RE: [PSES] Discharge capacitors
-Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of ce- test, qualified testing bv - Gert Gremmen Sent: Friday, November 06, 2009 3:02 AM To: m...@sfo.com; emc-pstc@LISTSERV.IEEE.ORG Subject: RE: [PSES] Discharge capacitors Massive conductors are too often abused for emc grounding, and I needed a simple rule of thumb to show the difference. Regards, Ing. Gert Gremmen I shall now stick out my own neck and declare that massive is always better, if not technically, then certainly politically! A clever EMC engineer can make an elegant little filter for a rocket guidance package, but the truly gifted EMC guy can justify his filter as comprising the kinetic kill package! Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military Avionics EMC Is Our Specialty - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Discharge capacitors
Thank you, filed away, and presently foundering on copies from Radov Here are the references I used. Rakov Uman are leaders in the field of lightning and most lightning conferences will have Rakov on the committee. Lightning: Physics and Effects ~ Vladimir A. Rakov Martin A. Uman (Paperback) http://www.amazon.com/Lightning-Physics-Effects-Vladimir-Rakov/dp/0521035414 Price: 117 $ (my hard cover version cost 250 $) Description This is the first book to cover essentially all aspects of lightning, including lightning physics, lightning protection, and the interaction of lightning with a variety of objects and systems as well as with the environment. Accessible to the technical non-expert, it is addressed to anyone interested in lightning and its effects. # Paperback: 700 pages # Publisher: Cambridge University Press, 2007 # ISBN-10: 0521035414 # ISBN-13: 978-0521035415 # Product Dimensions: 10.9 x 8.2 x 1.5 inches # Shipping Weight: 3.4 pounds (you need weight training to open the book) Website: http://plaza.ufl.edu/rakov/ (lots of downloads of papers from 2008 to 1991) If I was asked if I had met a genius then Dr. Ron Standler would be my reply. He was so far ahead of his time that his 1989 book still has lots of value today. Recently I used the Standler cubic approximation for the 8/20 waveform for an ITU-T contribution. Protection of Electronic Circuits from Overvoltages - Ronald B. Standler http://store.doverpublications.com/0486425525.html Price$26.95 Availability: In Stock Format: Book ISBN: 0486425525 Page Count: 464 Dimensions: 6 1/4 x 9 1/4 This text presents practical rules and strategies for circuits designed to protect electronic systems from damage by transient overvoltages. The treatment covers symptoms and threats, fundamental remedies, types of protective devices, applications of protective devices, validation of protective measures,and much more. 1989 edition. Website: http://www.rbs2.com/blitz.htm (Unfortunately he has removed his papers on lightning and equipment protection from this site) Regards Mick Maytum UK - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Discharge capacitors
Robert Macy wrote: Excellent reply! Do you have a URL to get copies? Here are the references I used. Rakov Uman are leaders in the field of lightning and most lightning conferences will have Rakov on the committee. Lightning: Physics and Effects ~ Vladimir A. Rakov Martin A. Uman (Paperback) http://www.amazon.com/Lightning-Physics-Effects-Vladimir-Rakov/dp/0521035414 Price: 117 $ (my hard cover version cost 250 $) Description This is the first book to cover essentially all aspects of lightning, including lightning physics, lightning protection, and the interaction of lightning with a variety of objects and systems as well as with the environment. Accessible to the technical non-expert, it is addressed to anyone interested in lightning and its effects. # Paperback: 700 pages # Publisher: Cambridge University Press, 2007 # ISBN-10: 0521035414 # ISBN-13: 978-0521035415 # Product Dimensions: 10.9 x 8.2 x 1.5 inches # Shipping Weight: 3.4 pounds (you need weight training to open the book) Website: http://plaza.ufl.edu/rakov/ (lots of downloads of papers from 2008 to 1991) If I was asked if I had met a genius then Dr. Ron Standler would be my reply. He was so far ahead of his time that his 1989 book still has lots of value today. Recently I used the Standler cubic approximation for the 8/20 waveform for an ITU-T contribution. Protection of Electronic Circuits from Overvoltages - Ronald B. Standler http://store.doverpublications.com/0486425525.html Price$26.95 Availability: In Stock Format: Book ISBN: 0486425525 Page Count: 464 Dimensions: 6 1/4 x 9 1/4 This text presents practical rules and strategies for circuits designed to protect electronic systems from damage by transient overvoltages. The treatment covers symptoms and threats, fundamental remedies, types of protective devices, applications of protective devices, validation of protective measures,and much more. 1989 edition. Website: http://www.rbs2.com/blitz.htm (Unfortunately he has removed his papers on lightning and equipment protection from this site) Regards Mick Maytum UK - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org David Heald dhe...@gmail.com
Re: [PSES] Discharge capacitors
In message 1157.66.81.42.36.1257524245.squir...@cp01.sfo.com, dated Fri, 6 Nov 2009, m...@sfo.com writes: It's almost like once it is brought into existance, it doesn't go away, one just moves it about. There is a law - Conservation of Energy. But it all ends up as heat, somewhere; it can never disappear (not even into a black hole). -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK Help stamp out intolerance! - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Discharge capacitors
Excellent reply! Do you have a URL to get copies? I said 'significant', not 'spectral bandwidth of energy' I assumed these frequencies were of interest, because coupling is increased, breakdown is more likely to occur, and I thought the goal was to make a connection system with broadband characteristics. And, as we both know, inductance can certainly ruin the high frequency end of a system. Your point is well taken about how to refer to lightning energy. It's almost like once it is brought into existance, it doesn't go away, one just moves it about. And, the best we can hope for is to keep it out of our systems while all that's happening. Robert Robert Macy wrote: Assuming most of lightning energy is significant between 1MHz to 100MHz, calculate each conductor's characteristics at 10MHz and at 100MHz using 2D finite element analysis. This is at variance with real lightning and the simulated lightning generators for equipment test. Lightning Physics and Effects (Rakov Uman) states that electromagnetic signal levels from lightning peak in the 5 to 10 kHz region, then fall inversely with frequency up to 10 MHz and then fall inversely with the square root of frequency to 10 GHz. Actual simulated lightning generators, such as the 1.2/50 and 10/1000 obviously have an even more restricted spectrum. Strandler (Protection of Electronic circuits from overvoltages) shows the spectrum of several lightning test pulses. The --6 decibel spectrum fall-off points are variously 300 Hz 10/1000, 5 kHz 1.2/50, 30 kHz 8/20 and 200 kHz for the 100 kHz ring wave. Non-lightning waveshapes like EFT and HEMP have a much broader frequency spectrum. Also please be careful when talking about lightning energy - this can lead to dreadful statements like The lightning protection system diverts the lightning energy to earth. It doesn't, current gets diverted to ground and the amount of energy in the earth depends on the earth potential rise - something the lightning doesn't have control over. Mick UK - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] Discharge capacitors
Point well taken. I should have elaborated a bit more on why I concentrated at the higher frequencies. Robert Lightning detectors function (among other frequencies) down to 10 kHz. My opinion is that most of the lightning energy is below 1 MHz. Regards, Ing. Gert Gremmen g.grem...@cetest.nl mailto:g.grem...@cetest.nl www.cetest.nl Kiotoweg 363 3047 BG Rotterdam T 31(0)104152426 F 31(0)104154953 Before printing, think about the environment. Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens Fred Townsend Verzonden: Friday, November 06, 2009 11:52 AM Aan: m...@sfo.com CC: emc-pstc@LISTSERV.IEEE.ORG Onderwerp: Re: [PSES] Discharge capacitors Robert it is difficult to validate your models without knowing more about them but they are suspect when they fail to uphold empirically derived practice that has existed for longer than field solvers. You certainly stick your neck out when you say: CONCLUSION: Round is always better. I can think of numerous exceptions, exceptions that may prove the rule. In fairness many of the exceptions are caused effects not considered by your models but are real world, nevertheless. ( I thought this discussion was about best practice.) For instance if one is terminating in a, PCB or just a tab, round tube requires a round to rectangular conversion. How may that conversion effect corona? As you said nature doesn't like 'pointy' stuff. It would be folly to characterize the problem as purely one of inductance. We like to model lightning as pulse but we know lightning is often a damped sinusoid. Where does the sinusoid come from? We know that if hit a LC circuit with an impulse function, the circuit will ring at its natural frequency. Could this be the source of the sinusoid? If we suspect there are resonance effects, then clearly we must address capacitance and L/C ratios and transmission line effects as well. Clearly your 2D field solver isn't going to do that. Finally in your models, isn't there going to be significant energy below 10 MHz? My AM broadcast radio certainly thinks there is whenever lightning strikes nearby. Why do you show reactance for ribbon and resistance for tube? Is that an error of missing 'j's or is this truly apples and oranges? Best regards, Fred Townsend DC to Light m...