EMC

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Tutorial on electric, magnetic and electro-magnetic fields and possible technical disturbances hereby caused

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EMC

  1. 1. Everything you always should know about high frequency<br />Stefan Fassbinder<br />Deutsches Kupferinstitut<br />Am Bonneshof 5<br />D-40474 Düsseldorf<br />Tel.: +49 211 4796-323<br />Fax: +49 211 4796-310<br />sfassbinder@kupferinstitut.de<br />www.kupferinstitut.de<br />
  2. 2. The German Copper Institute, DKI, is the central information and advisory service dealing with all uses of copper and copper alloys. We offer our services to:<br /><ul><li>Commercial companies
  3. 3. The skilled trades
  4. 4. Industry
  5. 5. R & D institutes
  6. 6. Universities
  7. 7. Artists and craftsmen
  8. 8. Students
  9. 9. Private individuals</li></ul>We can be contacted by:<br /><ul><li> post
  10. 10. phone
  11. 11. fax
  12. 12. e-mail
  13. 13. internet
  14. 14. online database, or
  15. 15. personally</li></li></ul><li>Complementary elements:Inductances and capacitances<br />
  16. 16. What really is that,E = 1 V/m?<br />The fieldstrength bet-ween any twoelectrodesat a spacing of d = 1 m,between whicha voltage of U = 1 Vis applied<br />
  17. 17. What really is that,H = 1 A/m?<br />I = 1 A<br />A field line with a length of 1m around a conductor through which a 1A current is passing<br />At a distance ofthere is a field strength of 1A/m<br />
  18. 18. What really is a magnetic flux density of B = 1 T = 1 Vs/m² ?<br />Iron length: E. g. 300 mm mean,µR = 300<br />Corresponds to 600 mm iron altogether or2 mm air<br />Field strengthwithin the core:<br />within the gap:<br />within the entire field, whereas:<br /> Air gap: E. g. 1 mm, µR = 1<br />
  19. 19. Complementary elements: Inductances and capacitances<br />
  20. 20. I<br />I<br />IL<br />IC<br />U<br />U<br />UL<br />UC<br />Complementaryelements<br />Inductance:<br />Current leads voltage by 90°<br />or<br />voltage lags behind current by 90°, respectively<br />Capacitance:<br />Current leads voltage by 90°<br />or<br />voltage lags by 90° behind current, respectively<br />
  21. 21. Z<br />R<br />XC+ XL<br />XCRXL<br />Complementaryelements<br />Result:<br />180° Phase shift between voltages across or currents in L and C, respectively, so: Inductive und capacitive Reactances subtract linearly!Vectoral:<br />Linear:<br />
  22. 22. XCRXL<br />Let us clarify some terms1. Resonance<br />
  23. 23. i<br />Howtoimaginethis?<br />
  24. 24. i<br />i<br />i<br />i<br />i<br />i<br />Howtoimaginethis?<br />
  25. 25. i<br />i<br />i<br />i<br />i<br />i<br />Howtoimaginethis?<br />
  26. 26. i<br />i<br />i<br />i<br />i<br />i<br />Howtoimaginethis?<br />
  27. 27. Serial resonant filters (acceptorcircuits)<br />UR<br />R<br />U<br />let the resonance frequency f0 pass without any reactance<br />vectoral description<br />L<br />UL<br />UC<br />C<br />
  28. 28. Attention: From outside you don't seewhat's going on inside!<br />UR<br />R<br />U<br />L<br />UL<br />UC<br />Say:L and C do not limit the current!<br />C<br />I<br />
  29. 29. Parallel resonant filters (rejectioncircuits)<br />I≈0<br />U<br />block currents of the resonant frequency f0<br />(vectoral description)<br />C<br />L<br />R≈0<br />
  30. 30. Attention: From outside you don't seewhat's going on inside!<br />I≈0<br />U<br />There is practically no current flowing through the resonant circuit, but possibly a lot within the resonant circuit!<br />C<br />L<br />R≈0<br />
  31. 31. There are many LC pairs yielding the same resonant frequency, LF or HF…<br />Reactor reactance<br />Capacitor reactance<br />Serial impedance<br />Phase angle<br />
  32. 32. …but L by C defines the behaviourin the rest of the frequency range!<br />Reactor reactance<br />Capacitor reactance<br />Serial impedance<br />Phase angle<br />
  33. 33. …but L by C defines the behaviourin the rest of the frequency range!<br />Reactor reactance<br />Capacitor reactance<br />Serial impedance<br />Phase angle<br />
