My usual caveat - am an EMC amateur. If the transient is propagated in serial fashion then 're-emitted' (as theorized by Mr Woodgate) with similar characteristics as test pulse, do not see how the typical control loop would see the disturbance, other than a resultant OV lock-out. Oscillations on the PFC FET could result if the transient energy were coupled to a hi-z gate drive circuit, but, at least logically, it would seem that the main controller would just lock or skip pulses until the disturbance energy is gone.
Observed this 10 years past during variations of EFT and surge test configurations while playing with floating and ground-referenced mains on an open-frame SMPS, where the chassis could be ground pin-reference or floated. Observed again last year while testing another factory's class II p/s where my GRP was not correctly placed. Response of given model SMPS to ESD/EFT/Surge can vary somewhat, where the difference is the end-use installation. EMC testing of an COMPONENT p/s is problematic and mfr's test data may not be representative of performance in your box. This may become a recurring and noticeable problem as SMPS go to higher switching frequencies to increase efficiency and decrease size per industry demands. Perhaps TC108 can consider looking at this for the glorious coming of IEC62368-1, as there are power supplies being developed now that operate up to 30MHz. Brian -----Original Message----- From: CR [mailto:[email protected]] Sent: Wednesday, November 05, 2014 7:16 AM To: [email protected] Subject: Re: [PSES] New electrical phenomenon reproduced tonight! I suspect the effect seen with SMPS' is due to transients forcing operation outside the designed stability region of their controllers. If so, this would not be a new EM effect, but a common immunity problem. Cortland Richmond - ---------------------------------------------------------------- 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]>