@sfo.com wrote: Flat rectangular is NOT better than a round tube if each have the same circumference. The round tube has lower inductance than a flat ribbon conductor of comparable circumference. Makes sense, because Nature abhors 'pointy' stuff. This statement is based upon a comparison analyzing the two structures using finite element analysis, femm 4.2. Given: solid ribbon copper conductor, 1 inch wide and 120 mils thick copper tube, 0.75 inch outside diameter and 120 mils wall thickness The two circumferences are approximately the same. Rectangle 2 * (0.12+1) = 2.24 inches Tube pi * 0.7 = 2.20 inches Which is a better conductor? Assume infinitely long, straight conductors. Assuming most of lightning energy is significant between 1MHz to 100MHz, calculate each conductor's characteristics at 10MHz and at 100MHz using 2D finite element analysis. Method: place each conductor in a 24 inch diameter metal 'tube' to provide return current and represent infinity. Note: I also used single conductors in free space with current return at infinity. Values changed, but the conclusions did not change. Use a 12 inch length to reference values per ft. Mesh was set to be fine near the surfaces of the conductors, so that even with hgih frequency currents inside the conductors were accurately represented. Skin depth was more than 3 nodes. From results, the current as a function of depth into the conductors matched expected values. Plots of current/eddy currents verified mesh was of suficient density for these calculations. TABLE RESULTS: Ribbon - Solid mesh 69,406 10MHz 210 nH/ft 0.00347 W 13.2j ohm/ft 83 milliohm/ft 100MHz 210 nH/ft 0.0115W 132j ohm/ft0.15 ohm/ft Tube - Hollow mesh 90,233 100MHz 203 nH/ft 0.00239W 12.8 ohm/ft69 mOhm/ft 100MHz 203 nH/ft 0.00732 128 ohm/ft 0.12 ohm/ft It was interesting to note that with a wall thickness of more than 10 mils, at these frequencies the metal was doing nothing but physically supporting the outside layer. CONCLUSION: Round is always better. Robert As a rule of thumb, a conductor has an (self)inductance proportionally inverse with it's circumference (if fact the shortest way the magnetic field lines will take). Big flat conductors always perform better then round ones, as they have the highest circumference per kilo. Litz and silver(gold) coated conductors do contribute to the real part of the impedance (=resistance) properties only. Litz
Re: [PSES] Discharge capacitors
Thank you for replying. For corona, round IS better. Rounding the edges of a ribbon cable are better than square shape. As empirical evidence, Molecularly 'rounding' is better. -- while at HP, silver plating *and* polishing the plating resulted in higher Q for the cavity resonators. You correctly point out that I concentrated on a single value, inductance. Not the whole picture. But, at least with one foot of conductor at 100MHz with 1/4 wavelength in air of 30 inches, we are starting to get close to transmission line effects. But, also, as you point out, most energy is in lower than 10MHz. Most of the energy I've seen in ESD ievents [miniature lightning] is in the 1-3MHz ranges. After changing the structures for 'better' grounding the lower frequencies were reduced, moving the peak out to 20-30MHz. From my experience in trying to model a structure to control the design, ringing relates to the tank circuit you have left. Oops! left the j's off those terms, but at least they are below inductance. What caught my eye doing this, is the large disparity between resistive losses and extremely high reactive impedance. Didn't realize that it was going to be so big. So that just verifies my next rule: A connection is only a connection if it is wider than long, else it's definitely an inductor. Robert Robert it is difficult to validate your models without knowing more about them but they are suspect when they fail to uphold empirically derived practice that has existed for longer than field solvers. You certainly stick your neck out when you say: CONCLUSION: Round is always better. I can think of numerous exceptions, exceptions that may prove the rule. In fairness many of the exceptions are caused effects not considered by your models but are real world, nevertheless. ( I thought this discussion was about best practice.) For instance if one is terminating in a, PCB or just a tab, round tube requires a round to rectangular conversion. How may that conversion effect corona? As you said nature doesn't like 'pointy' stuff. It would be folly to characterize the problem as purely one of inductance. We like to model lightning as pulse but we know lightning is often a damped sinusoid. Where does the sinusoid come from? We know that if hit a LC circuit with an impulse function, the circuit will ring at its natural frequency. Could this be the source of the sinusoid? If we suspect there are resonance effects, then clearly we must address capacitance and L/C ratios and transmission line effects as well. Clearly your 2D field solver isn't going to do that. Finally in your models, isn't there going to be significant energy below 10 MHz? My AM broadcast radio certainly thinks there is whenever lightning strikes nearby. Why do you show reactance for ribbon and resistance for tube? Is that an error of missing 'j's or is this truly apples and oranges? Best regards, Fred Townsend DC to Light m...@sfo.com wrote: Flat rectangular is NOT better than a round tube if each have the same circumference. The round tube has lower inductance than a flat ribbon conductor of comparable circumference. Makes sense, because Nature abhors 'pointy' stuff. This statement is based upon a comparison analyzing the two structures using finite element analysis, femm 4.2. Given: solid ribbon copper conductor, 1 inch wide and 120 mils thick copper tube, 0.75 inch outside diameter and 120 mils wall thickness The two circumferences are approximately the same. Rectangle 2 * (0.12+1) = 2.24 inches Tube pi * 0.7 = 2.20 inches Which is a better conductor? Assume infinitely long, straight conductors. Assuming most of lightning energy is significant between 1MHz to 100MHz, calculate each conductor's characteristics at 10MHz and at 100MHz using 2D finite element analysis. Method: place each conductor in a 24 inch diameter metal 'tube' to provide return current and represent infinity. Note: I also used single conductors in free space with current return at infinity. Values changed, but the conclusions did not change. Use a 12 inch length to reference values per ft. Mesh was set to be fine near the surfaces of the conductors, so that even with hgih frequency currents inside the conductors were accurately represented. Skin depth was more than 3 nodes. From results, the current as a function of depth into the conductors matched expected values. Plots of current/eddy currents verified mesh was of suficient density for these calculations. TABLE RESULTS: Ribbon - Solidmesh 69,406 10MHz 210 nH/ft 0.00347 W 13.2j ohm/ft83 milliohm/ft 100MHz210 nH/ft 0.0115W 132j ohm/ft 0.15 ohm/ft Tube - Hollow mesh 90,233 100MHz203 nH/ft 0.00239W 12.8 ohm/ft 69 mOhm/ft 100MHz203 nH/ft 0.00732 128 ohm/ft 0.12 ohm/ft It was interesting to note that with a wall thickness of more than 10 mils, at these
Re: [PSES] Discharge capacitors
In message 4af43076.4020...@gmail.com, dated Fri, 6 Nov 2009, Mick Maytum on Gmail mjmay...@gmail.com writes: Thus think current and the voltage the object develops ? not energy. It looks pretty energetic to me. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK Help stamp out intolerance! - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Discharge capacitors
Actually OD of 0.70 is closer to matching the circumference. Plus, I anticipated that by rounding downwards, would tend to make the round tube have slightly higher inductance. For density calculations, the ratio of ribbon cross section area to tube cross section area is approx 0.55 Yes, you correctly noted, I should have made the tube's wall thickness 60 mils, NOT 120 mils. But, I was not addressing effect/weight, but rather the comparison effect/shape. Robert In message 1937.66.81.215.25.1257470854.squir...@cp01.sfo.com, dated Thu, 5 Nov 2009, m...@sfo.com writes: solid ribbon copper conductor, 1 inch wide and 120 mils thick copper tube, 0.75 inch outside diameter and 120 mils wall thickness The two circumferences are approximately the same. Rectangle 2 * (0.12+1) = 2.24 inches Tube pi * 0.7 = 2.20 inches Why 0.7? The OD is 0.75, giving a circumference of 2.36 inches. Also, the criterion used to claim that flat is better is 'circumference per kilo(gram)'. What are the lineal densities of your example conductors? -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK Help stamp out intolerance! - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Discharge capacitors
Thank you for your reply. You make a good point: the importance of matching 'design to function'. These analyses were purposely done on 'isolated' conductors, because the original intent was to make a conductor between two points - a lightning simulator. You make a great point in talking about the 'extra' fields involved when the conductor is used to make a coil and reappears near itself. However, I have NEVER gotten full conductivity in a flat foil. If the thin dimension is equal to the skin depth, for the wide dimension all the carriers bunch up to the edges equal to the thickness of the foil, and (again) most of the middle section is wasted. For a coil made from a round conductor, the carriers all bunch along the conductors at the minimum radius to the center of the coil, which means the outer sides of the conductors are wasted. Just have to match shape to function. Robert The setup is rather artificial in that it compares isolated conductors. The situation flips around for proximal conductors due to proximity effect. Try modeling a coil with a foil winding versus round wire. Flat adjacent surfaces perform better than adjacent round ones because the current bunching is less pronounced in the foil. Also note the huge difference in area efficiency. As you mentioned, for small skin depth compared to diameter most circular cross sectional area is electrically wasted. Foil of suitable thickness (not too thin and not too thick for the frequency of interest) will carry current throughout the entire cross section, although there will be higher current density at the foil edges than down the center. Round is not a panacea, and in certain situations can be distinctly inferior. Orin Laney On Thu, 5 Nov 2009 17:27:34 -0800 Robert Macy m...