ATI's Practical EMI Fixes Technical Training Course Sampler
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ATI's Practical EMI Fixes Technical Training Course Sampler

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ATI's Practical EMI Fixes Technical Training Course Sampler ATI's Practical EMI Fixes Technical Training Course Sampler Presentation Transcript

  • Professional Development Short Course On: Practical EMI Fixes Instructor: Dr. William G. DuffATI Course Schedule: http://www.ATIcourses.com/schedule.htmATIs Practical EMI Fixes: http://www.aticourses.com/practical_emi_fixes.htm 349 Berkshire Drive • Riva, Maryland 21140 888-501-2100 • 410-956-8805 Website: www.ATIcourses.com • Email: ATI@ATIcourses.com
  • www.ATIcourses.comBoost Your Skills 349 Berkshire Drive Riva, Maryland 21140with On-Site Courses Telephone 1-888-501-2100 / (410) 965-8805Tailored to Your Needs Fax (410) 956-5785 Email: ATI@ATIcourses.comThe Applied Technology Institute specializes in training programs for technical professionals. Our courses keep youcurrent in the state-of-the-art technology that is essential to keep your company on the cutting edge in today’s highlycompetitive marketplace. Since 1984, ATI has earned the trust of training departments nationwide, and has presentedon-site training at the major Navy, Air Force and NASA centers, and for a large number of contractors. Our trainingincreases effectiveness and productivity. Learn from the proven best.For a Free On-Site Quote Visit Us At: http://www.ATIcourses.com/free_onsite_quote.aspFor Our Current Public Course Schedule Go To: http://www.ATIcourses.com/schedule.htm
  • ELEMENTS OF EMISOURCES VICTIM OF OF EMI COUPLING EMI
  • EMI CULPRIT AND VICTIM EMI CULPRIT Source VICTIMSignal SignalSource Receiver COUPLING PATH
  • CONDUCTED OR RADIATED COUPLING SOURCE COUPLING VICTIM
  • Historical EMI/E3-Related Incidents Operation Restore Democracy (Haiti-1995) • Air wings of USS America & USS Eisenhower replaced with men & helicopters of 10th Pershing II Nuclear Missile (Germany) Infantry Div. and 75th Ranger Regiment. • Missile motor exploded during routine • Army aircraft not designed or tested for carrier maintenance operation, carriers required to turn off almost all • Electrostatic discharge identified as the communications and radar surveillance systems. cause • 3 dead USS Forrestal (Vietnam -1969) • ZUNI rocket inadvertently launched by a ship radar • 134 dead • 27 aircraft destroyed • $72M damage to ship ($335M in 2000 dollars) • Largest Naval loss of life since WW II Blackhawk Helicopter (Germany and USA - 1987)• Several potentially fatal incidents and a fatal crash HMS Sheffield (Falkland Islands -1982)• Suspected cause was interference from high Courtesy of Jose Reza • Hit by undetected EXOCET missile power radio transmitters • EMI caused degradation of surveillance• Entire fleet grounded for 3 months during radar investigation • 21 dead,• Extensive test and retrofit program necessary • Ship sank 4 days later
  • Shielding May Have Avoided Some of These Problems
  • Proper Grounding May HaveAvoided Some of These Problems
  • CONCEPTUAL ILLUSTRATION OF CONDUCTED AND RADIATEDEMISSIONS AND SUSCEPTIBILITY
  • NARROWBAND AND BROADBAND EMISSIONS
  • Filter Affects on a PulseVin V1 Tin Vin T1 F1 Tin V1 = F1TinVin T1 = 1/F1
  • UWB PRF > IFBWAi Ao Time Domain t t RF Input Output ReceiverA’i passband A’o f f f Frequency Domain
  • UWB PRF< IFBWAi Ao Time Domain t t RF Input Output ReceiverA’i passband A’o f f f Frequency Domain
  • THREE-DIMENSIONAL GEOMETRYILLUSTRATING GAIN OF ANTENNA
  • RECEIVER SUSCEPTIBILITY CHARACTERISTICS
  • RECEIVER SPURIOUS RESPONSES 50 MHz 60 MHz RF I.F. 10 MHz Mixer 100 MHz 120 MHz L.O. 210 MHz 110 MHz 230 MHz 220 MHz fSR = pfLO  fIF 320 MHz 340 MHz 330 MHz q
  • RECEIVER INTERMODULATION100 MHz101 MHz RF AMP R.F. Amplifier 100 MHz102 MHz fIM = mf1  nf2 m = 2; n = 1 (-) m = 3; n = 2 (-) m = 4; n = 3 (-)