  34. 34. The total energy stored within the resonant circuit remains the same<br />
  35. 35. 2.Characteristicimpedance<br />is calculated from the specific line dimensions:<br />Longitundinal inductance L‘ and transversal capacitance C‘ per unit of length.<br />Model of an electric transmission line:<br />
  36. 36. Line with greatcharacteristic impedance:Line with low characteristic impedance:<br />
  37. 37. Line with small charac-teristic impedance<br />Speed of propagation: 299.792,5 km/s<br />
  38. 38. Line with great charac-teristic impedance<br />Speed of propagation: 299.792,5 km/s<br />
  39. 39. By the way, how fast does current really flow?<br />1 copper atom has 29 electrons. One of them is mobile.<br />1 mole of copper (63.546 g equalling 7.108 cm³) contains 6.02*1022 atoms (Avogadro's Constant).<br />1 g of copper thereby contains 9.47345*1021 electrons.<br />So per gram 3.26671*1020 of them are mobile, this is 3.654*1019 per cubic centimetre.<br />A current of 1 A means that at any point of the conductor 6.25*1018 electrons come flowing by (for each electron carries a charge of e = 1.9*10-19 As with it).<br />With 16 A flowing in a 1.5 mm² residential installation cable this yields 0.8 mm/s.<br />In case of short circuit it may be up to 50 mm/s!<br />
  40. 40. Vital for assessing im-pulse waves reflections, e. g. at the interfaces between overhead and underground lines<br />
  41. 41. Important in order to avoid reflections:<br />Terminating resistor, e. g. inside an antenna socket designed as a pass-through outlet but then used as a terminating outlet.<br />The amplitude of the terminating resistor has to equal the characteristic impedance, in this case e. g. 75 Ω:<br />
  42. 42. Only applicable in information technology, of course! Or…<br />Specific values of a 380 kV overhead line:<br />Values of a 380 kV underground cable:<br /> VPE<br /> Oil<br />
  43. 43. This would result in a »natural power« of…<br />Forheaven'ssake!<br />
  44. 44. 3. Limit frequencies,4. Bandwidth and hence5. the quality<br />of a reactor,<br />of a capacitor,<br />a resonant circuit<br />
  45. 45. 3. Limit frequencies f1 and f24. Bandwidth B<br />f2<br />f0<br />f1<br />B<br />Reactorreactance<br />Capacitorreactance<br />Serial impedance<br />Phase angle<br />
  46. 46. 3. Limit frequencies f1 and f24. Bandwidth B<br />f2<br />f0è<br />f1 è<br />B<br />Reactor reactance<br />Capacitor reactance<br />Serial impedance<br />Phase angle<br />
  47. 47. Rejectioncircuits<br />Reactor reactance<br />Capacitor reactance<br />Serialimpedance<br />Phase angle<br />
  48. 48. 5. Quality is an issue,described by thequality factor Q<br />What matters is the ratio of the reactive by the active share of the impedance, for active load means active power, and active power means<br /><ul><li>power loss
  49. 49. attenuation</li></li></ul><li>Between line and high frequency: Sound frequency<br />Which one is the right cable<br />to carry the sound to the speaker?<br />
  50. 50. 6.Interference<br />Adding two<br />voltages of<br />50 Hz and 51 Hz<br />and equal peak values<br />
  51. 51. Direct voltage; low frequency:<br />Electrical fields<br />Direct current; low frequency:<br />Magnetic fields<br />High frequency (above ≈30 kHz):Electro-magnetic fields<br />
  52. 52. Howtoimaginethis?<br />
  53. 53. Howtoimaginethis?<br />
  54. 54. Howtoimaginethis?<br />
  55. 55. Howtoimaginethis?<br />
  56. 56. Howtoimaginethis?<br />
  57. 57. Howtoimaginethis?<br />
  58. 58. Howtoimaginethis?<br />
  59. 59. Howtoimaginethis?<br />
  60. 60. Howtoimaginethis?<br />
  61. 61. Howtoimaginethis?<br />
  62. 62. Howtoimaginethis?<br />
  63. 63. This is how to imagine this!<br />These fields radiate andmay beused for transmittinginformation<br />over shortand longdistances<br />
  64. 64. …or they may disturb said transmissions!<br />Well, if you don't apply any filters…<br />
