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:[email protected]] > Sent: Friday, April 20, 2001 2:54 PM > To: Terry Meck > Cc: [email protected] > 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: > > [email protected] > > with the single line: > > unsubscribe emc-pstc > > > > For help, send mail to the list administrators: > > Michael Garretson: [email protected] > > Dave Heald [email protected] > > > > For policy questions, send mail to: > > Richard Nute: [email protected] > > Jim Bacher: [email protected] > > > > 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: [email protected] > \ _ / ] \ _ / 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: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson: [email protected] > Dave Heald [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > http://www.rcic.com/ click on "Virtual Conference Hall," ------------------------------------------- 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
