You know those little gadgets that purport to reduce how much electricity you’re using? Scams.
Here’s Dan Rutter:
Plenty of people stand ready to take your money for “power saving” gadgets that don’t actually do anything at all. There’s a plague of these bleeding things. Search for “power saver” and you’ll find dozens of them. They usually claim to “stabilise” the mains voltage and reduce “overheating” and/or “power loss”, thereby making all of your appliances more efficient and saving you money. And they’re supposed to protect you from power surges and lightning strikes and, I don’t know, probably tornadoes as well.
If a little thing you plug into your breaker box or an outlet advertises power-saving or bill-reducing properties, it’s snake oil. Reducing your “Power Factor” is meaningless, writes Dan: even if the scam gadgets worked, residences aren’t billed for it and ordinary electricity meters don’t even record it.
Internet washing machines, and magic rip-off boxes [Dan's Data]
I should show these to a coworker who’s specifying a replacement for a burned-out power factor corrector on our telescope’s power line. It’s as big as a car, and not quite big enough!
the only thing that does and would ever work is an auto cutoff switch like the one i have wired up to my desktop, its not rocket science, it just kills power to everything when the CPU is off.
Of the ones I’ve taken apart, I’ve found that these ‘power savers’ are just a spark quenching circuit. A capacitor and a resistor in series mounted across the AC lines. The components cost less than a dollar… You can make ‘em yourself, if you know what you’re doing, of course.
(Um, don’t do this at home folks, the values of the components are critical if you’re connecting these to your AC circuit. You may/will get a fire or an explosion if you do it wrong. Just don’t do it.) (Amateurish fiddling with stuff can be dangerous – just see the article about the kid who was killed by an office chair.)
In any case, spark quenching wouldn’t affect your meter’s reading – unless you’ve got Van der Graaf generator-sized sparks coming of your circuits…
Dan’s got a more complete explanation of power factors here:
http://www.dansdata.com/gz028.htm
However, his assertion elsewhere that a QUALITY 300w PSU is sufficient should be, well, qualified:
As long as the PSU’s outputs are matched to the particuliar machine it’s installed in (that is, the amperage from the +5V, +12V, etc, match your system’s needs). AND if you never ever change that configuration.
Me, I prefer to get a high-quality, efficient 500W (or so) PSU – they’re usually not that much more expensive; it’s the QUALITY part of the specification that makes them more expensive. The extra available amps allow for extra loading: temporary extra drives, fans, etc.
I find I get less or no RFI from better PSUs, and the voltages are rock steady even during the short pulses where the (in a computer they’re all) inductive loads start up.
It’s one place you shouldn’t skimp on when you’re building a computer.
“The apparent power that comes from a bad power factor is not real power at all. It’s extra current flow, which loads up the distribution network; that’s why electricity companies don’t like lousy power factors. But it is not actual real power, which is why the electricity companies don’t charge you for it.”
Huh? Does that even make sense… The imaginary part of the power you measure is certainly real, why else would the power company charge larger companies for it. I do agree most households are going to have a reasonably good power factor (with something like AC or heatpump being the bigger contributors to bad power factor). These things are crap, but just spouting out that since the power company doesn’t measure that side of power it doesn’t matter isn’t giving people a full picture of the issue.
Power factor is the measure of the phase between the current wave and voltage wave of ac power (pf doesn’t exist in dc). As voltage and current become out of phase the total power over a given period becomes higher. That power has to be transmitted, which is where the loss comes in. If all the power lines were super conductors then fine, but having a more efficient machine reduces the losses in the power line and components before the substation. Adding this up to hundred of houses does add up.
It’s not really something a consumer should be focused on, but it’s something that utilities and governments should make aware to the product developers…
Ack. Ack ack ACK. I can only hope some people read this to undo some of the damage done above.
For the first poster, who took away from this that his coworker replacing a PF correction unit the size of a car is doing pointless work: if a PF correction unit that large was in place, it’s because it was necessary. Your telescope probably uses stupid large inductive motors to move, and that means it wreaks havoc on the local PF (pushing it down below .8 is not unlikely), and the local power co probably DOES charge you for that.
Fourth poster: the imaginary power is NOT real- hence the term “imaginary”. What IS real is the line loss caused by the increase in current- that’s what the company charges for. That, and the work they have to put into rebalancing the load to provide a good PF to everyone.
Power factor correction is like 17th century waste disposal: sure, you COULD just dump your chamber pot out the window, but it’s rude. Likewise, PF correction isn’t needed for home consumers, because they won’t charge for it, but having some knowledge of it (at least if you use a lot of electricity) is good- and taking away a single talking point (PF correction is bunk) from an article like this is BAD BAD BAD.
Are devices like the one above useful to a consumer? No. Is PF correction a real issue and something that must be considered by any manufacturer designing consumer products? Absolutely.
@5: I think you misread #1. Imagine a smiley or two, if it helps.
