Practical EMC and EMI Control for Engineers and Technicians
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This workshop focuses on the issues of interest to you if you are working in design, operation or maintenance of analog or digital systems involving sensors, data acquisition, process control, cables, signal processing, programmable logic controllers, power distribution, high speed logic etc. The circuit board layout section concentrates on design and layout of circuits and components on a printed circuit board. The overall focus is on useful design and systems issues; not about regulations and standards. The idea is that you will take this material back with you to your work and apply the key principles immediately to your design and troubleshooting challenges. WHO SHOULD ATTEND? Electrical and electronic engineers and technicians Engineers and technicians involved in the design and manufacture of electrical and electronic equipment which produce electromagnetic disturbances and may be susceptible to electromagnetic interference Engineers and technicians involved with the maintenance and service of electrical and electronic equipment Instrumentation and control engineers and technicians Those that need to ensure that goods conform to the required standards Those involved in the marketing and sale of goods that need to comply with the required standards MORE INFORMATION: http://www.idc-online.com/content/practical-emc-and-emi-control-engineers-and-technicians-2
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Practical EMC and EMI Control for Engineers and Technicians
- 1. Technology www.idc-online.com/slideshare Training that Works ID C Practical EMC and EMI Control for Engineers and Technicians
- 2. Technology www.idc-online.com/slideshare Training that Works ID C Oops ... Falklands war: HMS Sheffield turned off the missile warning radar - interfered with the satellite communication system. Sunk by a missile
- 3. Technology www.idc-online.com/slideshare Training that Works ID C … oops! Feb ’99: DC 10 approaching JFK. Banked left, almost caused a crash. CD player in 1st-class suspected.
- 4. Technology www.idc-online.com/slideshare Training that Works ID C Structural Engineering “ … the art of modelling materials we do not understand, into shapes we cannot precisely analyse, to withstand forces we cannot properly assess, in such a way that the public at large has no reason to suspect the extent of our ignorance”. (past Chairman of the Scottish branch of the Institute of Structural Engineers) Sound Familiar?
- 5. Technology www.idc-online.com/slideshare Training that Works ID C Vocabulary: EMC vs EMI EMI - Electromagnetic Interference » This is the PROBLEM EMC - Electromagnetic Compatibility » This is the SOLUTION
- 6. Technology www.idc-online.com/slideshare Training that Works ID C
- 7. Technology www.idc-online.com/slideshare Training that Works ID C Intermittent EMI Sources
- 8. Technology www.idc-online.com/slideshare Training that Works ID C The Need for Standards Standards are needed to control/limit interference from electronic devices Standards are also needed to make electronic devices less susceptible to interference Various countries implemented their own standards Any manufacturer wanting to market goods into that country, has to comply with the standards
- 9. Technology www.idc-online.com/slideshare Training that Works ID C EMC - the issues Controlled outptuts Control/signal inputs Disturbing or emitted surges Radiated or conducted RF, emitted harmonics Radiated EMD Susceptibility to EMD Radiation from outputs Susceptibility to EMD Earth coupling/ bonding problems PQ phenomena
- 10. Technology www.idc-online.com/slideshare Training that Works ID C Electromagnetic disturbances (any electromagnetic phenomenon which may degrade performance, without regard to frequency or coupling method) Supply voltage » interruptions » dips » surges » waveform distortion » fluctuations slow rms variations rapid rms variations (flicker) » Voltage unbalance » Frequency variations » DC in AC networks » Power-line carrier signaling
- 11. Technology www.idc-online.com/slideshare Training that Works ID C Electromagnetic Disturbances Transient overvoltages » supply lines » signal lines » control lines lightning switching ESD (electrostatic discharge)
- 12. Technology www.idc-online.com/slideshare Training that Works ID C Electromagnetic Disturbances Radio frequency fields » pulsed (radar) » modulated » continuous » coupled directly to equipment » coupled into connected cables LF magnetic or electric fields NEMP (Nuclear Electromagnetic Pulse)
- 13. EMC Testing Categories Radiated Susceptibility (RS) POWER Conducted Susceptibility (CS) POWER Technology www.idc-online.com/slideshare Training that Works ID C Radiated Emissions (RE) POWER SIGNALS Conducted Emissions (CE) POWER SIGNALS NOISE CURRENT Radiated Conducted Emissions Susceptibility / Immunity SIGNALS DISTURBANCE SIGNAL INJECTED SIGNALS
- 14. Technology www.idc-online.com/slideshare Training that Works ID C Electromagnetic susceptibility The inability of a device, equipment or system to perform without degradation in the presence of an electromagnetic disturbance OR Immunity (to electromagnetic disturbances) The ability of a device, equipment or system to perform without degradation in the presence of an electromagnetic disturbance
- 15. Technology www.idc-online.com/slideshare Training that Works ID C The compatibility gap Valves Transistors ICs Switchgear Radio/Radar/ TV Industrial Cellphones electronics Decreasing immunity Increasing emission EMC Directive
- 16. Emission limit Technology www.idc-online.com/slideshare Training that Works ID C Emission, immunity compatibility Immunity level Immunity limit Emission level Compatibility level Immunity margin Emission margin Compatibility margin Design margin Design margin Independent variable
