To make a quantum leap of several orders of magnitude, there is a purpose built ESD generator of some complexity in those spark initiated engines. For those with a distributor, there are two gaps - one at atmospheric pressure and one at a somewhat higher pressure. There maybe some technical information on spark performance related to pressure somewhere. This may give some insight to performance differences due to pressure changes - it just needs a little scaling down. =)
[email protected] wrote: Aside from secondary effects on the EUT (EUT not spec'd to operate at that pressure), I wouldn't expect air pressure to affect Contact discharge. But what about Air discharge testing? Paschen's Law says that breakdown voltage in a gas is affected by air pressure. See: <http://www.duniway.com/images/pdf/pg/Paschen-Curve.pdf> I don't think air pressure would enable or prevent the discharge, but how would the wavefront/risetime look? Pat Lawler EMC Engineer SL Power Electronics Corp. [email protected] wrote on 04/03/2008 08:06:08 AM: > This discussion is getting interesting. Given that the limits for > pressure in 61000-4-2 will only be approached in a few special > situations (high altitude labs, or labs in the very few places on > earth below sea level), this becomes the old “measure with a > micrometer, mark with chalk and cut with an axe†game. Yes, I can > measure the height of the column of mercury (a more common type of > manometer) with great precision, but the question to ask is “why?†> While atmospheric pressure can impact ESD (air discharge) results, > is it that critical? Somehow I doubt it. > > Ghery > From:Cortland Richmond [mailto:[email protected]] > Sent: Thursday, April 03, 2008 7:45 AM > To: Garnier, David S (GE Healthcare); Pettit, Ghery; EMC-PSTC > Subject: RE: Looking for Barometric pressure meter > > This is an *interesting* discussion. Yes, of course (I should have > know, too) the reading at the airport is normalized to sea level. > But one could without too much trouble apply it to the known > (surveyed) altitude and derive the actual pressure. > > I have however a metal picture of a Rube-Goldberg/Heath Robinson > plumbing setup making up a water barometer. Since the height of the > column of water is constant over any practical tubing diameter, one > might proudly display a calibration document applying only to the > Meter Stick used. > > Of course, one now needs to know the temperature. Is it sufficient > to calibrate a thermometer at only the the melting point of ice and > the boiling point of water? How about the latter alone -- since the > boiling point varies with pressure, if we _have_ a calibrated > thermometer, do we need a barometer? > > Cortland > KA5S > ----- Original Message ----- > From:Garnier, David S (GE Healthcare) > To: Pettit, Ghery;[email protected] > Sent:3/31/2008 8:27:16 AM > Subject:RE: Looking for Barometric pressure meter > > Hi Gary, > > Thank you for the important point... I too am one of those people > that would have said, "What?" ;-) > > > > In the past we have used the local Airport online readings for our > Baro readings. > > http://weather.noaa.gov/weather/current/KUES.html > > > > Recently, our quality people have been having fits about the lab > doing this. Questions such as: > > "When was it last calibrated?" " Was it an accredited Cal? "Do we > have access to the data?" > > > > Reguardless that GEHC & Airport are at the same elevation and that > our facilities are approximately > > 1 mile a apart does not cut slack with them. > > > > BTW, I am not exactly neutral in this controversity, I wrote the > original SPR (software complaint > > report) complaining concerning this practice. > > > > Anyhow, I appreciate your prespective as an "PP-ASEL" person, being > up front that is. > > > > Regards, > Dave Garnier > > > > PS: I have gotten 4 recommendations for the Vaisala PTB330 > instrument. Have you any experiance with this device? > > David Garnier > eGE HealthCare > ___________________________________________ > > David S. Garnier > Quality Assurance Technician > Quality-DI RA-EMC > 3000 N. Grandview Ave - M/S W-1250 > Waukesha, Wi. 53188 > Tel: 262.312.7246 > Cel: 414.899.7580 > > > > > > > > > > > > From:Pettit, Ghery [mailto:[email protected]] > Sent: Saturday, March 29, 2008 6:58 PM > To: [email protected]; Garnier, David S (GE Healthcare); [email protected] > Subject: RE: Looking for Barometric pressure meter > > The information provided by the FAA and weather guessers is pressure > corrected to sea level. It is not the actual pressure. I can get > an altimeter setting in Denver (mile high) or Olympia (206 ft MSL) > and it will be in the same range, even though the actual pressure in > Denver is about 5 inches of mercury lower. This is one of my > favorite questions when auditing a lab when they have a barometer on > the wall is that absolute pressure, or corrected to sea level? And > I usually get blank looks. And you want to report absolute pressure. > > > > Ghery Pettit > > PP-ASEL > > > > > > From:[email protected] [mailto:[email protected]] On Behalf Of > Cortland Richmond > Sent: Saturday, March 29, 2008 2:44 PM > To: Garnier, David S (GE Healthcare); [email protected] > Subject: RE: Looking for Barometric pressure meter > > > > Why not get the air pressure from the nearest FAA control tower by > radio? Critesfield Airport in Waukesha broadcasts airfield > information that includes updated barometric pressure > > http://www.critesfield.com/facilities/ > > > > > > > > Cortland > > KAS/6 > > > > > > ----- Original Message ----- > > From:Garnier, David S (GE Healthcare) > > To: [email protected] > > Sent:3/28/2008 10:25:25 AM > > Subject:Looking for Barometric pressure meter > > > > Hello, > > > > I am looking for advice or suggestions for the purchase of > a Barometric pressure meter for our EMC lab... > > - Bill You can say what you want about the South, but you never hear of anyone retiring and moving North!!! _____ You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access <http://us.rd.yahoo.com/evt=4752 /*http://tc.deals.yahoo.com/tc/blockbuster/text5.com> , No Cost. - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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