[time-nuts] HP and other equipment failure

[J. L. Trantham]

Thanks.  Now it makes sense.

Sorry for the interruption.

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Azelio Boriani
Sent: Saturday, June 15, 2013 4:58 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] HP and other equipment failure

Although off-topic here, the PFC (or power factor correction) is a switching
mode front-end used to correct the cos-phi of the otherwise capacitive load
that every switching mode power supply is for the mains.

On Sat, Jun 15, 2013 at 11:52 PM, J. L. Trantham <jltran at att.net> wrote:
> Sorry for the interruption but what is 'PFC'?
>
> Thanks.
>
> Joe
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] 
> On Behalf Of Poul-Henning Kamp
> Sent: Saturday, June 15, 2013 4:09 PM
> To: Robert Atkinson; Discussion of precise time and frequency 
> measurement
> Cc: Perry Sandeen
> Subject: Re: [time-nuts] HP and other equipment failure
>
> In message 
> <1371329221.83869.YahooMailNeo at web171902.mail.ir2.yahoo.com>,
> Robert  Atkinson writes:
>
>> While I agree with everything else you say, you CAN have too much 
>> filter capacitance. At least where dc rectifier / filter (smoothing) 
>> circuits are concerned. Increasing C causes increased ripple current 
>> [...]
>
> And ripple current can be a major source of power-line frequency noise 
> in all electronics.
>
> The main reason why switchmode power-supplies today (can) outperform 
> linear power supplies with respect to noise, is because the legally 
> mandated PFC correction eliminates the bridge-rectifier ripple harmonics.
>
> I would not hessitate to use a good quality switchmode to replace the 
> linear supply in a HP5370B.
>
> I did some experiments a couple of years ago, with an audio-amplifier:
> I put a standard PFC corrector chip on the secondary side of the trafo.
>
> The overall result was not satisfactory, but the 50 Hz "sneer"
> we all know and hate was absent, and the "Tzoing!!!!!" power-on 
> mechanical shock from the trafo was also eliminated, as was the 
> consequent dimming of the lights ;-)
>
> The main reason not to do this, is that you need some physically 
> gargantuan coils for a 10A+ PFC-switcher.
>
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by
incompetence.
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