@sfo.com writes: Flat rectangular is NOT better than a round tube if each have the same circumference. The round tube has lower inductance than a flat ribbon conductor of comparable circumference. Makes sense, because Nature abhors 'pointy' stuff. This statement is based upon a comparison analyzing the two structures using finite element analysis, femm 4.2. Given: solid ribbon copper conductor, 1 inch wide and 120 mils thick copper tube, 0.75 inch outside diameter and 120 mils wall thickness The two circumferences are approximately the same. Rectangle 2 * (0.12+1) = 2.24 inches Tube pi * 0.7 = 2.20 inches Which is a better conductor? Assume infinitely long, straight conductors. Assuming most of lightning energy is significant between 1MHz to 100MHz, calculate each conductor's characteristics at 10MHz and at 100MHz using 2D finite element analysis. Method: place each conductor in a 24 inch diameter metal 'tube' to provide return current and represent infinity. Note: I also used single conductors in free space with current return at infinity. Values changed, but the conclusions did not change. Use a 12 inch length to reference values per ft. Mesh was set to be fine near the surfaces of the conductors, so that even with hgih frequency currents inside the conductors were accurately represented. Skin depth was more than 3 nodes. From results, the current as a function of depth into the conductors matched expected values. Plots of current/eddy currents verified mesh was of suficient density for these calculations. TABLE RESULTS: Ribbon - Solid mesh 69,406 10MHz210 nH/ft0.00347 W 13.2j ohm/ft 83 milliohm/ft 100MHz210 nH/ft0.0115W 132j ohm/ft0.15 ohm/ft Tube - Hollowmesh 90,233 100MHz203 nH/ft0.00239W 12.8 ohm/ft69 mOhm/ft 100MHz203 nH/ft0.00732 128 ohm/ft0.12 ohm/ft It was interesting to note that with a wall thickness of more than 10 mils, at these frequencies the metal was doing nothing but physically supporting the outside layer. CONCLUSION: Round is always better. Robert As a rule of thumb, a conductor has an (self)inductance proportionally inverse with it's circumference (if fact the shortest way the magnetic field lines will take). Big flat conductors always perform better then round ones, as they have the highest circumference per kilo. Litz and silver(gold) coated conductors do contribute to the real part of the impedance (=resistance) properties only. Litz by increasing the conductive surfaces so reducing the resistance increase caused by the skin effect. Regards, Ing. Gert Gremmen g.grem...@cetest.nl mailto:g.grem...@cetest.nl www.cetest.nl Kiotoweg 363 3047 BG Rotterdam T 31(0)104152426 F 31(0)104154953 - 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 emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at:
Re: [PSES] Discharge capacitors
John Woodgate wrote: In message 4af40b5b.2020...@gmail.com mailto:4af40b5b.2020...@gmail.com , dated Fri, 6 Nov 2009, Mick Maytum on Gmail mjmay...@gmail.com mailto:mjmay...@gmail.com writes: Also please be careful when talking about lightning energy - this can lead to dreadful statements like The lightning protection system diverts the lightning energy to earth. It doesn't, current gets diverted to ground and the amount of energy in the earth depends on the earth potential rise - something the lightning doesn't have control over. Where does the energy go, if not into the mass of the planet? Nothing to do with energy being moved but charge moving. The initial potential difference between the cloud charge region and ground is estimated to be between 50 MV and 500 MV (Rakov Uman). Any voltage developed by a lightning struck object is going to be insignificant compared the cloud ground voltage. Thus the cloud to ground discharge can be thought of as a current source. A lot of the discharge energy isn't developed in the struck object (Rakov Uman reckon values of some 50 GJ occur) There is a long-duration low-level lightning current that is effectively a rectangular current pulse - this makes the maths simple. The typical parameters for this (IEC 61312-1) are Q = 150 C, Td = 0.5 s and I = 300 A. Assume the LPS managed to divert all this current to earth. If the earthing resistance was 1 ohm a voltage of 300 V would be developed, making a power of 90 kW for 0.5 s and a ground energy of 45 kJ. Now a 1 ohm ground resistance is exception. If I had used 10 ohms everything would have been 10 times bigger - then I would have to have brought in HV soil ionisation effects which lowers the effective earth resistance. Thus think current and the voltage the object develops — not energy. (The closest the lightning people get to energy is something called the current action integral, which you and I know as i-squared-t. This factor is useful for wire fusing) Once the lightning current enters a network of multiple paths then the surge source impedance becomes that of the network, but that's another story! Mick Maytum UK - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org David Heald dhe...@gmail.com
Re: [PSES] Discharge capacitors
In message 4af40b5b.2020...@gmail.com, dated Fri, 6 Nov 2009, Mick Maytum on Gmail mjmay...@gmail.com writes: Also please be careful when talking about lightning energy - this can lead to dreadful statements like The lightning protection system diverts the lightning energy to earth. It doesn't, current gets diverted to ground and the amount of energy in the earth depends on the earth potential rise - something the lightning doesn't have control over. Where does the energy go, if not into the mass of the planet? -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK Help stamp out intolerance! - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Discharge capacitors
Robert Macy wrote: Assuming most of lightning energy is significant between 1MHz to 100MHz, calculate each conductor's characteristics at 10MHz and at 100MHz using 2D finite element analysis. This is at variance with real lightning and the simulated lightning generators for equipment test. Lightning Physics and Effects (Rakov Uman) states that electromagnetic signal levels from lightning peak in the 5 to 10 kHz region, then fall inversely with frequency up to 10 MHz and then fall inversely with the square root of frequency to 10 GHz. Actual simulated lightning generators, such as the 1.2/50 and 10/1000 obviously have an even more restricted spectrum. Strandler (Protection of Electronic circuits from overvoltages) shows the spectrum of several lightning test pulses. The –6 decibel spectrum fall-off points are variously 300 Hz 10/1000, 5 kHz 1.2/50, 30 kHz 8/20 and 200 kHz for the 100 kHz ring wave. Non-lightning waveshapes like EFT and HEMP have a much broader frequency spectrum. Also please be careful when talking about lightning energy - this can lead to dreadful statements like The lightning protection system diverts the lightning energy to earth. It doesn't, current gets diverted to ground and the amount of energy in the earth depends on the earth potential rise - something the lightning doesn't have control over. Mick UK - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org David Heald dhe...@gmail.com
RE: [PSES] Discharge capacitors
Well your calculation shows that they are approximately equal, with a slight advantage to the tube. Both intuitively and calculations seem correct. When I wrote the comparison I was thinking of massive conductors not tubes, as tube conductors normally find no place in electronics. Especially when they are 0.75 in diameter. Massive conductors are too often abused for emc grounding, and I needed a simple rule of thumb to show the difference. Regards, Ing. Gert Gremmen g.grem...@cetest.nl www.cetest.nl Kiotoweg 363 3047 BG Rotterdam T 31(0)104152426 F 31(0)104154953 Before printing, think about the environment. Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens m...@sfo.com Verzonden: Friday, November 06, 2009 2:28 AM Aan: emc-pstc@LISTSERV.IEEE.ORG Onderwerp: RE: [PSES] Discharge capacitors Flat rectangular is NOT better than a round tube if each have the same circumference. The round tube has lower inductance than a flat ribbon conductor of comparable circumference. Makes sense, because Nature abhors 'pointy' stuff. This statement is based upon a comparison analyzing the two structures using finite element analysis, femm 4.2. Given: solid ribbon copper conductor, 1 inch wide and 120 mils thick copper tube, 0.75 inch outside diameter and 120 mils wall thickness The two circumferences are approximately the same. Rectangle 2 * (0.12+1) = 2.24 inches Tube pi * 0.7 = 2.20 inches Which is a better conductor? Assume infinitely long, straight conductors. Assuming most of lightning energy is significant between 1MHz to 100MHz, calculate each conductor's characteristics at 10MHz and at 100MHz using 2D finite element analysis. Method: place each conductor in a 24 inch diameter metal 'tube' to provide return current and represent infinity. Note: I also used single conductors in free space with current return at infinity. Values changed, but the conclusions did not change. Use a 12 inch length to reference values per ft. Mesh was set to be fine near the surfaces of the conductors, so that even with hgih frequency currents inside the conductors were accurately represented. Skin depth was more than 3 nodes. From results, the current as a function of depth into the conductors matched expected values. Plots of current/eddy currents verified mesh was of suficient density for these calculations. TABLE RESULTS: Ribbon - Solid mesh 69,406 10MHz 210 nH/ft 0.00347 W 13.2j ohm/ft83 milliohm/ft 100MHz 210 nH/ft 0.0115W 132j ohm/ft 0.15 ohm/ft Tube - Hollow mesh 90,233 100MHz 203 nH/ft 0.00239W 12.8 ohm/ft 69 mOhm/ft 100MHz 203 nH/ft 0.00732 128 ohm/ft 0.12 ohm/ft It was interesting to note that with a wall thickness of more than 10 mils, at these frequencies the metal was doing nothing but physically supporting the outside layer. CONCLUSION: Round is always better. Robert As a rule of thumb, a conductor has an (self)inductance proportionally inverse with it's circumference (if fact the shortest way the magnetic field lines will take). Big flat conductors always perform better then round ones, as they have the highest circumference per kilo. Litz and silver(gold) coated conductors do contribute to the real part of the impedance (=resistance) properties only. Litz by increasing the conductive surfaces so reducing the resistance increase caused by the skin effect. Regards, Ing. Gert Gremmen g.grem...@cetest.nl mailto:g.grem...@cetest.nl www.cetest.nl Kiotoweg 363 3047 BG Rotterdam T 31(0)104152426 F 31(0)104154953 - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail
RE: [PSES] Discharge capacitors
