I really hope that you are not using one of my power supplies. If you have to use a filter module in front of the power supply, then you might want to consider another vendor.
What is the reference point for the 3500V measurement? Line to ground surges have some strange properties in some end-use installations, as they can create standing waves along the chassis that can ring back into the DC output of the power supply - which will probably blow the output diode. So if it is a standing wave - move the node point. Recently, I re-produced a surge failure on the customer's end-use construction at 3kV, where the power supply, by itself, had been tested up to 8kV with no problems. Yet another reason why I think EMC reports for component power supplies are not necessarily representative of end-use performance. As a fellow 'Brian', you deserve the best. Brian -----Original Message----- From: [email protected] [mailto:[email protected]]On Behalf Of Kunde, Brian Sent: Thursday, September 09, 2010 8:47 AM To: [email protected] Subject: RE: Surge Pulse After Line Filter Bill, Where are you monitoring the surge voltage? At the output of the surge generator? In our case, the generator output looks fine, but when we look at the surge pulse at the input to our power supply (after our line filter) the surge pulse is much larger. Case in point, I am currently working on piece of equipment that has a 500 watt 24Vdc power supply connected after a 60 amp line filter. The 2KV Line to PE surge pulse is 3500 voltage at the power supply. The Other Brian From: [email protected] [mailto:[email protected]] On Behalf Of Bill Owsley Sent: Thursday, September 09, 2010 11:25 AM To: [email protected]; Brian O'Connell Subject: RE: Surge Pulse After Line Filter What is the setup, the equipment arrangement, etc. for the surge test? I monitor the surge voltage and have not seen the common occurrence of much higher voltages, so I'm wondering what am I missing. I'm not Brian, either one of them... Bill --- On Tue, 9/7/10, Brian O'Connell <[email protected]> wrote: From: Brian O'Connell <[email protected]> Subject: RE: Surge Pulse After Line Filter To: [email protected] List-Post: [email protected] Date: Tuesday, September 7, 2010, 5:09 PM Only one of my esteemed power supply competitors has replied - most dissapointing. Another important principle for 'surge' ratings for component power supplies is the energy. The I^2T is what sends the power supply to the dark side. A customer from the Great State of Australia was killing my children. Cannot be, said I, as all knew the unit was rated level 3 and tested higher. But I must see, said I, as I was still in disbelief. Set this before your beady green eyes, the customer said, and I did. Behold, the addition of evil caps in front of the sacred input filter. Sacrilege said I. I bade them a non-fond farewell. The intended end-use of X and Y caps is NOT surge suppression. They are rated for some big hits, but they are NOT intended to function as a VDR within the meaning of IEC60950-1 annex Q. These caps are considered part of the 'line' filter. But it should be noted that for some resultant surge waveforms, an input-filter cap will appear as a very low Z for a short period before the VDR starts to conduct. There can be an interaction between a front-end pi filter and the resultant shape of the waveform that is propagated into the power supply during a surge event. This is why I re-test surge immunity if the designer changes LC values. Pat, from SL Power, noted the common combo of VDRs and gas tubes. The only problem with gas tubes is turn-on time. But once the gas ionizes, the conduction is on hard, regardless of the waveform and adjacent L. But the more important issue - who among us shall be considered the original 'Brian' ? Brian -----Original Message----- From: [email protected] [mailto:[email protected]]On Behalf Of Fred Townsend Sent: Wednesday, September 01, 2010 1:25 PM To: Kunde, Brian Cc: [email protected] Subject: Re: Surge Pulse After Line Filter Dear Other: It seems like this discussion has been around for a long time in a slightly different form. Input capacitors (x-y caps?) help kill the surges. As I recall the size of these caps is limited by the allowable leakage currents. Maybe someone can comment on the solution to that problem. Fred Townsend DC to Light Kunde, Brian wrote: Most all over the counter power supplies will pass the 2KV Line - PE surge immunity test (IEC 61000-4-5) when tested stand-a-lone, however, when these power supplies are used in an assembly with other Mains driven devices through a large Line Filter, the surge pulse seen at the power supply can be much larger in amplitude. During the 2KV Line-PE test it is not unusual to see a peak that exceeds 3KV or more. This is a common phenomenon. Most power supply can handle the higher surge pulse, but some have trouble with it ranging from restarting to blowing its guts out. The problem seems to be getting worst. We are having a hard time finding power supplies to pass under these conditions. Is there a simple solution to this problem? Are line - PE surge suppressors the only solution? Are they allowed in products going to Europe? I have heard that northern Europe doesn't allow line to PE surge suppression due to safety. Has this changed? Is there a good over the counter device I can buy and drop in my product? If a surge suppressor is used, what requirements does it have to meet? I hear gas tubes are a must. How about overcurrent protection? Where would the fuse go? In the PE line? I have seen surge suppressors with UL and CSA agency approval, but not with a European agency approval (I may just be looking in the wrong place). Is this evidence they are not allowed in Europe? Thank you, The Other Brian - ---------------------------------------------------------------- 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.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html 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]>
