recently there was this door to door salesman who tried to sell me a device that supposedly reduces my electricity bill, like a battery or something. he did a demonstration and it appears to work, according to his handheld meter.
i didn’t like him however, so i turned down his exclusive, one time offer and tried to look up the device on the net instead. turns out the product’s website looks iffy, and is in fact incomplete.
i’d like to know more about the product since my electricity bill is pretty high. what are the things called? do they work? is it some sort of scam?
Sales talk or no, you still can’t get something for nothing. Once an electrical appliance is designed and built (and bought) there is no way to reduce the power input for a given output or the energy consumed.
Most such devices merely reduce the reactive line current thus giving the appearance of saving power but they don’t. The current that they reduce is ignored by your electric meter and doesn’t cost you anything other than the energy lost by that reactive current in the wiring resistance.
If you undersood that latter bit, great. if you didn’t just take my word for it and save your money for something else. If you want to reduce you electric bill, use flourescent bulbs and turn them off when not in use. Buy efficient appliances. In other words, follow the advice you can get from you utility on how to reduce your energy use.
Total bullshit. A power factor of 0.77 does not mean that for every 100 watts, or watt hours, you pay for you only get the benefit of 77.
What is delivered to your meter is volt-amperes which is the product of voltage times current. Volt-amperes is made up of two parts, watts and reactive volt-amperes. Your electric meter responds only to the watts and disregards the reactive volt-amperes.
I should mention that the utility wants a unity power factor to reduce line losses. The line losses are proportional to the square of the line current and unity power factor gives the least current in the line. Utilities like unity power factor so much that they go to the trouble of hanging capacitors all over their system to get as close to unity as possible.
If you install a PFC device at your home’s breaker panel, the only one who will benefit will be the power company. Why? Because the device will make the impedance of your home - which has a resistive & reactive component - “look” like a purely resistive load (or very close to it) from the perspective of the power company. The power company likes this, since it means it won’t have to pay for the I[sup]2[/sup]R loss in the power lines that are created by the reactive component in your house.
Now… if a PFC device is installed somewhere in your house at the load, it does have some benefit to you (in addition to the power company), since there will be less I[sup]2[/sup]R loss in your home’s wiring (which you would otherwise pay for). But for most loads, the benefit will be so small that it’s probably not worth it.
Suffice to say, it’s basically a scam. At least for home owners.
Even industrial users who benefit from power factor correction don’t benefit much from the reduction in wiring losses within their plant. The benefit is that the power company gives them a cheaper rate. In effect the power company shares some of the savings in their line loss with the customer.
i see. his meter was measuring something my electric meter ignores… thanks for the replies.
so basically they’re legally selling something completely useless without fear of repercussions? the thing isn’t even pretty enough to be a paperweight. =\