Can you cut down energy consumption by altering the power supply?

04 October 2011


I'm in the process of buying from a company that produces three products for power saving - one is a geyser blanket, one is the geyser timer switch, and one is a thing they called a ‘power saver’ which is the kind of capacitor thing which I understand from my research on the net doesn’t work, but there are lots of people around the world selling these things which people say are a scam. Do you know anything about this?


Chris:: Okay, so just to clarify, you put these things into your electrical supply and in your case, you're saying that you're making geysers or in other words, hot water immersion heater sort of things, and they're supposed to cut down the amount of energy you're consuming in the home. Dave, what do you think?Dave:: There's a couple of ways of doing this - one of them is called 'Power Factor Correction'. This is, if you've got very large motors or sometimes very large electronic loads, you can draw current not at the same time as voltage. So if you imagine alternating current - the current voltage is going up and down, up and down - and if you attach it to a light bulb then it will draw a current at the same time as the voltage, and that's fine - that's actually what the power company wants you to do. But sometimes, if you have these strange loads, they can actually draw lots and lots of current when the voltage is very small, and draw very little when the voltage is very high. That means that because your meter measures a total amount of current (which is flow multiplied by the time) you're apparently using far more energy than you actually are, so you get charged more than you should be, so it can reduce what you're being charged. It also drives the power companies up the wall because it causes havoc with all their systems!Chris:: But moreover, it means that they're doing less for their shareholders than they were before.Dave:: Yeah, I mean, despite the fact that this way you get more power, then they're happier. But that's only a really big issue if you've got lots of big three-phase motors, big motors, or all possibly a very large amount of electronics. But I doubt that's a big issue with houses.Chris:: So Roy's immersion heaters are probably not going to benefit from having one of these things then?Dave:: Certainly not from that. The other way then that some of these things can work is by essentially just reducing the voltage. So it's basically like putting a variable transformer into your system. So, whatever the voltage is coming, it will always put out 220 volts. That means your geysers will actually be less powerful so you'll be able to use less power, but that means you also get less heat.Chris:: You're just going to use it for longer, aren't you?Dave:: But there are some kinds of lighting, especially fluorescent lighting, that are more efficient that way and things like transformers are more efficient that way. So, it'll produce a big reduction in the amount of power you use, but you might get less out of it as well.

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