Hi Dan, Contact discharge is meant to be applied to conductive surfaces. If a product has a plastic case, breakdown voltage (through seams and holes) is the important parameter. This is best done with air discharge, the object of which is not to have one.
Doug "Dan Kinney (A)" wrote: > > While we're on the topic, I have a question (actually a couple) regarding > air discharge. Since contact discharge is the preferred method, as stated > in an earlier message and in EN61000-4-2, Paragraph 5, why would one perform > the Air Discharge method? The same paragraph states "Air discharges shall > be used where contact discharge cannot be applied." What conditions would > make it such that contact discharge could not be applied? > > Thanks in advance. > Dan Kinney > Horner APG > > > -----Original Message----- > > From: Douglas C. Smith [SMTP:d...@emcesd.com] > > Sent: Friday, April 20, 2001 2:54 PM > > To: Terry Meck > > Cc: emc-p...@ieee.org > > Subject: Re: ESD generators max Contact discharge level > > > > > > Hi Terry and the group, > > > > Besides the question of finding a generator that can reach the level you > > mention, I am not aware of any natural ESD event that approaches the > > interference potential of even an 8 kV contact discharge. The problem > > comes in that high voltage air discharges have relatively slow > > risetimes, for 16 kV on the order of tens of ns, whereas contact > > discharges maintain a better than 1 ns risetime at all voltages. This > > makes for a much smaller dt to go along with the greater di to make a > > di/dt that is much higher, more than an order of magnitude, than you > > will see for these voltages in nature. > > > > Maybe if you were making atom bomb trigger mechanisms there would be a > > justification for this kind of testing, but not for real equipment. > > > > On the other hand very low voltage (and energy) events, such as jinjling > > change have very high di/dt because of the tens of ps risetimes that > > occur at low voltage. The combination of high voltage (and energy) with > > fast risetimes is too severe and meeting such a test is a waste of money > > for most equipment. > > > > Doug > > > > Terry Meck wrote: > > > > > > Hello again: > > > > > > Does anyone recall if there were any standard called for or ESD > > generator that simulated as the case may be => +-10 kV CONTACT discharge. > > > > > > We have a customer that is specifying passing +-16 kV ESD without > > referring to AIR or Contact discharge. I am inclined to ask what they > > have in mind since I have not seen any generators that go that high in the > > Contact mode. > > > I suspect the writer of the SOW knows nothing and the engineering group > > only thinks Air Discharge. > > > > > > What do you all think? > > > > > > Terry J. Meck > > > Accu-Sort Systems Inc. > > > > > > ------------------------------------------- > > > 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: > > > majord...@ieee.org > > > with the single line: > > > unsubscribe emc-pstc > > > > > > For help, send mail to the list administrators: > > > Michael Garretson: pstc_ad...@garretson.org > > > Dave Heald davehe...@mediaone.net > > > > > > For policy questions, send mail to: > > > Richard Nute: ri...@ieee.org > > > Jim Bacher: j.bac...@ieee.org > > > > > > All emc-pstc postings are archived and searchable on the web at: > > > http://www.rcic.com/ click on "Virtual Conference Hall," > > > > -- > > ------------------------------------------------------- > > ___ _ Doug Smith > > \ / ) P.O. Box 1457 > > ========= Los Gatos, CA 95031-1457 > > _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 > > / /\ \ ] / /\ \ Mobile: 408-858-4528 > > | q-----( ) | o | Email: d...@dsmith.org > > \ _ / ] \ _ / Website: http://www.dsmith.org > > ------------------------------------------------------- > > > > ------------------------------------------- > > 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: > > majord...@ieee.org > > with the single line: > > unsubscribe emc-pstc > > > > For help, send mail to the list administrators: > > Michael Garretson: pstc_ad...@garretson.org > > Dave Heald davehe...@mediaone.net > > > > For policy questions, send mail to: > > Richard Nute: ri...@ieee.org > > Jim Bacher: j.bac...@ieee.org > > > > All emc-pstc postings are archived and searchable on the web at: > > http://www.rcic.com/ click on "Virtual Conference Hall," -- ------------------------------------------------------- ___ _ Doug Smith \ / ) P.O. Box 1457 ========= Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-----( ) | o | Email: d...@dsmith.org \ _ / ] \ _ / Website: http://www.dsmith.org ------------------------------------------------------- ------------------------------------------- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
