[time-nuts] HP and other equipment failure
jfor at quikus.com
Mon Jun 17 12:43:28 EDT 2013
An Audiophool and his money are soon parted.
> 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
> in the neutral, or creates circulating currents in a delta configuration.
> currents, as you mention, can get very large and were the cause of many
> transformer explosions in cities as these power supplies became common.
> transformer designs had to be improved, but the PFC supplies make a big
> 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
> 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
>> 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
>> it was not uncommon to find hundreds of amps of the third harmonc on
>> in the electrical power distribution system.
>> Could be a serious EMC problem if you were dealing with voice grade
>> 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'?
>>> -----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
>>> 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
>>> all electronics.
>>> The main reason why switchmode power-supplies today (can) outperform
>>> power supplies with respect to noise, is because the legally mandated
>>> correction eliminates the bridge-rectifier ripple harmonics.
>>> I would not hessitate to use a good quality switchmode to replace the
>>> 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
>>> shock from the trafo was also eliminated, as was the consequent dimming
>>> the lights ;-)
>>> The main reason not to do this, is that you need some physically
>>> coils for a 10A+ PFC-switcher.
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