Quote:
Originally Posted by vwdevotee
What's the advantage for a residential customer to have unity PF (other than bragging rights, which is good enough for me)? I know that industrial customers are billed based on some aggregate of their facility PF, but not residential customers. I've heard arguements that active PFC usually decreases the system efficiency because there's another transistor (or FET or OGBT) dissipating power.
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Yes, active PFC will introduce more inefficiencies for precisely those reasons. However, from what I understand, PFC allows the user to draw more power from the wall circuit.
Low PF circuits may have a low average current, but the instantaneous current may be spiking higher or near the rated current for the breaker. Hence, you may be only to use half the power of a given outlet before the breaker trips. Not too much of an issue if you're on a 240V 30A outlet, but more of an issue if you're using a 120V 20A outlet and want to charge in a reasonable amount of time.
Another advantage would be plugging into 120V or 240V without having to change any settings on the charger (maybe output current, if there's not an input current sensor)
Stepping back from the trees, there's also the perspective from your electricity provider. From wikipedia:
"The significance of power factor lies in the fact that utility companies supply customers with volt-amperes, but bill them for watts. Power factors below 1.0 require a utility to generate more than the minimum volt-amperes necessary to supply the real power (watts). This increases generation and transmission costs. For example, if the load power factor were as low as 0.7, the apparent power would be 1.4 times the real power used by the load. Line current in the circuit would also be 1.4 times the current required at 1.0 power factor, so the losses in the circuit would be doubled (since they are proportional to the square of the current). Alternatively all components of the system such as generators, conductors, transformers, and switchgear would be increased in size (and cost) to carry the extra current."