| Electronics > Beginners |
| nobody talking about switching PS wasting power on input filter caps? |
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| radiolistener:
--- Quote from: Ice-Tea on August 26, 2019, 11:34:49 am ---I'm curious.. how exactly are you paying for it? --- End quote --- All expenses are included in the price. If your equipment has good power factor, the price for kVA will be included in the price for active kWh, the same as other expenses. This is what happens for usual private person with low power consumption. But if your equipment has bad power factor it requires an increase in the generation and transmission capacity of the electric utility to handle the reactive power component. If reactive power component is high enough then you will be charged for each kVA separately. Your equipment don't consume this energy, it just get it and then put back, but electricity company has additional expenses due to reactive power in your equipment (for exampel higher energy loss in transmission line due to heat), so they will include their expenses in your bill. If you're private person with low power consumption, it will be included in price for kWh. If you own some factory which has high power consumption, you will be charged for reactive power separately. |
| stefon:
OK... now I understand power is lost only because of impedance in lines and ac source. Can anybody just give more or less how much is lost for example 1uF conencted on home power, because have no idea what is typical "power outlet" impedance... |
| Circlotron:
Never bothered measuring, but if you have 240V available and you plug in your fan heater that pulls 10 amps the voltage might drop to 235V. This 5 volts drop for 10 amps = 0.5 ohms power outlet impedance. Might be more, might be less in any particular case. 1uF has a reactance of 3183 ohms at 50Hz so it would pull 0.0754 amps at 240V so the I2R losses in 0.5 ohms would be about 0.00284 watts. 2.8 milliwatts. Not a lot in the big scheme of things. |
| Simon:
I think power companies will accept a minimum of power factor and after that start charging. Most large devices are now controlled by legislation about power factor. Also, the energy companies are supplying the whole grid, not just you so you capacitance will cancel someone else's inductance if they are close enough that the wiring between you is negligible. If they want to charge me for reactive power they better pay me for reactive power too as I am also a generator. Currently, I am supplying at a power factor of 1. |
| Ysjoelfir:
--- Quote from: stefon on August 28, 2019, 06:06:33 am ---OK... now I understand power is lost only because of impedance in lines and ac source. Can anybody just give more or less how much is lost for example 1uF conencted on home power, because have no idea what is typical "power outlet" impedance... --- End quote --- The typical impedance of the power grid is specified in IEC61000-3-3 with 0.24 ohms + j0.15 ohms. |
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