Lightning detectors function (among other frequencies) down to 10 kHz. My opinion is that most of the lightning energy is below 1 MHz. Regards, Ing. Gert Gremmen g.grem...@cetest.nl mailto:g.grem...@cetest.nl www.cetest.nl Kiotoweg 363 3047 BG Rotterdam T 31(0)104152426 F 31(0)104154953 Before printing, think about the environment. Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens Fred Townsend Verzonden: Friday, November 06, 2009 11:52 AM Aan: m...@sfo.com CC: emc-pstc@LISTSERV.IEEE.ORG Onderwerp: Re: [PSES] Discharge capacitors Robert it is difficult to validate your models without knowing more about them but they are suspect when they fail to uphold empirically derived practice that has existed for longer than field solvers. You certainly stick your neck out when you say: CONCLUSION: Round is always better. I can think of numerous exceptions, exceptions that may prove the rule. In fairness many of the exceptions are caused effects not considered by your models but are real world, nevertheless. ( I thought this discussion was about best practice.) For instance if one is terminating in a, PCB or just a tab, round tube requires a round to rectangular conversion. How may that conversion effect corona? As you said nature doesn't like 'pointy' stuff. It would be folly to characterize the problem as purely one of inductance. We like to model lightning as pulse but we know lightning is often a damped sinusoid. Where does the sinusoid come from? We know that if hit a LC circuit with an impulse function, the circuit will ring at its natural frequency. Could this be the source of the sinusoid? If we suspect there are resonance effects, then clearly we must address capacitance and L/C ratios and transmission line effects as well. Clearly your 2D field solver isn't going to do that. Finally in your models, isn't there going to be significant energy below 10 MHz? My AM broadcast radio certainly thinks there is whenever lightning strikes nearby. Why do you show reactance for ribbon and resistance for tube? Is that an error of missing 'j's or is this truly apples and oranges? Best regards, Fred Townsend DC to Light m...@sfo.com wrote: Flat rectangular is NOT better than a round tube if each have the same circumference. The round tube has lower inductance than a flat ribbon conductor of comparable circumference. Makes sense, because Nature abhors 'pointy' stuff. This statement is based upon a comparison analyzing the two structures using finite element analysis, femm 4.2. Given: solid ribbon copper conductor, 1 inch wide and 120 mils thick copper tube, 0.75 inch outside diameter and 120 mils wall thickness The two circumferences are approximately the same. Rectangle 2 * (0.12+1) = 2.24 inches Tube pi * 0.7 = 2.20 inches Which is a better conductor? Assume infinitely long, straight conductors. Assuming most of lightning energy is significant between 1MHz to 100MHz, calculate each conductor's characteristics at 10MHz and at 100MHz using 2D finite element analysis. Method: place each conductor in a 24 inch diameter metal 'tube' to provide return current and represent infinity. Note: I also used single conductors in free space with current return at infinity. Values changed, but the conclusions did not change. Use a 12 inch length to reference values per ft. Mesh was set to be fine near the surfaces of the conductors, so that even with hgih frequency currents inside the conductors were accurately represented. Skin depth was more than 3 nodes. From results, the current as a function of depth into the conductors matched expected values. Plots of current/eddy currents verified mesh was of suficient density for these calculations. TABLE RESULTS: Ribbon - Solid mesh 69,406 10MHz 210 nH/ft 0.00347 W 13.2j ohm/ft 83 milliohm/ft 100MHz 210 nH/ft 0.0115W 132j ohm/ft0.15 ohm/ft Tube - Hollow mesh 90,233 100MHz 203 nH/ft 0.00239W 12.8 ohm/ft69 mOhm/ft 100MHz 203 nH/ft 0.00732 128 ohm/ft 0.12 ohm/ft It was interesting to note that with a wall thickness of more than 10 mils, at these frequencies the metal was doing nothing but physically supporting the outside layer. CONCLUSION: Round is always better. Robert As a rule of thumb, a conductor has an (self)inductance proportionally inverse with it's circumference (if fact the shortest way the magnetic field lines will take). Big flat conductors always perform better then round ones, as they have the highest circumference per kilo. Litz and silver(gold) coated conductors do contribute to the real part of the impedance (=resistance) properties only. Litz by increasing the conductive surfaces so reducing the resistance increase caused by the skin
Re: [PSES] Discharge capacitors
Robert it is difficult to validate your models without knowing more about them but they are suspect when they fail to uphold empirically derived practice that has existed for longer than field solvers. You certainly stick your neck out when you say: CONCLUSION: Round is always better. I can think of numerous exceptions, exceptions that may prove the rule. In fairness many of the exceptions are caused effects not considered by your models but are real world, nevertheless. ( I thought this discussion was about best practice.) For instance if one is terminating in a, PCB or just a tab, round tube requires a round to rectangular conversion. How may that conversion effect corona? As you said nature doesn't like 'pointy' stuff. It would be folly to characterize the problem as purely one of inductance. We like to model lightning as pulse but we know lightning is often a damped sinusoid. Where does the sinusoid come from? We know that if hit a LC circuit with an impulse function, the circuit will ring at its natural frequency. Could this be the source of the sinusoid? If we suspect there are resonance effects, then clearly we must address capacitance and L/C ratios and transmission line effects as well. Clearly your 2D field solver isn't going to do that. Finally in your models, isn't there going to be significant energy below 10 MHz? My AM broadcast radio certainly thinks there is whenever lightning strikes nearby. Why do you show reactance for ribbon and resistance for tube? Is that an error of missing 'j's or is this truly apples and oranges? Best regards, Fred Townsend DC to Light m...@sfo.com wrote: Flat rectangular is NOT better than a round tube if each have the same circumference. The round tube has lower inductance than a flat ribbon conductor of comparable circumference. Makes sense, because Nature abhors 'pointy' stuff. This statement is based upon a comparison analyzing the two structures using finite element analysis, femm 4.2. Given: solid ribbon copper conductor, 1 inch wide and 120 mils thick copper tube, 0.75 inch outside diameter and 120 mils wall thickness The two circumferences are approximately the same. Rectangle 2 * (0.12+1) = 2.24 inches Tube pi * 0.7 = 2.20 inches Which is a better conductor? Assume infinitely long, straight conductors. Assuming most of lightning energy is significant between 1MHz to 100MHz, calculate each conductor's characteristics at 10MHz and at 100MHz using 2D finite element analysis. Method: place each conductor in a 24 inch diameter metal 'tube' to provide return current and represent infinity. Note: I also used single conductors in free space with current return at infinity. Values changed, but the conclusions did not change. Use a 12 inch length to reference values per ft. Mesh was set to be fine near the surfaces of the conductors, so that even with hgih frequency currents inside the conductors were accurately represented. Skin depth was more than 3 nodes. From results, the current as a function of depth into the conductors matched expected values. Plots of current/eddy currents verified mesh was of suficient density for these calculations. TABLE RESULTS: Ribbon - Solid mesh 69,406 10MHz 210 nH/ft 0.00347 W 13.2j ohm/ft83 milliohm/ft 100MHz 210 nH/ft 0.0115W 132j ohm/ft 0.15 ohm/ft Tube - Hollow mesh 90,233 100MHz 203 nH/ft 0.00239W 12.8 ohm/ft 69 mOhm/ft 100MHz 203 nH/ft 0.00732 128 ohm/ft 0.12 ohm/ft It was interesting to note that with a wall thickness of more than 10 mils, at these frequencies the metal was doing nothing but physically supporting the outside layer. CONCLUSION: Round is always better. Robert As a rule of thumb, a conductor has an (self)inductance proportionally inverse with it's circumference (if fact the shortest way the magnetic field lines will take). Big flat conductors always perform better then round ones, as they have the highest circumference per kilo. Litz and silver(gold) coated conductors do contribute to the real part of the impedance (=resistance) properties only. Litz by increasing the conductive surfaces so reducing the
Re: [PSES] Discharge capacitors
In message 1937.66.81.215.25.1257470854.squir...@cp01.sfo.com, dated Thu, 5 Nov 2009, m...@sfo.com writes: solid ribbon copper conductor, 1 inch wide and 120 mils thick copper tube, 0.75 inch outside diameter and 120 mils wall thickness The two circumferences are approximately the same. Rectangle 2 * (0.12+1) = 2.24 inches Tube pi * 0.7 = 2.20 inches Why 0.7? The OD is 0.75, giving a circumference of 2.36 inches. Also, the criterion used to claim that flat is better is 'circumference per kilo(gram)'. What are the lineal densities of your example conductors? -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK Help stamp out intolerance! - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Discharge capacitors
The setup is rather artificial in that it compares isolated conductors. The situation flips around for proximal conductors due to proximity effect. Try modeling a coil with a foil winding versus round wire. Flat adjacent surfaces perform better than adjacent round ones because the current bunching is less pronounced in the foil. Also note the huge difference in area efficiency. As you mentioned, for small skin depth compared to diameter most circular cross sectional area is electrically wasted. Foil of suitable thickness (not too thin and not too thick for the frequency of interest) will carry current throughout the entire cross section, although there will be higher current density at the foil edges than down the center. Round is not a panacea, and in certain situations can be distinctly inferior. Orin Laney On Thu, 5 Nov 2009 17:27:34 -0800 Robert Macy m...