I was just starting to investigate these devices before I quit my HVAC techician job. We were considering installing some of these on systems with some data loggers to see what they actually did. In the salesman’s presentation (he wanted us to be a dealer) he had a power meter like the kind on your electrical panel hooked up to a typical furnace motor. When the power factor correction device was hooked up the motor actually pulled less amps and the power meter spun slower while the motor seemed to have no drop in performance. Not being an electrical engineer I tried to have him explain it to me in plain terms. The best explanation I got is that the device cleans up the “static” in the sign wave of the power and stores any “peaks” which it turns into usable electrical power. My understanding is that it primarily helps with loads on motors as opposed to other household loads. The best explanation I have found has been on wikipedia (look up power factor correction). The dirty little secret that I got from the salesman and from wikipedia as quoted by wikipedia: “The significance of power factor lies in the fact that utility companies supply customers with volt-amperes, but bill them for watts”. Simply put, the devices seem to reduce the the amount of watts that the power meter registers and thus saves the consumer $$$. I have asked many people (including engineers) about these and typically their eyes glaze over. If anybody out there is smarter than me, please tell me if I am being sold a bill of goods. I havent spent any money on these yet but would love to get my hands on one to play with.
Uhm. I have read about Phantom loads. And all you need to do about that is remember to unplug you appliances when you don’t use them. You can make the act of unplugging more streamlined and quick with a simple extension cord with a power switch.
I have always unplugged my computer, TV, videogame and DVD-player at night, can’t sleep with that electrical hum or those led lights that indicate power connection. It wasn’t until recently that I learned that this probably has saved me (well, ok, my parents) a bunch of money on electric bills…
This isn’t the same thing, though, is it?
I’m a power engineer working on a power factor correction project for a large industrial facility. I am doing some internet research and just happened across this site.
Power factor is a difficult concept, even for many engineers. (I had a professor in college who had sent satellites into space, and he candidly admitted that power factor baffled him.)
Here’s an easy analogy:
Think of a bag of potato chips.
You open the bag and it just doesn’t seem full enough.
Then you look at the label and it says it’s packaged by weight, not by volume.
Yes you only eat the chips, but you’re charged for the air as well. The extra air in the bag is not a scam. It’s just an unavoidable and normal part of packaging and delivery.
The ratio of weight to volume would be like “power factor” of packaging and delivery.
Utility power is like that bag of potato chips.
“Real” power (watts) is like the chips. Real power is the only power your motor (or fridge, or hair dryer, or TV, or light fixture…) can “eat.”
The “imaginary” or “reactive” power is just “air” in the wires, an unavoidable part of what it takes to deliver the watts.
Plugging something into a receptacle to reduce power factor is like “vacuum packing” the bag. You get more “chips” (watts) in the same size “bag” (volt-amps).
The most common device for “vacuum packing” power is a capacitor.
The most common thing that blows more air into the bag is a motor.
So connecting a capacitor in parallel with a motor helps deliver more chips per bag (watts per volt-amp) to that motor.
A well-designed capacitor-resistor device plugged into the wall will indeed “vacuum pack” your power, but at the residential level you might not even notice it. If you use one, buy a good one. Put one on each motor and inductive load (fridge, washer, dryer, stove, air conditioner). You probably won’t be able to measure the difference though because the utility sells power to residences only by the “bag.” You’ll have to do “before” and “after” comparisons of your bills to figure it out.
Be mindful though- A really cheap device may truly be a scam, and the power savings are so low that you wouldn’t be able to prove it.
Industrial facilities are different. They use so much power that they have special “bulk” contracts with electrical utilities. Factories buy power by the “truckload,” not by the “bag.”
Factories are full of motors, which may blow too much electrical “air” back into the utility system. This is a bad thing, so the utility charges more for this (low power factor).
The factory can save money by increasing power factor, typically by connecting giant capacitors across the utility transformers. In a case like this, a capacitor as big as a car is very rational.
Now “phantom power” is a totally different thing. Phantom power is that power trickle that a device uses when you think you’ve turned it off. A good example of phantom power is the clock on your cookstove. Yes you turned off the range, but the clock still draws just a trickle of power. Normally this isn’t an issue, unless you are supplied by solar panels or batteries, where every electron counts.
I just installed a power factor correction in my home. I purchased the largest single phase unit they had. It increased my power factor from .851 to .983. It reduced the power consumption by a little more than 15%. It will take a year for my pay back. But I will also suffer less damage from surges, etc. The lights no longer momentarily dim when the air-conditioning compressors come on. We live in Oklahoma and use a lot of cooling. The savings will not be as great in the winter, when we use natural gas.
/s/ Tom Milam, Jr.
milam@inglesrud.com
I worked for 20 years in the Air Force in the power generation field. Power Plants, Mobile generators. We dealt with cross currents and reactive loads all the time. Think of the wires that go to a large motor as being electromagnetics. When there is too much cross currents (bad power factoring) The motor works harder and tends to heat up more and thus uses more power. The motor wears out quicker. The power factoring units saves you money by conditioning the line with cleaner electricity. This was true when working in a multi generator facility. Bad power factoring would have a operator running around the the control room trying to insure that all the running generators had a balance load. Most new power plants have to some degree have a automatic power factoring system in place. So using the power factoring units for line conditioning is a great idea. a power factor meter connected into the breaker panel to see if there is bad power factoring going on would be a great idea. As for the meters on the house. The meters are current use meters. Voltage is measured as a reference for calculating watts used. Lets say that a water well pump has a working voltage of 90 to 130 volts A/C. If the tries to start and the voltage is 90 volts, then the motor will use more amps to start. More amps used. more money cost. I hope this helps
Funny,
As an energy auditor, I had the same skeptical view until I saw the savings over and over in all kinds of applications, so all I can say is the good ones work, and I would say get over your skepticism and try one for yourself. I have been recommending them for two years and have not had one case of non performance. Skeptic no longer, and no, I don’t sell them for you skeptics. lol