- 17. Technology www.idc-online.com/slideshare Training that Works ID C Considerations Consequences of EMI » catastrophic death; major injuries; downstream consequences » critical minor injuries; extensive damage » major minor permanent damage » minor temporary performance loss » inconsequential loss of performance within tolerance; no human intervention needed
- 18. Technology www.idc-online.com/slideshare Training that Works ID C Test result classification Normal performance within specified limits temporary degradation or loss of function; self-recoverable temporary degradation or loss of function; requires human intervention or system reset degradation or loss of function due to physical damage; software or data corruption
- 19. Special Requirements • Self Imposed • Improved Integration / Functionality • Basic EMC design rules • Minimum Specification / Standards Technology www.idc-online.com/slideshare Training that Works ID C Levels of Compliance Self Compatibility • Harsh Environment • Exceeds Standards • Environment Dominates • Functional • Just making it work • No EMC design rules Contractual Compliance • Electrical EM Environment (E3) • To Specification • EMC Engineering • Mandatory Testing Minimum Engineering / In-house standard
- 20. Areas of EMC Engineering Application PCB’s » Most subtle, but very cost effective Circuits and Filters » Added circuitry to contain EMI » Adds cost but a necessity for good EMC design Screening » Enclosures and cables » Brute force - least cost effective Grounding » Applicable to all three areas above Technology www.idc-online.com/slideshare Training that Works ID C
- 21. Technology www.idc-online.com/slideshare Training that Works ID C DO YOU WANT TO KNOW MORE? If you are interested in further training or information, please visit: http://idc-online.com/slideshare
Editor's Notes
- Electronic equipment is both capable of emitting unintended signals, and of being affected by spurious radiation from other electronic equipment. Putting electronics products together without their affecting each other, is the challenge. Meeting the challenge is a combination of legislation, engineering and consideration for the needs of others.
- An engineering company installed a CAD system to speed up design time. However, the system crashed so often that they were falling even further behind. Numerous calls to the suppliers failed to solve the problem which everyone assumed was software-related. Investigation showed eventually that it was caused by a large drawing reproduction machine which injected transients onto the mains supply.
- Much of the bad press surrounding CD players and aricraft, seems to have originated with a Lufthansa flight where a system operating at 112 MHz had problems which were traced to a CD player with a clock rate of 28 MHz (4 x 28 = 112). A paper mill in Stanger (South Africa) was experiencing trips on its 1 MVA variable speed drive system. A voltage dip of 20%, lasting for more than 40 ms was enough to trip the system and would result in several hours of downtime while the paper web was re-threaded and the system started up again. Installation of a SMES (Superconducting Magnetic Energy Storage System) has meant that there have been no further system trips since 1997. In an aerospace factory, a plastic welder was being operated quite legally. Nearby is a mattress factory. Although the two are tens of metres away from each other, the welder caused a mattress to burst into flames.
- Any electronic device will emit radiation in the form of radiated RF electromagnetic disturbances from the device itself radiated RF electromagnetic disturbances from its input and output connections conducted EMD via its I/O connections or power lines and be susceptible to EMD from stray radiations from other electronic equipment directly stray radiations from the I/O of other electronic equipment directly conducted disturbances via mains lines or I/O, or mains voltage variations or waveshape
- All of these are covered in detail in later modules
- All of these are covered in detail in later modules
- All of these are covered in detail in later modules
- All electronic devices are susceptible to electromagnetic disturbances - if they were not, there would be no EMC issues. However, none are totally immune, so the problem exists
- As electronic devices run faster and faster off reducing supply voltages, they become increasingly susceptible to the prevailing electromagnetic disturbances. Simultaneously, the number of installed computers, Hi-Fi’s, games, motor drives and mobile phones means that the atmospheric electromagnetic pollution is increasing at a rapid rate. Only legislation to limit the effects of interaction can solve the problem.
- Obviously then, devices need to co-exist without treading on each others’ toes - they need to be ‘compatible’ with each other, hence the term. It is important that these terms are understood.
- If EMI causes malfunction of a safety-critical item of machinery erratic operation of moving equipment a safety device to ignore a signal an operation to stop for no apparent reason not carry out its intended function, but not cause any havoc as a result the malfunction will fall into the above classifications.
- For an item of equipment to pass a test, the test result must be determined beforehand. An important part of achieving compliance with any regulation, is that the specification details what will happen under EMI conditions. For some equipment, the effects of interference (eg slight noise on a telephone) are not terribly critical.
- There are different levels of EMC engineering. The above compliance ‘structure’ shows different levels at which designers and companies operate. The above is useful to appreciate the change in engineering strategy when say a company was just struggleling to make things works, but must now comply with specifications.
- This course aims to equip the student with tools to design for and reduce EMI. Three main area’s of application will be dealt with: PCB’s, Circuits/Filters and Screening. Proper grounding is underlying to all of the above areas and is also dealt with.