Bill,
Power factor correction is an area I am a bit hazy on. Could someone explain
why the power factor would be different between a direct-rectified PS and a
transformer-isolated one?
I have mentioned it before, but I can explain it again: Yes, both charge
the capacitor with pulses, so the difference between the two is not very
large. But when there is a transformer, this transformer places both
resistance and inductance in series with the circuit, moderating the
intensity of the pulses, stretching them out, and even getting them a
little closer to the correct phase.
Note that the transformer does this through its imperfections: Winding
resistance, and leakage inductance. The better a transformer is, the
worse the power factor gets! A power supply using a perfect transformer
would have the same power factor as a direct, transformerless one. In
reverse, a transformerless power supply's power factor can be improved
by deliberatingly adding series inductance and resistance.
Manfred
========================
Visit my hobby homepage!
http://ludens.cl
========================
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|