@sfo.com writes: Flat rectangular is NOT better than a round tube if each have the same circumference. The round tube has lower inductance than a flat ribbon conductor of comparable circumference. Makes sense, because Nature abhors 'pointy' stuff. This statement is based upon a comparison analyzing the two structures using finite element analysis, femm 4.2. Given: solid ribbon copper conductor, 1 inch wide and 120 mils thick copper tube, 0.75 inch outside diameter and 120 mils wall thickness The two circumferences are approximately the same. Rectangle 2 * (0.12+1) = 2.24 inches Tube pi * 0.7 = 2.20 inches Which is a better conductor? Assume infinitely long, straight conductors. Assuming most of lightning energy is significant between 1MHz to 100MHz, calculate each conductor's characteristics at 10MHz and at 100MHz using 2D finite element analysis. Method: place each conductor in a 24 inch diameter metal 'tube' to provide return current and represent infinity. Note: I also used single conductors in free space with current return at infinity. Values changed, but the conclusions did not change. Use a 12 inch length to reference values per ft. Mesh was set to be fine near the surfaces of the conductors, so that even with hgih frequency currents inside the conductors were accurately represented. Skin depth was more than 3 nodes. From results, the current as a function of depth into the conductors matched expected values. Plots of current/eddy currents verified mesh was of suficient density for these calculations. TABLE RESULTS: Ribbon - Solid mesh 69,406 10MHz210 nH/ft0.00347 W 13.2j ohm/ft 83 milliohm/ft 100MHz210 nH/ft0.0115W 132j ohm/ft0.15 ohm/ft Tube - Hollowmesh 90,233 100MHz203 nH/ft0.00239W 12.8 ohm/ft69 mOhm/ft 100MHz203 nH/ft0.00732 128 ohm/ft0.12 ohm/ft It was interesting to note that with a wall thickness of more than 10 mils, at these frequencies the metal was doing nothing but physically supporting the outside layer. CONCLUSION: Round is always better. Robert As a rule of thumb, a conductor has an (self)inductance proportionally inverse with it's circumference (if fact the shortest way the magnetic field lines will take). Big flat conductors always perform better then round ones, as they have the highest circumference per kilo. Litz and silver(gold) coated conductors do contribute to the real part of the impedance (=resistance) properties only. Litz by increasing the conductive surfaces so reducing the resistance increase caused by the skin effect. Regards, Ing. Gert Gremmen g.grem...@cetest.nl mailto:g.grem...@cetest.nl www.cetest.nl Kiotoweg 363 3047 BG Rotterdam T 31(0)104152426 F 31(0)104154953 - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - 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 emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats),
RE: [PSES] Discharge capacitors
Flat rectangular is NOT better than a round tube if each have the same circumference. The round tube has lower inductance than a flat ribbon conductor of comparable circumference. Makes sense, because Nature abhors 'pointy' stuff. This statement is based upon a comparison analyzing the two structures using finite element analysis, femm 4.2. Given: solid ribbon copper conductor, 1 inch wide and 120 mils thick copper tube, 0.75 inch outside diameter and 120 mils wall thickness The two circumferences are approximately the same. Rectangle 2 * (0.12+1) = 2.24 inches Tube pi * 0.7 = 2.20 inches Which is a better conductor? Assume infinitely long, straight conductors. Assuming most of lightning energy is significant between 1MHz to 100MHz, calculate each conductor's characteristics at 10MHz and at 100MHz using 2D finite element analysis. Method: place each conductor in a 24 inch diameter metal 'tube' to provide return current and represent infinity. Note: I also used single conductors in free space with current return at infinity. Values changed, but the conclusions did not change. Use a 12 inch length to reference values per ft. Mesh was set to be fine near the surfaces of the conductors, so that even with hgih frequency currents inside the conductors were accurately represented. Skin depth was more than 3 nodes. From results, the current as a function of depth into the conductors matched expected values. Plots of current/eddy currents verified mesh was of suficient density for these calculations. TABLE RESULTS: Ribbon - Solid mesh 69,406 10MHz 210 nH/ft 0.00347 W 13.2j ohm/ft83 milliohm/ft 100MHz 210 nH/ft 0.0115W 132j ohm/ft 0.15 ohm/ft Tube - Hollow mesh 90,233 100MHz 203 nH/ft 0.00239W 12.8 ohm/ft 69 mOhm/ft 100MHz 203 nH/ft 0.00732 128 ohm/ft 0.12 ohm/ft It was interesting to note that with a wall thickness of more than 10 mils, at these frequencies the metal was doing nothing but physically supporting the outside layer. CONCLUSION: Round is always better. Robert As a rule of thumb, a conductor has an (self)inductance proportionally inverse with it's circumference (if fact the shortest way the magnetic field lines will take). Big flat conductors always perform better then round ones, as they have the highest circumference per kilo. Litz and silver(gold) coated conductors do contribute to the real part of the impedance (=resistance) properties only. Litz by increasing the conductive surfaces so reducing the resistance increase caused by the skin effect. Regards, Ing. Gert Gremmen g.grem...@cetest.nl mailto:g.grem...@cetest.nl www.cetest.nl Kiotoweg 363 3047 BG Rotterdam T 31(0)104152426 F 31(0)104154953 - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Discharge capacitors
In message 009901ca5e08$2fe497e0$8fadc7a0$@mcauley, dated Thu, 5 Nov 2009, John McAuley john.mcau...@cei.ie writes: Having mentioned using a defibrillator, I wonder what they use to dump the charge? An SCR presumably. No, the patient. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK Help stamp out intolerance! - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] Discharge capacitors
Hi Oran I have checked a couple of defibrillators. They do not use the 32 µF capacitor. Also the circuit recommends certain series resistor values. Having mentioned using a defibrillator, I wonder what they use to dump the charge? An SCR presumably. BR John DISCLAIMER: The information contained in this e-mail may be confidential and is intended solely for the use of the named addressee. Access, copying or re-use of the e-mail or any information contained therein by any other person is not authorised. If you are not the intended recipient please notify us immediately by returning the e-mail to the originator From: ola...@juno.com [mailto:ola...@juno.com] Sent: 04 November 2009 20:31 To: john.mcau...@cei.ie Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors You can get SCRs up to 7KV withstand, or you can stack them to get the voltage rating if you do it right. The critical parameters are maximum rate of current rise and peak current capability. In general, you'd want an SCR rated for inverter duty as these are much faster than the ordinary phase control variety. Still, you will be working in microseconds, not nanoseconds. Spark gaps and electromechanical switches are clumsy devices, but still can't be beat for abrupt risetimes at very large power levels. I'm wondering if there is a mercury contactor rated for your voltage requirement. Also, perhaps instead of simulating a defibrillator you could use a real one. I've seen used ones. Orin Laney On Wed, 4 Nov 2009 19:15:20 - John McAuley john.mcau...@cei.ie writes: On a related subject, what do you use for the switch in these surge generators? I have seen electro mechanical switches and I believe some of them use SCRs? Is there a readily available high voltage switch that can do it? We have a need to test a medical device using a 32 µF cap charged to 5000V for one of the 60601 standards to simulate a defibrillator. We were going to modify an old Haefely P6T. Regards John DISCLAIMER: The information contained in this e-mail may be confidential and is intended solely for the use of the named addressee. Access, copying or re-use of the e-mail or any information contained therein by any other person is not authorised. If you are not the intended recipient please notify us immediately by returning the e-mail to the originator -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Brian O'Connell Sent: 04 November 2009 18:43 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Discharge capacitors For this particular application, how does the ribbon stuff compares to braided ground straps? I am about to build something similar, and would like to know if someone has already experimented with this. thanks, Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Fred Townsend Sent: Wednesday, November 04, 2009 10:36 AM To: ola...@juno.com Cc: lfresea...@aol.com; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors Derek : I think Orin offers good advice. You also need to pay attention to your network geometry. i.e. Inductance is your enemy. Two 10 uF caps in parallel are better than one 20 uF. Straight runs of ribbon wire are better than coils of round wire. Regards, Fred Townsend DC to Light ola...@juno.com wrote: The usual suspects are NWL in North Carolina, CSI in California, and General Atomics (formerly Maxwell). They all know what they are doing and have low inductance pulse rated caps capable of multi-kiloamp discharge peaks. Orin Laney / Atwood Research On Wed, 4 Nov 2009 11:04:51 -0500 lfresea...@aol.com writes: Good morning folks, I have been working on improving the quality of my lightning simulator and have come to the conclusion that I need better capacitors. Can anyone share their opinions on manufacturers and/or models that are appropriate. An offline response may be appropriate. Sincerely, Derek Walton L F Research - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] Discharge capacitors
As a rule of thumb, a conductor has an (self)inductance proportionally inverse with it’s circumference (if fact the shortest way the magnetic field lines will take). Big flat conductors always perform better then round ones, as they have the highest circumference per kilo. Litz and silver(gold) coated conductors do contribute to the real part of the impedance (=resistance) properties only. Litz by increasing the conductive surfaces so reducing the resistance increase caused by the skin effect. Regards, Ing. Gert Gremmen g.grem...@cetest.nl mailto:g.grem...@cetest.nl www.cetest.nl Kiotoweg 363 3047 BG Rotterdam T 31(0)104152426 F 31(0)104154953 Before printing, think about the environment. Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens Fred Townsend Verzonden: Wednesday, November 04, 2009 11:02 PM Aan: m...@sfo.com CC: emc-pstc@LISTSERV.IEEE.ORG Onderwerp: Re: [PSES] Discharge capacitors Is this right? Not necessarily. Braid may or may not be hollow. Look at the braid frequently used for the battery ground lead on automobiles. Braid is frequently used for bonding large metals parts such as engine to body on your car. The ribbon referenced here is a single conductor. Sometimes I make them from sheets of copper or brass. They are not normally used where the environment contains motion or vibration. However they are ideal for making a mobius loop to non inductively feed the cathode of a high power transmitting tube. The term ribbon is not distinct and may include braided ribbons. m...