I was not complete in my response, my apologies. The latest version of MIL-STD-461E extends the frequency range of CS01 (actually now CS101) to 150 kHz. I ran a sweep with a 50 Ohm signal source and likely an oscilloscope load. This was a very small low power transformer. I don't know if it contained an electrostatic shield. Construction notes of the mil-spec injection transformer makes no mention of an electrostatic shield. The mil-spec says the self resonant frequency shall be greater than 80 kHz at 1 Vrms. That may be the key here, if the self resonant frequency depends on applied potential. Because with test CS01, just a few Volts are applied. And in my sweep test, I would have been running well under 1 Volt.
> From: John Woodgate <[email protected]> > Reply-To: John Woodgate <[email protected]> > Date: Tue, 29 Apr 2003 21:27:05 +0100 > To: [email protected] > Subject: Re: FCC Limits > > > I read in !emc-pstc that Ken Javor <[email protected]> wrote > (in <bad43d9e.1f13%[email protected]>) about 'FCC Limits' on > Tue, 29 Apr 2003: >> At one time I needed to perform MIL-STD-462 power line audio frequency >> susceptibility test CS01, which places the secondary of a transformer in >> series with power to the test sample. The primary side is driven by an >> audio amplifier of low source impedance. In the US, the sole source of the >> mil-spec version of this transformer is Solar Electronics. Before I had one >> of theirs, I just went out and bought a 2:1 step down ratio transformer >> (like the Solar model) that was built just for 60 Hz, and it worked fine in >> my application. So that's why I think a 50/60 Hz transformer built for 230 >> Volts will attenuate input 150 kHz ripple by twice as much as a transformer >> built for 120 Vrms. > > Your experience, even at 20 kHz, is not a good guide to what happens at > 150 kHz and above. Above the frequency at which the primary winding > resonates with its self-capacitance, you no longer have a transformer. > > If a transformer has an inter-winding Faraday screen (of foil, not a > layer of winding), its attenuation of even low radio frequencies is very > high. > -- > Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk > Interested in professional sound reinforcement and distribution? Then go to > http://www.isce.org.uk > PLEASE do NOT copy news posts to me by E-MAIL! > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > Archive is being moved, we will announce when it is back on-line. > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
