[time-nuts] HP and other equipment failure

[Max Robinson]

I don't know what's more incredible, that people sell that stuff or that 
people buy it.

Regards.

Max.  K 4 O DS.

Email: max at maxsmusicplace.com

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----- Original Message ----- 
From: "Peter Gottlieb" <nerd at verizon.net>
To: <time-nuts at febo.com>
Sent: Monday, June 17, 2013 7:33 AM
Subject: Re: [time-nuts] HP and other equipment failure


> The current distortion from simple transformer-rectifier-capacitor power 
> supplies contains a lot of third harmonic content.  In a 3 phase system 
> (as are all distribution systems for commercial and industrial) the third 
> harmonic ADDS in the neutral, or creates circulating currents in a delta 
> configuration.  These currents, as you mention, can get very large and 
> were the cause of many transformer explosions in cities as these power 
> supplies became common.  The transformer designs had to be improved, but 
> the PFC supplies make a big difference.
>
> How many of you have looked at the power line waveform, especially in an 
> industrial or commercial area?  Doesn't look much like a sine wave, does 
> it?  So it's pretty funny to see audiophile outlets 
> (http://www.dedicatedaudio.com/power_outlets).
>
> Peter
>
>
>
>
> On 6/15/2013 6:56 PM, stan, W1LE wrote:
>> PFC to me is power factor correction, not only the classical power factor 
>> to minimize (VAR) volt-amp reactive component,
>>  but also to remove the harmonic load  current imposd on the electrical 
>> power system.
>> A '90's onward technique. in th 80's and 90's without the harmonic load 
>> current reduction and having
>>  a few 100 end items of equipment, each withtheir own  a switch mode 
>> power supplly,
>>  it was not uncommon to find hundreds of amps of the third harmonc on 
>> neutra,
>>   in the electrical power distribution system.
>>
>> Could be a serious EMC problem if you were dealing with voice grade 
>> channels.
>> And people safety issues.
>>
>> Stan, W1LE   Cape Cod
>>
>>
>>
>> On 15-Jun-13 5:52 PM, J. L. Trantham 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.
>>>
>>>
>>
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>
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