@sfo.com wrote: It is my understanding that the following terms apply. If not, please elaborate/correct. Braid - bare small gauge wires woven into a general hollow tube shape, intended to be used as shielding Ribbon - flat shape, multiple conductors insulated from each other, solid or [7? wires bare fibre wires?] to make each conductor. Solid Ribbon - flat shape, multiple conductors insulated from each other, solid wire conductors. Is this right? Robert Brian: I include braid in the category of ribbon without distinction. However braid is superior to solid ribbon for most applications because it is easier to work with. i.e. when connecting braid to a screw terminal I spread the braid out and slip the screw between (with flat or star washer) strands. It also has lower skin effect at RF frequencies. Solid ribbon must be crimped, drilled, or punched for screw terminals. The exception is solid ribbon is superior when using mobius loops. Silver braid is superior for RF but needs to be protected from corrosion to stay effective. I use ordinary tined braid for pulse generators. Regards, Fred Townsend Brian O'Connell wrote: For this particular application, how does the ribbon stuff compares to braided ground straps? I am about to build something similar, and would like to know if someone has already experimented with this. thanks, Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Fred Townsend Sent: Wednesday, November 04, 2009 10:36 AM To: ola...@juno.com Cc: lfresea...@aol.com; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors Derek : I think Orin offers good advice. You also need to pay attention to your network geometry. i.e. Inductance is your enemy. Two 10 uF caps in parallel are better than one 20 uF. Straight runs of ribbon wire are better than coils of round wire. Regards, Fred Townsend DC to Light ola...@juno.com wrote: The usual suspects are NWL in North Carolina, CSI in California, and General Atomics (formerly Maxwell). They all know what they are doing and have low inductance pulse rated caps capable of multi-kiloamp discharge peaks. Orin Laney / Atwood Research On Wed, 4 Nov 2009 11:04:51 -0500 lfresea...@aol.com writes: Good morning folks, I have been working on improving the quality of my lightning simulator and have come to the conclusion that I need better capacitors. Can anyone share their opinions on manufacturers and/or models that are appropriate. An offline response
Re: [PSES] Discharge capacitors
In message 4af206be.8080...@skyskan.com, dated Wed, 4 Nov 2009, Mike Mertinooke mertino...@skyskan.com writes: How would you classify Litz wire? As expensive? It doesn't have any low-inductance properties. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK Help stamp out intolerance! - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Discharge capacitors
How would you classify Litz wire? Fred Townsend wrote: Is this right? Not necessarily. Braid may or may not be hollow. Look at the braid frequently used for the battery ground lead on automobiles. Braid is frequently used for bonding large metals parts such as engine to body on your car. The ribbon referenced here is a single conductor. Sometimes I make them from sheets of copper or brass. They are not normally used where the environment contains motion or vibration. However they are ideal for making a mobius loop to non inductively feed the cathode of a high power transmitting tube. The term ribbon is not distinct and may include braided ribbons. m...@sfo.com wrote: It is my understanding that the following terms apply. If not, please elaborate/correct. Braid - bare small gauge wires woven into a general hollow tube shape, intended to be used as shielding Ribbon - flat shape, multiple conductors insulated from each other, solid or [7? wires bare fibre wires?] to make each conductor. Solid Ribbon - flat shape, multiple conductors insulated from each other, solid wire conductors. Is this right? Robert Brian: I include braid in the category of ribbon without distinction. However braid is superior to solid ribbon for most applications because it is easier to work with. i.e. when connecting braid to a screw terminal I spread the braid out and slip the screw between (with flat or star washer) strands. It also has lower skin effect at RF frequencies. Solid ribbon must be crimped, drilled, or punched for screw terminals. The exception is solid ribbon is superior when using mobius loops. Silver braid is superior for RF but needs to be protected from corrosion to stay effective. I use ordinary tined braid for pulse generators. Regards, Fred Townsend Brian O'Connell wrote: For this particular application, how does the ribbon stuff compares to braided ground straps? I am about to build something similar, and would like to know if someone has already experimented with this. thanks, Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Fred Townsend Sent: Wednesday, November 04, 2009 10:36 AM To: ola...@juno.com Cc: lfresea...@aol.com; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors Derek : I think Orin offers good advice. You also need to pay attention to your network geometry. i.e. Inductance is your enemy. Two 10 uF caps in parallel are better than one 20 uF. Straight runs of ribbon wire are better than coils of round wire. Regards, Fred Townsend DC to Light ola...@juno.com wrote: The usual suspects are NWL in North Carolina, CSI in California, and General Atomics (formerly Maxwell). They all know what they are doing and have low inductance pulse rated caps capable of multi-kiloamp discharge peaks. Orin Laney / Atwood Research On Wed, 4 Nov 2009 11:04:51 -0500 lfresea...@aol.com writes: Good morning folks
Re: [PSES] Discharge capacitors OT
Mike Mertinooke wrote: How would you classify Litz wire? I'd classify Litz wire as off topic. It has a bandwidth of about 10 MHz (as the text books say... the proof will be left to the reader). The low bandwidth makes it poor for pulses and it doesn't handle high current surges well either. It's expensive and takes special training to utilize. Other than that, how was your evening Mrs. Lincoln? Fred Townsend DC to Light Fred Townsend wrote: Is this right? Not necessarily. Braid may or may not be hollow. Look at the braid frequently used for the battery ground lead on automobiles. Braid is frequently used for bonding large metals parts such as engine to body on your car. The ribbon referenced here is a single conductor. Sometimes I make them from sheets of copper or brass. They are not normally used where the environment contains motion or vibration. However they are ideal for making a mobius loop to non inductively feed the cathode of a high power transmitting tube. The term ribbon is not distinct and may include braided ribbons. m...@sfo.com wrote: It is my understanding that the following terms apply. If not, please elaborate/correct. Braid - bare small gauge wires woven into a general hollow tube shape, intended to be used as shielding Ribbon - flat shape, multiple conductors insulated from each other, solid or [7? wires bare fibre wires?] to make each conductor. Solid Ribbon - flat shape, multiple conductors insulated from each other, solid wire conductors. Is this right? Robert Brian: I include braid in the category of ribbon without distinction. However braid is superior to solid ribbon for most applications because it is easier to work with. i.e. when connecting braid to a screw terminal I spread the braid out and slip the screw between (with flat or star washer) strands. It also has lower skin effect at RF frequencies. Solid ribbon must be crimped, drilled, or punched for screw terminals. The exception is solid ribbon is superior when using mobius loops. Silver braid is superior for RF but needs to be protected from corrosion to stay effective. I use ordinary tined braid for pulse generators. Regards, Fred Townsend Brian O'Connell wrote: For this particular application, how does the ribbon stuff compares to braided ground straps? I am about to build something similar, and would like to know if someone has already experimented with this. thanks, Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Fred Townsend Sent: Wednesday, November 04, 2009 10:36 AM To: ola...@juno.com Cc: lfresea...@aol.com; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors Derek : I think Orin offers good advice. You also need to pay attention to your network geometry. i.e. Inductance is your enemy. Two 10 uF caps in parallel are better than one 20 uF. Straight runs
Re: [PSES] Discharge capacitors
Is this right? Not necessarily. Braid may or may not be hollow. Look at the braid frequently used for the battery ground lead on automobiles. Braid is frequently used for bonding large metals parts such as engine to body on your car. The ribbon referenced here is a single conductor. Sometimes I make them from sheets of copper or brass. They are not normally used where the environment contains motion or vibration. However they are ideal for making a mobius loop to non inductively feed the cathode of a high power transmitting tube. The term ribbon is not distinct and may include braided ribbons. m...@sfo.com wrote: It is my understanding that the following terms apply. If not, please elaborate/correct. Braid - bare small gauge wires woven into a general hollow tube shape, intended to be used as shielding Ribbon - flat shape, multiple conductors insulated from each other, solid or [7? wires bare fibre wires?] to make each conductor. Solid Ribbon - flat shape, multiple conductors insulated from each other, solid wire conductors. Is this right? Robert Brian: I include braid in the category of ribbon without distinction. However braid is superior to solid ribbon for most applications because it is easier to work with. i.e. when connecting braid to a screw terminal I spread the braid out and slip the screw between (with flat or star washer) strands. It also has lower skin effect at RF frequencies. Solid ribbon must be crimped, drilled, or punched for screw terminals. The exception is solid ribbon is superior when using mobius loops. Silver braid is superior for RF but needs to be protected from corrosion to stay effective. I use ordinary tined braid for pulse generators. Regards, Fred Townsend Brian O'Connell wrote: For this particular application, how does the ribbon stuff compares to braided ground straps? I am about to build something similar, and would like to know if someone has already experimented with this. thanks, Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Fred Townsend Sent: Wednesday, November 04, 2009 10:36 AM To: ola...@juno.com Cc: lfresea...@aol.com; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors Derek : I think Orin offers good advice. You also need to pay attention to your network geometry. i.e. Inductance is your enemy. Two 10 uF caps in parallel are better than one 20 uF. Straight runs of ribbon wire are better than coils of round wire. Regards, Fred Townsend DC to Light ola...@juno.com wrote: The usual suspects are NWL in North Carolina, CSI in California, and General Atomics (formerly Maxwell). They all know what they are doing and have low inductance pulse rated caps capable of multi-kiloamp discharge peaks. Orin Laney / Atwood Research On Wed, 4 Nov 2009 11:04:51 -0500 lfresea...@aol.com writes: Good morning folks, I have been working on improving the quality of my lightning simulator and have come to the conclusion that I need better capacitors. Can anyone share their opinions on manufacturers and/or models that are appropriate. An offline response may be appropriate. Sincerely, Derek Walton L F Research - This message is from the IEEE Product