  65. 65. Thisbatteryoperatedthermometerlocated ≈30 cm off a fluorescentlampdiditsjobfairly well until<br />displayedtheroomtemperaturefairly well until…<br />…thelighthadbeenswitched a fewtimes – thenthedisplaysuddenlyturnedkryptic!<br />
  66. 66. There are three types of coupling mechanisms<br />Galvanic:<br />Electrically conductive connection<br />ê<br />Electrons flow »personally« from source to sink.<br />Sort of disturbance:PEN conductor, TN-C system<br />Inductive:<br />current<br />ê<br />magnetic field<br />ê<br />induction<br />Capacitive:<br />voltage<br />ê<br />electrical field<br />ê<br />influence<br />NFNF<br />HF<br />Electro-magnetic fields,radiation / susceptibility (HF)<br />
  67. 67. 1.Galvaniccoupling<br />What does this gentleman want to show you here?<br />The leading example of galvanic coupling:<br />Multiple connections between N and PE, i. e. between energy and information technique (operational earth)<br />
  68. 68. U<br />2. Inductive coupling<br />With operating currents: di/dt≈ 50 A/ms<br />Signal level Cat. 3 data lines: 1 V<br />Signal level Cat. 5 data lines: 500 mV<br />Signal level 10Gbit/s beginning: 130 mV<br />Signal level 10Gbit/s end: 600 µV!<br />With short-circuit currents: di/dt≈ 1 kA/ms<br />With switching transients: di/dt≈ 10 kA/ms<br />In inverterdrives: di/dt≈ 50 kA/ms<br />With lightning currents: di/dt≈ 50 kA/µs!<br />l<br />d<br />~<br />I<br />
  69. 69. 3.Capacitivecoupling<br />I<br />U<br />I<br />
  70. 70. 3.Capacitivecoupling<br />I<br />U<br />
  71. 71. 3.Capacitivecoupling<br />I<br />U<br />I<br />
  72. 72. There are three of all evils: Coupling mechanisms in practice<br /><br />Inductive coupling:<br />N against PE<br /><br />Capacitive coupling:<br />MV against PE?<br />Galvaniccoupling:<br />»Second CEP«<br />Only here it shall be<br />è<br /><br />
  73. 73. Therefore:Mind the coupling mechanisms!<br />Galvanic coupling:Once and only once (CEP)<br /><ul><li>Capacitive coupling:A very thin electricallyconductive layer suffices – if earthed!
  74. 74. Inductive coupling:Thick magneticallyconductive layers required!</li></li></ul><li>And:Mindthereferencestocableducts in thestandards!<br />Z. B. IEC 60364-4-44<br />(DIN EN 50174-2 / VDE 0800-174-2)<br />
  75. 75. And:Note thereferencesre-gardingthecablepositioning!<br />Z. B. IEC 60364-4-44<br />(DIN EN 50174-2 / VDE 0800-174-2)<br />
  76. 76. Do not confuse:<br />Analogueand digital cables<br />Analogue cables have a screen.<br />Digital cables have some-thing that looks like a screen.<br />
  77. 77. How to deal with coupling mechanisms?<br />By just dodgingthem!<br />Differential mode:<br />Savestrouble<br />Common mode:<br />Savescopper<br />
  78. 78. Spicing things up with a pinch of HF: A piece of cake when using an electronic transformer<br />
  79. 79. Any sort of radiation:Decorative HF reactors<br />
  80. 80. The European Union<br />has been providing a total of three million Euros over athree year period to enable experts from across Europeto co-operate in the development of the definitive internet site covering all aspects of power quality!<br />To follow the latest developments visit<br />www.leonardo-energy.org<br />and take a look at the growing body of information that has been made available by the Leonardo Power Quality and the Leonardo Energy Initiatives.<br />Our aim is to develop and disseminate teaching materials in 13 languages dealing with the detection, mitigation and management of EMC problems.<br />Target groups include electrical technicians, engineers, those in the skilled trades, building system engineers, architects, planners as well as apprentice technicians and students and their teachers.<br />At present the Power Quality Initiative has 165 members from commercial companies, institutions, universities and trade associations.<br />We openly encourage other industrial and academic partners to participate in this project and welcome contributions at any time.<br />Just log on!<br />Awardedthreeprojects out of about4000 in December 2004 – one of thembeingtheLeonardo Power Quality Initiative<br />
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