Professional Development Short Course On: Introduction to Electromagnetic Compatibility Instructor: Dr. William G. DuffATI Course Schedule: http://www.ATIcourses.com/schedule.htmATIs Space Based Radar: http://www.aticourses.com/introduction_emi.htm
Introduction to EMI / EMC Summary February 24-26, 2009 This three day course is designed for technicians, operators and engineers who need an understanding of Beltsville, Maryland Electromagnetic Interference (EMI)/Electromagnetic Compatibility (EMC) methodology and concepts. The $1490 (8:30am - 4:30pm) course provides a basic working knowledge of the "Register 3 or More & Receive $10000 each principles of EMC. Off The Course Tuition." The course will provide real world examples and case histories. Computer software will be used to simulate and demonstrate various concepts and help to bridge the gap between theory and the real world. The computer software will be made available to the attendees. One of the computer programs is used to design interconnecting equipments. This program demonstrates the impact of various EMI “EMI mitigation techniques" that are applied. Another computer program is used to design a shielded enclosure. The program considers the box material; seams and gaskets; cooling and viewing apertures; and various Course Outline "EMI mitigation techniques" that may be used for 1. Examples Of Communications System. A aperture protection. Discussion Of Case Histories Of Communications There are also hardware demonstrations of the System EMI, Definitions Of Systems, Both Military effect of various compromises on the shielding And Industrial, And Typical Modes Of System effectiveness of an enclosure. The compromises that are demonstrated are seam leakage, and a conductor Interactions Including Antennas, Transmitters And penetrating the enclosure. The hardware Receivers And Receiver Responses. demonstrations also include incorporating various "EMI 2. Quantification Of Communication System mitigation techniques" and illustrating their impact. EMI. A Discussion Of The Elements Of Interference, Including Antennas, Transmitters, Receivers And Instructor Propagation. Dr. William G. Duff (Bill) is the President of 3. Electronic Equipment And System EMI SEMTAS. Previously, he was the Chief Concepts. A Description Of Examples Of EMI Technology Officer of the Advanced Coupling Modes To Include Equipment Emissions Technology Group of SENTEL. Prior to And Susceptibilities. working for SENTEL, he worked for 4. Common-Mode Coupling. A Discussion Of Atlantic Research and taught courses Common-Mode Coupling Mechanisms Including on electromagnetic interference (EMI) and electromagnetic compatibility Field To Cable, Ground Impedance, Ground Loop (EMC). He is internationally recognized And Coupling Reduction Techniques. as a leader in the development of engineering 5. Differential-Mode Coupling. A Discussion technology for achieving EMC in communication and Of Differential-Mode Coupling Mechanisms electronic systems. He has 42 years of experience in Including Field To Cable, Cable To Cable And EMI/EMC analysis, design, test and problem solving for Coupling Reduction Techniques. a wide variety of communication and electronic systems. He has extensive experience in assessing 6. Other Coupling Mechanisms. A Discussion EMI at the equipment and/or the system level and Of Power Supplies And Victim Amplifiers. applying EMI suppression and control techniques to 7. The Importance Of Grounding For "fix" problems. Achieving EMC. A Discussion Of Grounding, Bill has written more than 40 technical papers and Including The Reasons (I.E., Safety, Lightning four books on EMC. He also regularly teaches Control, EMC, Etc.), Grounding Schemes (Single seminar courses on EMC. He is a past president of the Point, Multi-Point And Hybrid), Shield Grounding IEEE EMC Society. He served a number of terms as a member of the EMC Society Board of Directors and is And Bonding. currently Chairman of the EMC Society Fellow 8. The Importance Of Shielding. A Discussion Evaluation Committee and an Associate Editor for the Of Shielding Effectiveness, Including Shielding EMC Society Newsletter. He is a NARTE Certified EMC Considerations (Reflective And Absorptive). Engineer. 9. Shielding Design. A Description Of Shielding Compromises (I.E., Apertures, Gaskets, What You Will Learn Waveguide Beyond Cut-Off). • Examples of Communications Systems EMI. 10. EMI Diagnostics And Fixes. A Discussion • Quantification of Systems EMI. Of Techniques Used In EMI Diagnostics And Fixes. • Equipment and System EMI Concepts. 11. EMC Specifications, Standards And • Source and Victim Coupling Modes. Measurements. A Discussion Of The Genesis Of • Importance of Grounding. EMC Documentation Including A Historical • Shielding Designs. Summary, The Rationale, And A Review Of MIL- • EMI Diagnostics. Stds, FCC And CISPR Requirements. • EMC/EMI Specifications and Standards.52 – Vol. 96 Register online at www.ATIcourses.com or call ATI at 888.501.2100 or 410.956.8805
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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
ELECTROMAGNETIC ENVIRONMENT EFFECTS (E3) Performance degradation of receiver signal processing circuits Erroneous or inadvertent operation of electromechanical equipments, electronic circuits, components, ordnance, etc. Burnout or voltage breakdown of components, antennas, etc.
