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Hi guy's anybody can give me a brief theory about powersaver the one that i saw in the tv commercial they offer this device to lessen your power consumption is this true ?does anybody try to build this one or any schematics ?
well, this is a bit controversial. it works and it doesnt works. it depends on the application. i am no power electronics guru but i have done some research on this.
i dont know about the one you saw in the commercial but i heard about the one that is for industrial motors. the company claims that their device can save lots of dollars by efficiently driving motors. they say that most of the motors are very inefficient and the ones that are off load for longer periods of time are very inefficient. their device is basically uses a power factor correction algorithm.
such a device works good on motors that are off load for longer periods of time. but most motors work continuously. and in addition to that large industrial motors are very efficient. datasheets of some motors state efficiencies of upto 98% (and thats true to a great extent). so in such a case a power factor corrector wont be of much help.
the only place where such devices work are small industrial motors and the ones that are used in home appliances. those are really inefficient. but the savings made from such small scale industries isnt worthwhile.
so, in a nutshell i would say it depends on your application. if the company offers an evaluation then try it out. and calculate yourself the amount of savings that you make during that evaluation period. dont believe on those commercials and those sales guys, they dont know a thing about electronics :lol:
Power factor correction works by reducing the voltage on the motor so it is running at max load. But since you do not pay extra for poor power factor, what is the point of paying for a correction device?
I would have to agree with the above statements, power factor correction in the average home seems pretty much pointless. Even a home with a 200 Amp service, running at full capacity would have such a small lead/lag in current to voltage that it is neither worth fixing, or charged for anyways.
Believe me, if the power factor of residential supply was a big issue, the utility companies would be all over you or your hydro bill.
I heard that major appliances were required to have similar power correction measures built into them for many many years.
After all, just the run cap- used in all motors- is a power factor correction, though it only provides a fixed reactance and the inductance is somewhat variable.
I saw a "demo" at Home Depot. The device was hooked to a motor with no load at all and no run cap. So of course the load is 100% inductive current and absolutely 0% real current. Well then the power factor correction is turned on and it takes almost no current. Not exactly representative of a real motor usage.
I saw a "demo" at Home Depot. The device was hooked to a motor with no load at all and no run cap. So of course the load is 100% inductive current and absolutely 0% real current. Well then the power factor correction is turned on and it takes almost no current. Not exactly representative of a real motor usage.
yes, thats exactly what these sales guys do. they come to your office (or home) with a small inefficient motor (probably driven with a greater than the required voltage) and they show you a small demo. they run it off load. off-load makes more copper loss and over-voltage makes more iron loss. and then they connect their power saver and voila it works
but these guyz dont know a thing about electronics and if you start asking questions about copper losses, iron losses, windage losses they will probably run away
Power factor correction works by reducing the voltage on the motor so it is running at max load. But since you do not pay extra for poor power factor, what is the point of paying for a correction device?
I would dispute this.
Power-currection does not reduce voltage. It tries to cancel the effect of a reactive load to try and draw Volts and Amps in phase.
Industry is charged per VA, if they draw a lagging (or leading) current they still get charged on VA, but the useful power is reduced, thus it is in their finacial benefit to correct the lag.
Home users are charge per WATT (there is a difference).
As stated no need to to PF-correction in a home, IF you were drawing enough to cause enough to distrupt the power the network at you rlocal substation, then you are close to blowing a fuse, overloading the substation or get a visit from yr local power regulator.
If the device is to actually going to correct a poor Power Factor, I would think that knowledge of the load would be essential. Normally capacitors are added to the line to balance any inductive component of the load. The idea is to create as close to a pure resistive load as possible.
Not knowing the load, which in a residential setting could vary alot, I don't understand how the amount of capacitance could be calculated. I don't think the device is using capacitors anyways, how could they know what size? In a factory you can correct PF at the problem, switching in a known bank of capacitors as needed for a known load.
PF correction in appliances allows the manufacturer to use smaller guage wires, less iron mass, have cooler running motors, less over-all build cost. The lower the VA rating of the load the smaller the wires can be. ( oversimplification, but the general idea )
It all boils down to the old saying ELI the ICE man. E ( voltage ) leads I (current) in an L (inductive) circuit. I ( current ) leads E (voltage) in a C ( capacitive ) circuit.
You can use one to cancel the phase shift of the other.
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