  • INTERSYSTEM EMC DESIGN AND EMI CONTROL Communication-System Interference Design and Control Frequency Time Location DirectionManagement Management Management Management
  • Illustration of Common Mode Currents CMC 1 Power Source Load CMC 2 CMCIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII Metallic Structure Figure 4. Illustration of Common Mode Currents
  • Illustration of Differential Mode Currents DCM1 Power Source Load DCM2 Figure 3. Illustration of Differential Mode Currents
  • Illustration of Common and Differential Mode Currents CMC 1 DMC 1 Power Source Load CMC 2 DMC 2 CMC IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII Metallic Structure Figure 5. Illustration of Common and Differential Mode Currents Illustration of Common and Differential Mode Currents Illustration of Common and Differential Mode Currents
  • Common Mode Currents Resulting From Distributed Capacitance to Ground CMC 21 Power Source Load CMC 21 CMC1IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII Metallic Structure Figure 6. Common Mode Currents Resulting From Distributed Capacitance to Ground
  • Common Ground Impedance Common Mode EMI CMC Power Source Load CMC EMI EMIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII Metallic Structure Figure 10. Common Ground Impedence Common Mode EMI
  • Controlling Conducted EMI Source Victim Power Supplies Analog Equipment Motors Conducted Digital Equipment Inductive Loads EMI Video Display High Level Analog Recorders Digital Signals Instruments Transmitters Sensors EM Environment Control Systems Receivers Applicable EMI Control Techniques Differential Mode Common Mode (Ground Loop)Power Signal Power SignalFilter Filters Filters FilterFerrites Ferrites Ferrites FerriteIsolation Transformers Isolation Transformers Isolation Transformers Isolation TransformersTranslent Suppressors Translent Suppressors Balanced Systems Balanced Circuit Float Float Inductor in Ground Inductor in Ground Optical Isolator
  • WHAT IS GROUND ? SIGNAL RETURN? CHASSIS REFERENCE? SAFETY WIRE REFERENCE? EARTH REFERENCE?
  • ELECTROMAGNETIC SHIELDING
  • SHIELDING APPLIES TO ALL LEVELS Components  Systems Circuits  Cables Functional Stages  Platforms Equipments  Buildings
  • CABLES, CIRCUITS AND COMPONENTS ACT AS ANTENNAS
  • REPRESENTATION OF SHIELDING PHENOMENA FOR PLANE WAVES Ey Inside of Enclosure Hz Incident WaveA Ey Transmitted Wave Ey B H Ey Attenuated Hz Incident Hz Ey Hz Reflected Wave Wave Internal Reflecting Outside World Metal Wave Barrier
  • REFLECTION LOSS ( K  1) 2 ZW R dB  20 log 10 ,K  VSWR 4K Zb  Zw   20 log 10   , K  10  4 Zb Where : E Z w  wave impedance  H jω μ jω μ Z b  barrier impedance   σ  jω ε σfor ω ε   σ
  • REFLECTION LOSS (RdB) OF PLANE WAVES VS FREQUENCY 3kHz 30kHz 300kHz 3MHz 30MHz 300MHz 200 200 150 150 Copper 100 100 Iron* 50 Hypernick* 50 0 1kHz 10kHz 100kHz 1MHz 10MHz 100MHz 0 Radio Frequency Valid for thickness > 3   = Skin Depth * Permeability assumed constant with frequency
  • ABSORPTION LOSS, A Current Density 0.066 δ mm f MHz μ r σ r  t AdB  8.68 t / δ  131 t f MHz μ r σ r where t  thickness in mm f MHz  frequency in MHz μ r  permeabili ty relative to copper σ r  conductivi ty relative to copper
  • ABSORPTION LOSS VS FREQUENCY
  • TOTAL SHIELDING EFFECTIVENESS
  • PRINCIPAL BOX SHIELDING COMPROMISES Holes or Slots Screw Spacing Cover Plate for Convection Cooling = Slot Radiation for Access Status Indicator Lamp Forced Air Cooling Panel Meter Potentiometer Connectors Fuse Switch
  • SLOT AND APERTURE LEAKAGE L t h  t << h Shield MaterialSE (dB) 20 V. P dB . /d ec . •  Log Frequency • / 2
  • Shielded Enclosures Provide metal-to-metal contact at seams Use RF gasketing on access panels Use screws with lockwashers Use perforated grids or slots for opening
  • PP EMI-Fix Matrix - Fixes vs. Coupling Paths, Part 1 PP
  • PP EMI-Fix Matrix - Fixes vs. Coupling Paths, Part 2 PP