On 06/15/2015 07:19 AM, Carlos E. R. wrote:
So what they do is penalize customers which do not compensate their power factor to close to one. But, if there is no penalization (and at homes they don't install equipment to measure the power factor (or reactive power)), I don't see the gain in money to the small client.
Maybe I'm missing something obvious... :-?
There are many good articles on the 'Net about this, but here's the simplest analogy I can think of that draws the difference between kW and kVA. Think in terms of force vectors, a boat or a plane or more simply dragging a block. The rope goes over your shoulder so the force vector is not horizontal, even though you are trying to drag the block horizontally. Electric motors, for example, work by creating magnetic fields which produce a back emf, in opposition to the applied voltage. This causes the supply current to lag the applied voltage. The resulting out of phase current component cannot deliver usable power, yet it adds to the required supply and hence costs. As discussed earlier in this thread, fitting capacitors across motors reduces the phase lag and improves their power factor. In the limiting case where the phase lag is 90 degrees there is no work being done. Power factor = cosine(90) = 0 so Volts X Amps X Power Factor = 0 even though Volts X Amps is non zero. So the power factor tells how much more power is needed to do the 'rated' work of the machine. More power, bigger bills. As I understand it, this also affects the power distribution grid, hence network costs increase as well. Again, googling will show sites that do calculation on how much you can save. When I looked into this at the time I found that this was serious business; there are many industries that run powerful electrical motors and hence there is a market for pretty huge capacitor banks. I also found that the power network have huge capacitor banks at some substations! Some authorities raise the point 'where does this power go?'. Good question. Maybe heat? IsquaredR losses still apply. In fact to get the same power, more current has to be drawn since voltage is a constant. Other think it produces some kind of electrical back-pressure on the generator. Certainly the utility company can tell if you are running with an abnormal load factor. How does this relate to us? See https://en.wikipedia.org/wiki/Switched-mode_power_supply#Power_factor for a start. All of our desktop PCs and many rackmount systems use switched mode power. Most of my equipment is "EnergyStar" rated. https://en.wikipedia.org/wiki/Energy_Star Not just computer equipment but my refrigerator and lighting, HVAC, washer/dryer. All of these are devices which alter the 'load factor' and need correction. -- A: Yes. > Q: Are you sure? >> A: Because it reverses the logical flow of conversation. >>> Q: Why is top posting frowned upon? -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org