ELECTROMAGNETIC ENVIRONMENT EFFECTS (E3) CONTINUED Unintentional denotation or ignition of electroexplosive devices, flammable materials, etc. Personnel Injuries
ELEMENTS OF EMISOURCES VICTIM OF OF EMI COUPLING EMI
EXAMPLES OF NARROWBAND EMI UNITS Conducted Power Voltage Current W V A dBW dBV dBA dBm dBμV dBμA Radiated Power Density Field Strength Magnetic Field (H) Magnetic Flux Density (B) W/m2 V/m A/m Tesla (Weber/m2) dBW/m2 dBv/m dBA/m Picotesla (pT) dBm/m2 dBμV/m dBμA/m dBpT
EXAMPLES OF BROADBAND EMI UNITS Conducted Power Voltage Current dBm/kHz dBμV/MHz dBμA/MHz RadiatedPower Density Field Strength Magnetic Field (H) Magnetic Flux Density (B) dBm/m2/kHz dBμV/m/MHz dBμA/m/MHz dBpT/MHz
Filter Affects on a PulseVin V1 Tin Vin T1 F1 Tin V1 = F1TinVin T1 = 1/F1
Electric-Field Strength vs.Transmitter Distance and ERP*
EMI MITIGATION FOR OTHER SYSTEMSRadiated EMI Mitigation• Shielding• Circuit Design• Cable Selection and LayoutConducted EMI Mitagation• Grounding• Filters, Ferrites, Isolation Transformers, Optical Isolators, etc.
TWO-BOX EMI SEVERAL MILLION COMBINATIONS! MANY WITH AN INFINITE RANGE OF VARIABLES.
MANIFESTATIONSMultiple Sites • Battle Force - EME Site • Aircraft, Ship or Building System • Fire-Control Radar, Control System Subsystem • Equipment Racks, Consoles Equipment • R.F. Receiver, Medical Instrument Mother • Main Distribution to PCB Board PCB • Cards to Hold DIPS ComponentsComponent • DIPS, CHIPS, Relays
COUPLINGConducted power or signal cable couplingCommon-ground impedance common-mode couplingField-to-Cable or Cable-to-Field common-mode couplingField-to-cable or Cable-to-Field differential-mode couplingCable-to-Cable differential-mode couplingCase Radiation-Case Penetration
CONDUCTED EMI“EMI always start out at the culprit and ends up at the victim as a conducted signal regardless of what goes on between these two points!”
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?
PRINCIPAL RADIATION SOURCES ON PRINTED CIRCUIT BOARD Radiation from IC dips Logic families clock rates • Large single-layer board • PCB card cage with back plane • Multi-layer board Radiation from ribbon cables
MAGNETIC FIELDS FROM A TWISTED PAIR OF CONDUCTORS (TRANSPOSITION) Area 2 Area 1 I1 I2V ΔV2 ΔV1 RL I2 I1
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
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
PP47645A Some System EMC Fix Applications PP47645A
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