Introduction to EMI/EMC PDF

1. Introduction to EMI/EMC 2  EMI in the Sky On a flight from New York City’s La Guardia airport to Chicago’s O’Hare airport, the captain observed an interference on the navigational equipment during take-off. They found a passenger using...

1. Introduction to EMI/EMC 2  EMI in the Sky On a flight from New York City’s La Guardia airport to Chicago’s O’Hare airport, the captain observed an interference on the navigational equipment during take-off. They found a passenger using a laptop computer, and asked him to turn it off. Sometime later, the same navigational problems recurred; the same man had again turned on his laptop. As the plane was descending, the VORs again had problems. Once more the passenger had turned his computer on. He refused repeatedly to turn it off. The passenger was arrested for disorderly conduct. EMI = Electromagnetic Interference [Source: IEEE Spectrum, Feb. 1994, p.21] 3 4  ESD on a PC A Workstation Support person was attending to a call regarding a PC which was continually freezing up. … air- conditioner … very dry atmosphere. The staff noticed a lot of static charge on his clothes and the client’s. The client did have a static discharge pad under her keyboard but had not been touching it prior to using the keyboard. Support person instructed her to do so and … no more freezing problem …! ESD = Electrostatic Discharge 5  ESD on a Motor Vehicle A “Vehicle Safety Recall” was issued by a well-known motor vehicle manufacturer for six vehicle models manufactured between 1995 and 1996. “There exists a remote possibility that the driver air bag may inadvertently deploy in certain atmospheric conditions (high static electricity charges). This may only occur when the driver is entering or exiting the vehicle and touches the centre (air bag area) of the steering wheel.” … The recall service will be carried out free of charge… [Source: The Australian, p. 7, Monday February 16, 1998] 6 7 [Source: Electronics Australia] 8  What is EMC? EMC = Electromagnetic compatibility Definition [IEC 61000-1-1] The ability of a device, unit of equipment, or system to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbances to anything in that environment. 9  European EMC Directive 89/336/EEC,... 92/31/EEC,... 2004/108/EC* The electromagnetic disturbance generated by an apparatus does not exceed a level allowing the radio and telecommunications equipment and other apparatus to operate as intended. The apparatus has an adequate level of intrinsic immunity to the electromagnetic disturbance to enable it to operate as intended. *EMC Directive 2004/108/EC was published in the Office Journal (OJ) on 31 December 2004. 89/336/EEC to be repealed as from 20 July 2007. 10  Two Aspects to Consider Emission the ability to operate without interfering with others Immunity the ability to operate within a specified electromagnetic environment 11  What is EMC? Electromagnetic Compatibility (EMC) Immunity Emission (Susceptibility) Conducted Radiated Conducted Radiated Emission Emission Immunity Immunity 12  What is EMC? (cont’d) EMISSIONS Conducted Emissions (CE) Radiated Emissions (RE) SIGNALS CONDUCTED POWER RAD IAT E D POWER SIGNALS Conducted Susceptibility (CS) Radiated Susceptibility (RS) SIGNALS POWER SIGNALS POWER SUSCEPTIBILITY 13 “Ingredients” for Electromagnetic Interference (EMI) Disturbance Coupling Path Susceptible Source Victim/Receptor 14 Intentional and Unintentional Emitters and Receptors Intentional Emitters: Intentional Receptors: Broadcast transmitters communications Radio/TV receivers Mobile phones Mobile phones Wireless LAN Wireless LAN Remote-controlled transmitter Remote-controlled receiver Unintentional Emitters: Unintentional Receptors: Digital circuits/oscillators interference Telephone lines Switching circuits Audio-visual systems Auto ignition Analog circuits Lightning/ESD Digital circuits 15  Lightning an example of a naturally occurring noise source Brisbane 19 May 2005 [Image Source: Wikipedia, http://en.wikipedia.org/wiki/Lightning] 16  Lightning: Ground Voltage Gradient Cloud Base from 1500 To 6500 ft AGL From 300k to 7.5 Million V Ground Gradient of 30 kA to 1000 to 3000 V/ft 50 kA 17  100 URBAN 10 SUBURBAN Field Strength (mV/m) 1.0 DAYTIME 0.1 ATMOSPHERIC NOISE NIGHT TIME 0.01 10 100 1000 10,000 Frequency (MHz) 18 Coupling Paths: Conducted and Radiated