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 Post subject: Practical example of power factor
PostPosted: Wed May 02, 2012 9:02 pm 
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(This doesn't directly involve PC PSUs, but this seems the most reasonable place to post it.)

I've been using a borrowed Adcom GFA-555 for a couple weeks & watching it through my Kill-a-Watt. This amp has a pretty sizable power supply, and the KaW has shown some interesting data.

The 555 draws about 45W/70VA idling (a bit more when it's hot). But it sucks a lot more to charge its capacitors when first powered up. I've seen this hit between 275-375W; it's very inconsistent because the KaW samples too slowly. Tonight I looked at power-on VA for the first time. 830! The power factor goes way out of whack with that 1st second's hugely capacitive load.


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 Post subject: Re: Practical example of power factor
PostPosted: Sat May 05, 2012 11:09 am 
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I just googled for some pics of the inside of that amp, and not only does it have large capacitors, but it also has a large toroidal transformer, which means the inrush current will be even higher. The power factor can't really be 830 though; it is by definition between 0 and 1.

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 Post subject: Re: Practical example of power factor
PostPosted: Sat May 05, 2012 4:07 pm 
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I read it as 830VA....not a power factor of 830.

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 Post subject: Re: Practical example of power factor
PostPosted: Tue May 08, 2012 10:23 am 
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Yes, it's 830VA at 300ishW, so power factor is well below 0.5.

The 555 has 60KuF at 80V. It's a fair bit of energy!


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 Post subject: Re: Practical example of power factor
PostPosted: Tue May 08, 2012 11:43 am 
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Now you know why lights flicker when a big amp is is turned on. :shock:

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 Post subject: Re: Practical example of power factor
PostPosted: Tue May 08, 2012 12:27 pm 
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Either that, or someone is getting it in the Big House.

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