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Electromagnetic Interference Phenomena Picture or Drawing 20.7 x 8.6 cm Frits J.K. Buesink, Senior Researcher EMC [email protected] Funded by the European Union on the basis of Decision No 912/2009/EC, and identified in the European Metrology Research Program (EMRP) as Joint Research Project (JRP) IND60 EMC (2013-2016). Additional funding was received from the EMRP participating countries. UNIVERSITY OF TWENTE. in cooperation with TELECOMMUNICATION ENGINEERING. Two Aspects of Achieving EMC A. Engineering Compatible Equipment B. Qualifying Equipment for EMC A B “White Box” approach “Black Box” approach Partner in the Design Team Independent Incorporate EMC in the Design “GO” or “NO-GO” Get information from the EM-Network Standardized Approach Formulate Design Rules Find Problems and Fix them Large Stationary Installations in Industry EMRP IND60: Improved EMC methods (to qualify) In Industrial Environments in cooperation with Interference mechanisms in installations 2 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 1 The necessary elements for an interference situation EMI, ElectroMagnetic Interference model: source – victim and coupling path Source coupling path Victim Susceptibility (Immunity) Emission Coupling path: always electrical interconnections this can be demonstrated Effects appear using: a noise generator at any scale a radio receiver (relative wavelength) and sometocables Very large…. to tiny. in cooperation with Interference mechanisms in installations 3 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Essential Requirements: No Emission, No Susceptibility the question as to “how much” is answered by EMC Standards Noise level noisevoltage (LF) noisefields (HF) non-susceptibility (immunity) Generic standards immunity industrial EN-IEC 61000-6-2 immunity residential EN-IEC 61000-6-1 industrial EMC margin emission industrial EN-IEC 61000-6-4 emission residential EN-IEC 61000-6-3 residential emission For Europe: Source: C.J. Post Lambda Engineering B.V. EMC on Tour 2011 in cooperation with frequency Interference mechanisms in installations 4 UNIVERSITY OF TWENTE. 4 TELECOMMUNICATION ENGINEERING. 2 EMC “standard violation”: EMI = EM Interference if either emissions are too high or the immunity level is too low Noise Level noise voltages (LF) noise fields (HF) susceptibility immunity level (by standard) emission limit (by standard) emission Source: C.J. Post Lambda Engineering B.V. EMC on Tour 2011 in cooperation with frequency Interference mechanisms in installations 5 UNIVERSITY OF TWENTE. 5 TELECOMMUNICATION ENGINEERING. Common-mode currents dominate the EMC arena currents, generated by cables from “desired currents” into CM or ground-loop Source Load Idm “Differential-mode” current Icm “Common-mode” current “Ground” Icm(2) “Common-mode” current (2) System at the neighbours Idm Source in cooperation with Interference mechanisms in installations 6 Load UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 3 Induction in a Single Wire current in a conductor is only possible when a magnetic field exists 1. Waveform for fast edge A B 50 signal integrity = no distortion on the signal line A B coax cable single wire in cooperation with Interference mechanisms in installations 7 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Induction in a Single Wire current in a conductor is only possible when magnetic field exists 1a. Waveform for fast edge @ reduced loop area B 50 A Reduce loop area: less time and energy needed to build H-field A B coax cable single wire in cooperation with Interference mechanisms in installations 8 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 4 Induction in a Single Wire current in a conductor is only possible when magnetic field exists A B 50 2. Waveform for slow edge A B coax cable single wire in cooperation with Interference mechanisms in installations 9 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Cables are used to keep Signal and Return together field of the return conductor is identical but opposite (if geometry is identical) H = Magnetic Field [A/m] in cooperation with Interference mechanisms in installations -H 10 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 5 Current carrying conductor always exhibits H-field minimize fields by locating the return conductor concentric in cooperation with Interference mechanisms in installations 11 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Properties of cables: Transfer Impedance ZT cable may produce or pick up common mode currents 1. Coupling into external noise ZT cable length D Inoise U noise Inoise D [Ohm per meter] external noise source Unoise Idesired 2. Generation of noise in other conductors (e.g. “ground”) ? return current flows where? in cooperation with Interference mechanisms in installations 12 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 6 “Pig-tails” destroy good coax properties effect of geometry changes: fields outside interconnections; CM currents “Coax is better when than compared… twin wires” Coax Pig-tail destroys cable symmetry Fields are generated Twin wires ZT goes UP in cooperation with Interference mechanisms in installations 13 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Whether Pacemakers are Indeed this Susceptible? fields up to 30 kV/m and not just 50 Hz! in cooperation with Interference mechanisms in installations 14 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 7 ElectroStatic Discharge charges built on persons or equipment cause electric sparks (and currents) in cooperation with Interference mechanisms in installations 15 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Electric charging by induction direct contact not necessary! Wool -------------------Teflon 1. Charging of an insulator Printed Circuit Board ------------ --------------------- ++++++++++++++++ 2. Insulated PCB on charged surface in cooperation with Interference mechanisms in installations 16 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 8 Electric charging by induction direct contact not necessary! --------------------------------- ++++++++++++++++ 3.Touch or Ground PCB: negative charge disappears (spark) (PCB possibly damaged) VPCB QPCB CPCB (CPCB decreases) ++++++++++++++++ ----------------- 4. Lift PCB: voltage increases! Sparks fly! in cooperation with Interference mechanisms in installations 17 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Ground self-induction and a fast discharge edge “Grounding” or “short-circuit” of an ESD source is difficult (better avoid!) neon lamp flashes on discharge over “long” grounding path in cooperation with Interference mechanisms in installations 18 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 9 Front Door / Back Door EMI Front Door: Via Intended Coupling; Back Door: Via Unintended Coupling 100 [MHz] in-band interference 9 [MHz] out-of-band interference Receiver 87 - 108 [MHz] Front Door Back Door CM Mains Cord in cooperation with Interference mechanisms in installations 19 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Experiment with Frequency Controlled Motor PWM Controller crosstalk between cables due to transfer-impedance Cable 1 (source) DC Motor (twin wires) mode Plastic support 50 50 AC supply Cable 2 (passive) in cooperation with Interference mechanisms in installations 20 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 10 Power Quality: influence of power-users EMI related; Compatibility required “Voltage Quality” or “Quality of Supply” Various Power disturbances Conducted Susceptibility Power Supply Mains Generator Conducted Emissions Power Line Power User User Load Fluctuations Other users “Current Quality” or “Quality of Consumption” Reference: Bollen, Math H.J. “Understanding Power Quality Problems”, IEEE Press, 2000 ISBN 0-7803-4713-7, IEEE Order Number PC5764 in cooperation with Interference mechanisms in installations 21 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Non-Sinusoidal Currents and Ohm’s Law the root cause of most power-quality related problems User Load Current Original Mains Voltage User Mains Voltage V = I x RLINE in cooperation with Interference mechanisms in installations 22 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 11 Mains Voltage and Current as Users Like to See It clean sine wave voltage and resistive load in cooperation with Interference mechanisms in installations 23 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. History: Reactive Loads result: phase shift, cosine() reactive power im re true or real power in cooperation with Interference mechanisms in installations 24 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 12 Today: Non-Linear Loads most prominent: diodes charging bulk capacitors Legend Mains Voltage Mains Current in cooperation with Interference mechanisms in installations 25 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Modern Compact Fluorescent Lamp (CFL) electronic circuit with diode bridge and bulk capacitor Diode Bridge Bulk Capacitor Current Waveform on a “Decent” Sine-Shaped Voltage Waveform Source: Wikipedia in cooperation with Interference mechanisms in installations 26 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 13 Problem with Diode Rectifiers: Synchronicity all conduct simultaneously on mains voltage! distortion adds up Same Fluorescent Lamp in Large Office Building with distorted Voltage in cooperation with Interference mechanisms in installations 27 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Small Users <75 W Have No PF Requirements e.g. all LED’s , CFL’s and many laptops are exempt Effect…. Heavily Distorted Voltage Waveform This effect is called: Harmonic Distortion Multiple Zero Crossings in cooperation with Wave-Shape in Large Office Building: Multiple Zero Crossings! UNIVERSITY OF TWENTE. 28 Interference mechanisms in installations TELECOMMUNICATION ENGINEERING. 14 Monitor synchronous noise on the mains special interface box that filters out frequencies below 2 kHz The filter is intended for measurements from 2 – 150 kHz (high cutoff around 3 MHz) in cooperation with Interference mechanisms in installations 29 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Questionnaire Please fill out the questionnaire (enquete) sent as a separate MSWord file and mail it to the address shown there. In return we will send you the schematic diagram of the noise monitoring box (CM & DM) shown on the previous slide! Thank you! in cooperation with Interference mechanisms in installations 30 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 15 Mapping of EMC on Power Quality (User Aspects) users on the grid are sources and victims, the grid is the coupling path! User 1 User 2 SOURCE Source Emission coupling path Victim VICTIM Grid Susceptibility (Immunity) Coupling path: always electrical interconnections in cooperation with Interference mechanisms in installations 31 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Problem 1: Synchronous Peaks Add Up initial power budget new office building exceeded almost twofold • • • • in cooperation with Estimated required power: 3 MW Initial installation: 4 MVA (4 x 1 MVA) Installation upgraded to: 7.2 MVA (+ 2 x 1.6 MVA) Question: are we or are we not saving cost and energy? Interference mechanisms in installations 32 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 16 Problem 2: Switcher Frequencies Pollute Environment Source: YouTube low power fast switching requires short risetime IGBT’s and MOSFETs in cooperation with Interference mechanisms in installations 33 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. CM currents can be produced elsewhere if you connect your system to the outside world, currents will flow Situation indetector: practice AM-radio (Mains cord 1) Unit 1 (Mains cord 2) (I/O cable 1-2) Unit 2 Icm (noise current) “Ground 1” “Ground 2” loop closes through “ground” in cooperation with Interference mechanisms in installations 34 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 17 CM currents can be produced elsewhere fields in the environment are converted into CM currents Situation indetector: practice AM-radio (e.g. Mains cord 1) Unit 1 (e.g. Mains cord 2) (I/O cable 1-2) Unit 2 Icm (noise current) loop closes through “the air” (antenna-currents) in cooperation with Interference mechanisms in installations 35 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. End of Part I in cooperation with Interference mechanisms in installations 36 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. 18