Re: [PSES] Discharge capacitors
Actually, no. The braid definition works, but ribbon cable, which indeed has separate conductors, should not be confused with ribbon shaped single conductors like flat magnet wire or the ribbon bond wires used for MMICs and certain other RF devices. In other words, ribbon is a general shape. It is true that there are varieties of ribbon cable based on ribbon conductors, in addition to the ordinary stuff. Orin Laney On Wed, 4 Nov 2009 13:37:46 -0800 Robert Macy m...@sfo.com writes: It is my understanding that the following terms apply. If not, please elaborate/correct. Braid - bare small gauge wires woven into a general hollow tube shape, intended to be used as shielding Ribbon - flat shape, multiple conductors insulated from each other, solid or [7? wires bare fibre wires?] to make each conductor. Solid Ribbon - flat shape, multiple conductors insulated from each other, solid wire conductors. Is this right? Robert Brian: I include braid in the category of ribbon without distinction. However braid is superior to solid ribbon for most applications because it is easier to work with. i.e. when connecting braid to a screw terminal I spread the braid out and slip the screw between (with flat or star washer) strands. It also has lower skin effect at RF frequencies. Solid ribbon must be crimped, drilled, or punched for screw terminals. The exception is solid ribbon is superior when using mobius loops. Silver braid is superior for RF but needs to be protected from corrosion to stay effective. I use ordinary tined braid for pulse generators. Regards, Fred Townsend Brian O'Connell wrote: For this particular application, how does the ribbon stuff compares to braided ground straps? I am about to build something similar, and would like to know if someone has already experimented with this. thanks, Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Fred Townsend Sent: Wednesday, November 04, 2009 10:36 AM To: ola...@juno.com Cc: lfresea...@aol.com; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors Derek : I think Orin offers good advice. You also need to pay attention to your network geometry. i.e. Inductance is your enemy. Two 10 uF caps in parallel are better than one 20 uF. Straight runs of ribbon wire are better than coils of round wire. Regards, Fred Townsend DC to Light ola...@juno.com wrote: The usual suspects are NWL in North Carolina, CSI in California, and General Atomics (formerly Maxwell). They all know what they are doing and have low inductance pulse rated caps capable of multi-kiloamp discharge peaks. Orin Laney / Atwood Research On Wed, 4 Nov 2009 11:04:51 -0500 lfresea...@aol.com writes: Good morning folks, I have been working on improving the quality of my lightning simulator and have come to the conclusion that I need better capacitors. Can anyone share their opinions on manufacturers and/or models that are appropriate. An offline response may be appropriate. Sincerely, Derek Walton L F Research - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Discharge capacitors
It is my understanding that the following terms apply. If not, please elaborate/correct. Braid - bare small gauge wires woven into a general hollow tube shape, intended to be used as shielding Ribbon - flat shape, multiple conductors insulated from each other, solid or [7? wires bare fibre wires?] to make each conductor. Solid Ribbon - flat shape, multiple conductors insulated from each other, solid wire conductors. Is this right? Robert Brian: I include braid in the category of ribbon without distinction. However braid is superior to solid ribbon for most applications because it is easier to work with. i.e. when connecting braid to a screw terminal I spread the braid out and slip the screw between (with flat or star washer) strands. It also has lower skin effect at RF frequencies. Solid ribbon must be crimped, drilled, or punched for screw terminals. The exception is solid ribbon is superior when using mobius loops. Silver braid is superior for RF but needs to be protected from corrosion to stay effective. I use ordinary tined braid for pulse generators. Regards, Fred Townsend Brian O'Connell wrote: For this particular application, how does the ribbon stuff compares to braided ground straps? I am about to build something similar, and would like to know if someone has already experimented with this. thanks, Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Fred Townsend Sent: Wednesday, November 04, 2009 10:36 AM To: ola...@juno.com Cc: lfresea...@aol.com; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors Derek : I think Orin offers good advice. You also need to pay attention to your network geometry. i.e. Inductance is your enemy. Two 10 uF caps in parallel are better than one 20 uF. Straight runs of ribbon wire are better than coils of round wire. Regards, Fred Townsend DC to Light ola...@juno.com wrote: The usual suspects are NWL in North Carolina, CSI in California, and General Atomics (formerly Maxwell). They all know what they are doing and have low inductance pulse rated caps capable of multi-kiloamp discharge peaks. Orin Laney / Atwood Research On Wed, 4 Nov 2009 11:04:51 -0500 lfresea...@aol.com writes: Good morning folks, I have been working on improving the quality of my lightning simulator and have come to the conclusion that I need better capacitors. Can anyone share their opinions on manufacturers and/or models that are appropriate. An offline response may be appropriate. Sincerely, Derek Walton L F Research - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] Discharge capacitors
Good point about the defib - note the 'public' defibs that are intended for use by common guy on an airplane or business office. According to the compliance guy that works down the street from me (at a large biomed company), they bought a box-full and modified the caps. Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of ola...@juno.com Sent: Wednesday, November 04, 2009 12:31 PM To: john.mcau...@cei.ie Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors You can get SCRs up to 7KV withstand, or you can stack them to get the voltage rating if you do it right. The critical parameters are maximum rate of current rise and peak current capability. In general, you'd want an SCR rated for inverter duty as these are much faster than the ordinary phase control variety. Still, you will be working in microseconds, not nanoseconds. Spark gaps and electromechanical switches are clumsy devices, but still can't be beat for abrupt risetimes at very large power levels. I'm wondering if there is a mercury contactor rated for your voltage requirement. Also, perhaps instead of simulating a defibrillator you could use a real one. I've seen used ones. Orin Laney - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Discharge capacitors
You can get SCRs up to 7KV withstand, or you can stack them to get the voltage rating if you do it right. The critical parameters are maximum rate of current rise and peak current capability. In general, you'd want an SCR rated for inverter duty as these are much faster than the ordinary phase control variety. Still, you will be working in microseconds, not nanoseconds. Spark gaps and electromechanical switches are clumsy devices, but still can't be beat for abrupt risetimes at very large power levels. I'm wondering if there is a mercury contactor rated for your voltage requirement. Also, perhaps instead of simulating a defibrillator you could use a real one. I've seen used ones. Orin Laney On Wed, 4 Nov 2009 19:15:20 - John McAuley john.mcau...@cei.ie writes: On a related subject, what do you use for the switch in these surge generators? I have seen electro mechanical switches and I believe some of them use SCRs? Is there a readily available high voltage switch that can do it? We have a need to test a medical device using a 32 µF cap charged to 5000V for one of the 60601 standards to simulate a defibrillator. We were going to modify an old Haefely P6T. Regards John DISCLAIMER: The information contained in this e-mail may be confidential and is intended solely for the use of the named addressee. Access, copying or re-use of the e-mail or any information contained therein by any other person is not authorised. If you are not the intended recipient please notify us immediately by returning the e-mail to the originator -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Brian O'Connell Sent: 04 November 2009 18:43 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Discharge capacitors For this particular application, how does the ribbon stuff compares to braided ground straps? I am about to build something similar, and would like to know if someone has already experimented with this. thanks, Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Fred Townsend Sent: Wednesday, November 04, 2009 10:36 AM To: ola...@juno.com Cc: lfresea...@aol.com; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors Derek : I think Orin offers good advice. You also need to pay attention to your network geometry. i.e. Inductance is your enemy. Two 10 uF caps in parallel are better than one 20 uF. Straight runs of ribbon wire are better than coils of round wire. Regards, Fred Townsend DC to Light ola...@juno.com wrote: The usual suspects are NWL in North Carolina, CSI in California, and General Atomics (formerly Maxwell). They all know what they are doing and have low inductance pulse rated caps capable of multi-kiloamp discharge peaks. Orin Laney / Atwood Research On Wed, 4 Nov 2009 11:04:51 -0500 lfresea...@aol.com writes: Good morning folks, I have been working on improving the quality of my lightning simulator and have come to the conclusion that I need better capacitors. Can anyone share their opinions on manufacturers and/or models that are appropriate. An offline response may be appropriate. Sincerely, Derek Walton L F Research - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering
Re: [PSES] Discharge capacitors
In message 4af1d2cf.40...@sbcglobal.net, dated Wed, 4 Nov 2009, Fred Townsend ftowns...@sbcglobal.net writes: Silver braid is superior for RF but needs to be protected from corrosion to stay effective. Have the audiophool suppliers missed out on supplying gold-plated braid? -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK Help stamp out intolerance! - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Discharge capacitors
