumer who is billed only for kWh. I opened the unit beforehand and found that the circuit consisted only of a 20uF capacitor and a resistor (blacked out to hide the value) , which increased my confidence that it would be easy to prove it didn't work as advertised.


HOWEVER - when I hooked up a Fluke 43B meter I found that the kW actually did drop when the unit was switched in - even when a purely resistive load was connected. This took me somewhat by surprise and I can come up with no sound explanation for it other than meter error. I did notice that the current waveform was distorted , particularly with a light load connected. I understand that kW measurement can be inaccurate with a non-sinusoidal waveform but would be interested to hear from anyone who has had experience of this. My theory is that the unit is essentially fooling the meter by distorting the waveform. Obviously an induction meter is different to the Fluke but if it can fool one type of meter chances are it can fool another type.

Furthermore, when lightly loaded the kVA and kVAr readings increased dramatically with a leading power factor - which indicates that far from being "green" the unit actually increases demand on the generating and distribution network.


Regards

Andrew

Hi Andrew,
good luck with your project and sorry I cannot help directly - being thick and that!

However, I was called out to a fault recently where I was boring the client about resistance. He took my head off at 50 paces and told me not to even go there. Turns out this guy is a Professor and bar (physics and nano technology). Nice chap as it happens and has been entertaining chartered status for 50 odd years.

If you're stuck, I'm sure he may be able to put you right although I must warn you, his books retail at £300 a piece and could put you in a coma if you attempt more than a page at a time.

By the way, the said Prof had a go at the fault without joy . I discovered he had a borrowed neutral on his lighting circuit which only manifested its self when a particular light was used. Who needs to be a Professor when you've got NVQ3?

Recent CCU upgrade by a cowboy.

- Wango.

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'They are, in fact, men apart. Every man an emperor'

Field Marshall The Viscount Montgomery

But could he prove or dis-prove the existence of the Higgs-boson?

ahhhhhhhhhhhhhhhh

WRT plug-in type"power savers" which merely consist of what amounts to a one size fits all power factor correction circuit (a bog standard cap) and a couple of LEDs saying "look at me I'm saving power", I think it is about time some of the bods with the power stood up and took a stance on the claims such devices make.

With the one size fits all static PFC units what stops over and under correction and indeed correction where no correction is needed at all. Do these devices contain "Intelligent" capacitors and harmonic filters that can change value on demand.

Unless these units are "matched" to their "I need PFC" loads how do they "save" power?

mmmmmmm

Rant over

Regards

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E & OE

"Turns out this guy is a Professor and bar (physics and nano technology). Nice chap as it happens and has been entertaining chartered status for 50 odd years. "
then
"By the way, the said Prof had a go at the fault without joy"

This can't be right. A degree is required for everything now. He must have had a degree, so he must be able to do everything. I'm just waiting to see the effect a nurse with, say, a degree in the life and times of Mozart, manages to feed me properly in my hour of need.

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Norman