Understand what is being said, and it is valid for the input filter before the bridge, but some SMPS can have caps on the DC bus or DC return which are effected by both the PFC and main converter stuff. This is not always 100Hz sinusoidal stuff.
The other problems with many PFC controllers is that they cannot get as close to unity at 100V as they can at 240V. So 'noise' current through ground wire can be significantly different for same loading conditions at different input V. Capacitive coupling from h/s to ground can be significant, but the better designs mitigate this so not a dominant effect. Much of the 'ground' noise can be stuff that is radiated from the main converter's power loop directly into a primary trace or other component that is somehow coupled to ground. When I become emperor, only flyback converters without PFC will be allowed. There will be much noise and we will like it... Brian -----Original Message----- From: John Woodgate [mailto:[email protected]] Sent: Thursday, July 23, 2015 2:25 PM To: [email protected] Subject: Re: [PSES] GFCI Nuisance Tripping In message <blupr02mb1169506aba5d6abb9e7b9e3c1...@blupr02mb116.namprd02.prod.outlook .com>, dated Thu, 23 Jul 2015, Brian Oconnell <[email protected]> writes: >No. And is dependent on converter topology and operating conditions and >whims of the Klingon High Command. Since the supply current is (nearly) sinusoidal, I suppose that the leakage current through the 'hot' Y-cap is sinusoidal, but the current due to the capacitance to ground of the switching device's heat sink (and maybe other parts) is not sinusoidal and may not be negligible. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
