About five years ago STMicro [I think] designed a custom protection device for HP [I think] that was the corollary of a zener, in that it allowed current through up to a value, then kept stopping any increase in current even with voltages over 3KV. I believe it was bipolar processing so could take impulse heat without demise.
For those short spikes it's time to start offering that component to the EMC community. Thinking about it 2 ohms, 500 V that's some husky current possibility, at least without something else like a distributed resistance, or a 1 mH choke, but a choke can be large if it needs to pass DC current even as low as 1 Amp. Guess one could make an 'active' inductor to do the same, just to handle the spike. But then again, you'd have to use 1KV breakdown parts to get good margin. Robert > Amund, > > For 12V DC and 1kV (40 ohm) surge I prefer transils (STM:SM6T18A) because > of lower voltage during surge. > I have no experience with 2 ohm surges. > > Piotr Galka > > ----- Original Message ----- > From: Amund Westin > To: [email protected] > Sent: Monday, October 12, 2009 9:34 PM > Subject: Surge protection components - DC line > > > 24VDC port shall be protected against 1kV (line-earth 10ohm) and 500V > (line-line 2ohm). (ref.IEC61000-4-5 8/20us pulse) > > > > Should I go for MOVs or tranzorbs? > > > > I have good experience with MOVs on 230VAC ports, but have not done any > work on DC ports. > > > > #Amund > > > > - > ---------------------------------------------------------------- > 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]> > - 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]>
