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Old 30th June 2007, 02:33 PM   #1
daly41k is offline daly41k  United States
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Default Power Factor correction

After searching through the threads I was wondering if anyone has expeirmented with Pf correction on the primary side of the transformer on any of the Pass class A designs and if it made any difference. I recently have under proding from Grey put together a noise and dc blocking filter for my Alephs for installation on the primary side of the transformer. Now when the weather gets bad I will install it. However, I was reading about the Halcros's and their built in PS that uses PF correction. This means I believe that the phase of the ac current vs voltage is close at all times. I think that is a PF of .95.

In industry using higher voltage three phase power, a set of capacitor banks is put in to keep the pf to the utilities recomendations. I have noticed in class D amps with switching PS designs that PF correction is mentioned.

My question is that for class A pass designs where the current draw from the ac supply is nearly constant wether PF correction offers any benefits. I have not seen anything referencing this using traditional designs in the threads.

I have seen some mention in the aftermarket activve noise reduction units but mostly those offer isolation transformers for low power equipmnent.

I am not sure that for single phase power putting PF caps on the primary side would be worth the hazzle but I am looking for ways to quiet transformer noise. Just musings for now, I will be consulting the text books but I am just checking here to see if this was discussed in the past. dave
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Old 30th June 2007, 03:21 PM   #2
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Any normal rectifier + caps linear power supply will suffer from a poor PF regardless of the load.
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Old 30th June 2007, 09:22 PM   #3
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Quote:
I recently have under proding from Grey put together a noise and dc blocking filter for my Alephs for installation on the primary side of the transformer
I'd like to see that -- I seem to have some nasty noise in me mains wiring. If my rebuilt BZLS doesn't get rid of the noise, I will be looking for other alternatives......


JJ
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Old 30th June 2007, 09:27 PM   #4
Magura is offline Magura  Denmark
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I have asked around in the power buisness, and they all answered that it was not going to make any difference in the scale we are running things. PF correction is according to them intended for loads of 25+ kW motors and the like.

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Old 30th June 2007, 11:28 PM   #5
flg is online now flg  United States
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Some other info to think about regarding Power Factor. We basically have a sine wave at "some level" of purity, hence, "some level" of THD+N may be present on the incoming mains already. When measuring Power Factor, you are measuring the THD created by your device loading down the mains sinewave into a distorted sinewave. You get a resultant of harmonics your load created by it's uneven loading expressed in THD...
When applied to your primary, these harmonics will be causing unexpected voltage changes in the transformers characteristics, coupling, etc. Won't they?
That being said, I'm not sure all of this is in a frequency range that is not easy to control with the typical filtering techniques and simple regulators???
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