Power Saving Devices - Do they actually work?

[Oznog]

Ah, those were sold under the name "GreenPlugs" and the more heavily marketed "PowerPlanner". Home Depot had a TV replaying the PowerPlanner infomercial over and over in an endless loop, it was most annoyingly burned into my mind by force and I have to hate them for this crap.

They not only do a form of power factor correction, but their advertising seemed to show some sort of scope wave indicated the peak voltage was being lowered. I don't know what's up with that peak voltage reduction, but I'm curious to find out more about that feature. I also saw somewhere that this was used if your power company was sending you an especially "hot" main (say 130v rms) then it would trim down the voltage and lower the excess current in the process. I doubt this is often a useful case.

I have seen the "flea market demonstration" personally. They show a motor with no run capacitor installed, and no load, will see the absolute (real+imaginary) current go way down. This is totally irrelevant because with no load no real current is being used, it's all reactive. The motor is not doing any useful work. Home Depot had a similar demonstration box set up.

I don't believe power companies can charge for reactive power (aka "imaginary" power). It is not energy and I don't think the meters read it. I kinda want to do some research to be sure. Anywasy, power factor correction eliminates the reactive component.

So here's the jist. Motors such as a fridge, AC, etc usually have a "run capacitor" in parallel with the motor to cancel out its reactive current anyways, an effective form of power factor correction. Some power tools do not, I think not only because the tool size is important but the required capacitance varies with load and the load is unpredictable. Plus it's probably just not important given the intermittent use.

I read somewhere that the type of circuit used by these was integrated into all finished appliances made after 1992. Simply put, it is implausible that anything simple which could save even 1% off your energy would not already be built into a significant device like an AC system.

At best, this will save you nothing unless it's on a pre-1992 appliance, at worst, the noise induced from mucking with the waveform might hurt the motor or electronics inside your appliance. This waveform goes to the electronics and its SCRs, etc and unexpected waveform features could toast some systems.

 

[indecided]

Oh, I did forget to add.. There have been ill effects.

Such as the "switch-off-thump" of various switches (lights, fans etc) have become evident in my speaker setup... how sad.

I run two kitchen fridges, two commercial chest freezers, 3 active (6 present) air conditioning units, of which all are newer then 1992. To be exact, about 1996.

Well, I guess the only way to see is to wait for the electricity bill this month, it's never off by about +-5%.

 

[eblc1388]

Phasor, do you think you could address this?

A friend of mine saw the following setup/demonstration and he was pretty convinced that can not be right. However, he could not figure out how.

If you know how this is done, he would be happy.

Power(AC) is connect via an energy meter(W), one with a rotating disc visible, to two power sockets(S1 & S2) in the following fashion.

AC-->W-->S1-->S2

When an appliance is plugged into the first socket(S1), the energy meter disc starts rotating quickly.

Now the "energy saving" device is plugged into the socket S2, the rotating speed of the disc is visually observed to be slowed down. If the device is removed, the disc speeds up.

As the energy meter measure power, the device thus was shown to save power via the demonstration.

By this time a large crowd had gathered and one of them who is an electrical technician said, "I don't believe you a bit. Your energy meter must be doggy."

The demonstrator replied, "Provide me with your own then. If the disc does not slow down as before, I will pay you the cost of the meter plus $100."

Certain that the energy meter is rigged, the technician brought his own. He ended up buying the device from the demonstrator.

L.Chung

 

[eblc1388]

Certain that the energy meter is rigged, the technician brought his own. He ended up buying the device from the demonstrator.

When the technician was walking home, suddenly he got an idea and he quickly returned back to the stand where the demonstrator was still there.

Technician said to demonstrator, "Does your device works in any socket inside the house? Can you show me it does by putting the device in socket S1 and the appliance in socket S2?"

The demonstrator replied, "Of course I can but I don't want to. If I place the device in S1 and the appliance in S2, all the clever people around here can say my device somehow reduce the voltage or current to S2 by some means and this would ruin the creditability of its magic function. Nobody can say that if I place the device in socket S2. In addition, Sir, one reminder, on the device you have bought, the LED on it will flash when you first plug it into the main because it is learning the power profile of all your household appliance. When it stop flashing, it will then configure itself to reduce your power bill in the most efficient way."

Thought about the argument for a brief moment, the technician agreed it is very logical and so went home happily.

 

[eblc1388]

By now our technican had already gone home and have had his dinner and a nice long hot bath. Of course the first thing he did when he reached home was to plug the device in. As expected the LED start flashing and kept on flashing....

Then he suddenly realised that he had forgotten to ask the demonstrator for how long the "learning mode" would be. He said to himself perhaps he would do that when he is return home after work the next day. As all of you would have guessed, the stand and the demonstrator had gone.

When he returned home, the LED is still flashing, flashing....

He thought to himself, perhaps it will stop flashing tomorrow.

 

[eblc1388]

The next morning, the LED on the device was still flashing. Our technician was furious and decided to take the device apart. He was in for a nasty shock.

There were only 5 discrete components inside the device and he knew every one of them. He saw a 0.1uF capacitor, a zener diode, a bridge rectifier, a small electrolytic capacitor and a LED. The device he had paid good money for is nothing high tech but a simple main operated LED flasher, obviously without any transistor, the LED must be of the self flashing type.

By now he was 100% sure he had been conned but the big question is how?

He retraced carefully every scene happened that evening where he was at the stand with the demonstrator.

1. The Wattmeter (energy meter) is good because its mine.

2. I plugged in the device myself while both hands of the demonstrator is in my clear view so that he could not have possibly throw a switch or doing something doggy with his hands.

3. There even was an analog voltmeter showing me that the input voltage always remains the same during the whole time. Its pointer hardly moves at all.

:evil:

Damn, the guy used a meter with a stuck pointer and changed the input voltage when I plugged the device in. He must had done that with a foot switch.

Satisfied that he had found out the true reason how he been conned, our technician carry on with his normal work.

That night, he had the strangest dream in which he again visited the same stand but this time the demonstrator was not there. Wasting no time he removed the two fixing screws of the socket S2 and looked inside.

Two wires which came from socket S1 were connected correctly to the "L" and "N" terminal. But wait, why is there a big diode connected across "L" and "N" and two wires across the diode going to a small normally closed microswitch installed under the earth pin. Judging from the position of the microswitch, any thing fitted with an earth pin, when plugged in, would actuate the switch and cause the switch to become open-circuited. Why on earth would someone wire a socket this way? It does not make sense. Before he had time to contemplate an answer, the dream ended and he woke up with a cold sweat.

Sadly our technician story ends here and till this date no one have ever solved the mystery of the above case.

 

[eblc1388]

Power Saving devices - Do they actually work ?

Final thoughts:

I realised that the subject of this thread is "Power Saving devices, do they actually work? "

Well, I don't know.

My previous posts made no intention to answer such question because there are hundreds of technolgy and technique used with different brand of "energy saver" available for sale. Many of these device might actually save you energy as claimed. I had made absolutely no effort to recommend or discredit all or any such devices.

What was said in the posts was any device, including a brand new plug, would appear to act as an energy saving device if given a "suitable" environment.

 

[bonxer]

Oh, I did forget to add.. There have been ill effects.
Such as the "switch-off-thump" of various switches (lights, fans etc) have become evident in my speaker setup... how sad.

Switch-off-thump! I experience this 'crack' in my computer's 4.1 surround sound speakers everytime someone turns off the bathroom light/fan! The power plug on them is two-prong, no earth ground. I have them plugged into the wall through a surge supressor. Is there anything I can do to get rid of that switch-off thump?