Greetings, Let me add something to Joe's position (which I agree with entirely) based upon my experience at a former job. Some products with no ground or not so great grounds will need time (one sec or sometimes more) between discharges to ensure that there is no build up of charge on the system. Not only does charge buildup reduce the effect of same polarity discharges, but just think of the discharge level when a unit with a few kV of charge suddenly gets hit with a -XkV event after the polarity change. The effective net discharge is way over the spec and can often cause perceived failures. For the case of no ground (say a handheld battery powered device), a high impedance drain should be used to remove the charge. Ever pick up a handheld device charged to around 8kV?
Best regards Dave Heald Joe Finlayson wrote: > > Amund, > > My experience has been that the labs would prefer to perform the ESD > tests at a rate of 1 pulse/second (pps) for the sake of efficiency. If the > product passes then it was completed in the least amount of time and > everyone's happy. If the product fails at 1 pps, then you are allowed to > decrease the pulse rate until the product passes. If it still fails at > lower rates (say 0.1 pps - one ESD event every 10 seconds), then you > probably have problems. I've had products fail at 1 pps and pass at 0.5 > pps. It took longer to run the test, but it passed and met the requirements > of the standard(s). My interpretation of the requirements is that there is > no maximum limit between ESD discharges. > > Thx, > > Joe > > -----Original Message----- > From: am...@westin.org [mailto:am...@westin.org] > Sent: Wednesday, August 01, 2001 4:07 PM > To: emc-p...@majordomo.ieee.org > Subject: ESD - time between successive discharges > > Dear members, > > >From IEC61000-4-2 and several EN-product standards, they specify the time > between successive discharges to be at least 1 second. > > But what is the maximum time between each pulse ? I can not see that it is > stated in any standards. I guess the test labs use 1 pulse pr second. > > I feel that the pulse rate can have influences on the EUT performance, so 1 > second compared to 3-5 seconds might be the difference between PASS and > FAIL. > > Any suggestions ? > > Best regards > Amund Westin > Oslo, Norway > > -- > Get your firstname@lastname email for FREE at http://Nameplanet.com/?su > > ------------------------------------------- > 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," > > ------------------------------------------- > 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," ------------------------------------------- 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,"