Radiated, chassis To mains Source External cable Equipment Peripheral Conducted, Through common Mains Impedance Radiated, chassis to chassis Radiated, Conducted, cable to cable Through common earth Impedance Victim External Input Equipment External Mains Interference 19  Intersystem and Intrasystem EMC Intersystem EMC – Source and victim are in two different pieces of an equipment – A victim may also be a source – Need to comply with the EMC regulations Radio & TV Lightning Broadcast Conducted Noise AC Power Circuit Electric Motors Mobile Radio 20 Intersystem and Intrasystem EMC (cont’d) Intrasystem EMC – Source and victim are in the same piece of an equipment – Usually an in-house problem 21  EMI Mitigation Methods Separation in SPACE Separation in TIME Separation in FREQUENCY Application of the Design Techniques to: – minimise source emissions – minimise path couplings – minimise victim susceptibility 22  Compatibility Sources with Receptors with controlled adequate emissions immunity 23  Levels of Compliance harsh environment Special/Contractual security, … etc Requirements military standards + … sales, trade Regulatory legal obligation Requirements commercial standards functionality In-house reliability Requirements self-imposed design rules 24  Why Do We Need EMC Regulations? Safeguard the consumers Protect the environment Market forces International trade – import and export (free trade) Prevent dumping Legal responsibility 25  EMC Regulations Europe ("International") – EMC Directive (CE label) United States – Federal Communications Commission (FCC) Rules FC C Australia/New Zealand – Australian EMC Framework (C-tick label) Other nations – implementing… Most EMC regulations (except USA) are based on the established international EMC standards which prescribe the test methods and limits. 26 Example of an EMC Compliance Labelling of a Product EUROPE Emission Immunity CANADA AUSTRALIA & NEW ZEALAND [Source: Keysight Technologies, E4980A brochure and data sheet] 27 International (CE) EMC Emission Standards CISPR 11 (IEC 61000-3-11): ISM equipment CISPR 12 (IEC 61000-3-12): Spark ignition engines CISPR 13 (IEC 61000-3-13): TV receivers and audio equipment CISPR 14 (IEC 61000-3-14): Electrical motor operated and thermal appliances, electric tools and similar apparatus CISPR 15 (IEC 61000-3-15): Electrical lighting and similar equipment CISPR 16 (IEC 61000-3-16): CISPR measurement methods and apparatus CISPR 19 (IEC 61000-3-19): Microwave ovens CISPR 22 (IEC 61000-3-22): Information technology 28  Class A and Class B Devices in EMC Emission Standards Class A Nondomestic establishment Class B Domestic establishments Other establishments using the LV supply connected to the domestic establishments Warning notice WARNING for Class A products: This is a Class A product. In a domestic environment this product may cause radio interference in which case the user may be required to take adequate measures. 29  IEC Immunity Standards IEC 61000-4-2 Electrostatic discharge (ESD) IEC 61000-4-3 Radiated EM Field IEC 61000-4-4 Fast transient/burst IEC 61000-4-5 Surge IEC 61000-4-6 Conducted disturbance IEC 61000-4-11 Supply dips and variations These are basic standards. They are referred to by generic and product standards. 30  EMC Terms and Acronyms EMC = Electromagnetic compatibility EMI = Electromagnetic interference EM Disturbance = “RF noise” EM Environment = “Where the RF noise exists” Immunity = Ability to reject EM disturbances Susceptibility = Tendency to be interfered by EM disturbances The following terms are the safety limits for a human (not EMC): – EMR = Electromagnetic radiation (RF emissions) – EMF = Electromagnetic field (AC mains E and H fields) 31  References T. Williams, “EMC for product designers”, 2007, Butterworth- Heinemann (5th edition, 2016 is also available). H. W. Ott, “Noise reduction techniques in electronic systems”, 1988, John-Wiley & Sons. The International Electrotechnical Commission homepage (http://www.iec.ch/). Publication Office of the Official Journal of European Union (http://publications.europa.eu/about_us/index_en.htm). Federal Communication Commission homepage (http://www.fcc.gov/aboutus.html). ANSI Accredited Standards Committee C63-EMC (http://www.c63.org/). C.R. Paul, “Introduction to electromagnetic compatibility”, Wiley Interscience, 1992. (2nd edition 2006 available) 32