Brian: I include braid in the category of ribbon without distinction. However braid is superior to solid ribbon for most applications because it is easier to work with. i.e. when connecting braid to a screw terminal I spread the braid out and slip the screw between (with flat or star washer) strands. It also has lower skin effect at RF frequencies. Solid ribbon must be crimped, drilled, or punched for screw terminals. The exception is solid ribbon is superior when using mobius loops. Silver braid is superior for RF but needs to be protected from corrosion to stay effective. I use ordinary tined braid for pulse generators. Regards, Fred Townsend Brian O'Connell wrote: For this particular application, how does the ribbon stuff compares to braided ground straps? I am about to build something similar, and would like to know if someone has already experimented with this. thanks, Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Fred Townsend Sent: Wednesday, November 04, 2009 10:36 AM To: ola...@juno.com Cc: lfresea...@aol.com; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors Derek : I think Orin offers good advice. You also need to pay attention to your network geometry. i.e. Inductance is your enemy. Two 10 uF caps in parallel are better than one 20 uF. Straight runs of ribbon wire are better than coils of round wire. Regards, Fred Townsend DC to Light ola...@juno.com wrote: The usual suspects are NWL in North Carolina, CSI in California, and General Atomics (formerly Maxwell). They all know what they are doing and have low inductance pulse rated caps capable of multi-kiloamp discharge peaks. Orin Laney / Atwood Research On Wed, 4 Nov 2009 11:04:51 -0500 lfresea...@aol.com writes: Good morning folks, I have been working on improving the quality of my lightning simulator and have come to the conclusion that I need better capacitors. Can anyone share their opinions on manufacturers and/or models that are appropriate. An offline response may be appropriate. Sincerely, Derek Walton L F Research - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] Discharge capacitors
On a related subject, what do you use for the switch in these surge generators? I have seen electro mechanical switches and I believe some of them use SCRs? Is there a readily available high voltage switch that can do it? We have a need to test a medical device using a 32 µF cap charged to 5000V for one of the 60601 standards to simulate a defibrillator. We were going to modify an old Haefely P6T. Regards John DISCLAIMER: The information contained in this e-mail may be confidential and is intended solely for the use of the named addressee. Access, copying or re-use of the e-mail or any information contained therein by any other person is not authorised. If you are not the intended recipient please notify us immediately by returning the e-mail to the originator From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Brian O'Connell Sent: 04 November 2009 18:43 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Discharge capacitors For this particular application, how does the ribbon stuff compares to braided ground straps? I am about to build something similar, and would like to know if someone has already experimented with this. thanks, Brian From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Fred Townsend Sent: Wednesday, November 04, 2009 10:36 AM To: ola...@juno.com Cc: lfresea...@aol.com; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors Derek : I think Orin offers good advice. You also need to pay attention to your network geometry. i.e. Inductance is your enemy. Two 10 uF caps in parallel are better than one 20 uF. Straight runs of ribbon wire are better than coils of round wire. Regards, Fred Townsend DC to Light ola...@juno.com wrote: The usual suspects are NWL in North Carolina, CSI in California, and General Atomics (formerly Maxwell). They all know what they are doing and have low inductance pulse rated caps capable of multi-kiloamp discharge peaks. Orin Laney / Atwood Research On Wed, 4 Nov 2009 11:04:51 -0500 lfresea...@aol.com writes: Good morning folks, I have been working on improving the quality of my lightning simulator and have come to the conclusion that I need better capacitors. Can anyone share their opinions on manufacturers and/or models that are appropriate. An offline response may be appropriate. Sincerely, Derek Walton L F Research - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] Discharge capacitors
For pulse networks, you should be using the least inductive connections you can create. Unless you are making slow waveforms with rise/fall times greater than a micro second or so, you should be using striplines. Copper or brass, as wide and as short as creepage/clearance considerations allow. Be sure all edges are smooth, clean, and radiused to help prevent arcing. Even the 1.2/50 combination wave generators benefit from minimizing internal inductance. As mentioned, connecting several caps in parallel produces better results than using a single cap. Use non-inductive resistors for the pulse-shaping circuits. Keep the whole circuit as compact as you can. Regards, David Raynes Senior EMC Technologist National Technical Systems Inc. 5151 - 47th Street N.E. Calgary, Alberta Canada T3J 3R2 1-403-568-6605 x227 Fax: 1-403-568-6970 david.ray...@ntscorp.com From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Brian O'Connell Sent: Wednesday, November 04, 2009 11:43 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Discharge capacitors For this particular application, how does the ribbon stuff compares to braided ground straps? I am about to build something similar, and would like to know if someone has already experimented with this. thanks, Brian From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Fred Townsend Sent: Wednesday, November 04, 2009 10:36 AM To: ola...@juno.com Cc: lfresea...@aol.com; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors Derek : I think Orin offers good advice. You also need to pay attention to your network geometry. i.e. Inductance is your enemy. Two 10 uF caps in parallel are better than one 20 uF. Straight runs of ribbon wire are better than coils of round wire. Regards, Fred Townsend DC to Light ola...@juno.com wrote: The usual suspects are NWL in North Carolina, CSI in California, and General Atomics (formerly Maxwell). They all know what they are doing and have low inductance pulse rated caps capable of multi-kiloamp discharge peaks. Orin Laney / Atwood Research On Wed, 4 Nov 2009 11:04:51 -0500 lfresea...@aol.com writes: Good morning folks, I have been working on improving the quality of my lightning simulator and have come to the conclusion that I need better capacitors. Can anyone share their opinions on manufacturers and/or models that are appropriate. An offline response may be appropriate. Sincerely, Derek Walton L F Research - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] Discharge capacitors
For this particular application, how does the ribbon stuff compares to braided ground straps? I am about to build something similar, and would like to know if someone has already experimented with this. thanks, Brian From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Fred Townsend Sent: Wednesday, November 04, 2009 10:36 AM To: ola...@juno.com Cc: lfresea...@aol.com; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Discharge capacitors Derek : I think Orin offers good advice. You also need to pay attention to your network geometry. i.e. Inductance is your enemy. Two 10 uF caps in parallel are better than one 20 uF. Straight runs of ribbon wire are better than coils of round wire. Regards, Fred Townsend DC to Light ola...@juno.com wrote: The usual suspects are NWL in North Carolina, CSI in California, and General Atomics (formerly Maxwell). They all know what they are doing and have low inductance pulse rated caps capable of multi-kiloamp discharge peaks. Orin Laney / Atwood Research On Wed, 4 Nov 2009 11:04:51 -0500 lfresea...@aol.com writes: Good morning folks, I have been working on improving the quality of my lightning simulator and have come to the conclusion that I need better capacitors. Can anyone share their opinions on manufacturers and/or models that are appropriate. An offline response may be appropriate. Sincerely, Derek Walton L F Research - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Discharge capacitors
Derek : I think Orin offers good advice. You also need to pay attention to your network geometry. i.e. Inductance is your enemy. Two 10 uF caps in parallel are better than one 20 uF. Straight runs of ribbon wire are better than coils of round wire. Regards, Fred Townsend DC to Light ola...@juno.com wrote: The usual suspects are NWL in North Carolina, CSI in California, and General Atomics (formerly Maxwell). They all know what they are doing and have low inductance pulse rated caps capable of multi-kiloamp discharge peaks. Orin Laney / Atwood Research On Wed, 4 Nov 2009 11:04:51 -0500 lfresea...@aol.com writes: Good morning folks, I have been working on improving the quality of my lightning simulator and have come to the conclusion that I need better capacitors. Can anyone share their opinions on manufacturers and/or models that are appropriate. An offline response may be appropriate. Sincerely, Derek Walton L F Research - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org David Heald dhe...@gmail.com - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org David Heald dhe...@gmail.com - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org David Heald dhe...@gmail.com
Re: [PSES] Discharge capacitors
The usual suspects are NWL in North Carolina, CSI in California, and General Atomics (formerly Maxwell). They all know what they are doing and have low inductance pulse rated caps capable of multi-kiloamp discharge peaks. Orin Laney / Atwood Research On Wed, 4 Nov 2009 11:04:51 -0500 lfresea...@aol.com writes: Good morning folks, I have been working on improving the quality of my lightning simulator and have come to the conclusion that I need better capacitors. Can anyone share their opinions on manufacturers and/or models that are appropriate. An offline response may be appropriate. Sincerely, Derek Walton L F Research - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org David Heald dhe...@gmail.com - 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 emc-p...@ieee.org 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 emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org David Heald dhe...@gmail.com
