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Tutorial on electric, magnetic and electro-magnetic fields and possible technical disturbances hereby caused

Tutorial on electric, magnetic and electro-magnetic fields and possible technical disturbances hereby caused

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EMC EMC Presentation Transcript

  • Everything you always should know about high frequency
    Stefan Fassbinder
    Deutsches Kupferinstitut
    Am Bonneshof 5
    D-40474 Düsseldorf
    Tel.: +49 211 4796-323
    Fax: +49 211 4796-310
    sfassbinder@kupferinstitut.de
    www.kupferinstitut.de
  • The German Copper Institute, DKI, is the central information and advisory service dealing with all uses of copper and copper alloys. We offer our services to:
    • Commercial companies
    • The skilled trades
    • Industry
    • R & D institutes
    • Universities
    • Artists and craftsmen
    • Students
    • Private individuals
    We can be contacted by:
    • post
    • phone
    • fax
    • e-mail
    • internet
    • online database, or
    • personally
  • Complementary elements:Inductances and capacitances
  • What really is that,E = 1 V/m?
    The fieldstrength bet-ween any twoelectrodesat a spacing of d = 1 m,between whicha voltage of U = 1 Vis applied
  • What really is that,H = 1 A/m?
    I = 1 A
    A field line with a length of 1m around a conductor through which a 1A current is passing
    At a distance ofthere is a field strength of 1A/m
  • What really is a magnetic flux density of B = 1 T = 1 Vs/m² ?
    Iron length: E. g. 300 mm mean,µR = 300
    Corresponds to 600 mm iron altogether or2 mm air
    Field strengthwithin the core:
    within the gap:
    within the entire field, whereas:
    Air gap: E. g. 1 mm, µR = 1
  • Complementary elements: Inductances and capacitances
  • I
    I
    IL
    IC
    U
    U
    UL
    UC
    Complementaryelements
    Inductance:
    Current leads voltage by 90°
    or
    voltage lags behind current by 90°, respectively
    Capacitance:
    Current leads voltage by 90°
    or
    voltage lags by 90° behind current, respectively
  • Z
    R
    XC+ XL
    XCRXL
    Complementaryelements
    Result:
    180° Phase shift between voltages across or currents in L and C, respectively, so: Inductive und capacitive Reactances subtract linearly!Vectoral:
    Linear:
  • XCRXL
    Let us clarify some terms1. Resonance
  • i
    Howtoimaginethis?
  • i
    i
    i
    i
    i
    i
    Howtoimaginethis?
  • i
    i
    i
    i
    i
    i
    Howtoimaginethis?
  • i
    i
    i
    i
    i
    i
    Howtoimaginethis?
  • Serial resonant filters (acceptorcircuits)
    UR
    R
    U
    let the resonance frequency f0 pass without any reactance
    vectoral description
    L
    UL
    UC
    C
  • Attention: From outside you don't seewhat's going on inside!
    UR
    R
    U
    L
    UL
    UC
    Say:L and C do not limit the current!
    C
    I
  • Parallel resonant filters (rejectioncircuits)
    I≈0
    U
    block currents of the resonant frequency f0
    (vectoral description)
    C
    L
    R≈0
  • Attention: From outside you don't seewhat's going on inside!
    I≈0
    U
    There is practically no current flowing through the resonant circuit, but possibly a lot within the resonant circuit!
    C
    L
    R≈0
  • There are many LC pairs yielding the same resonant frequency, LF or HF…
    Reactor reactance
    Capacitor reactance
    Serial impedance
    Phase angle
  • …but L by C defines the behaviourin the rest of the frequency range!
    Reactor reactance
    Capacitor reactance
    Serial impedance
    Phase angle
  • …but L by C defines the behaviourin the rest of the frequency range!
    Reactor reactance
    Capacitor reactance
    Serial impedance
    Phase angle
  • The total energy stored within the resonant circuit remains the same
  • 2.Characteristicimpedance
    is calculated from the specific line dimensions:
    Longitundinal inductance L‘ and transversal capacitance C‘ per unit of length.
    Model of an electric transmission line:
  • Line with greatcharacteristic impedance:Line with low characteristic impedance:
  • Line with small charac-teristic impedance
    Speed of propagation: 299.792,5 km/s
  • Line with great charac-teristic impedance
    Speed of propagation: 299.792,5 km/s
  • By the way, how fast does current really flow?
    1 copper atom has 29 electrons. One of them is mobile.
    1 mole of copper (63.546 g equalling 7.108 cm³) contains 6.02*1022 atoms (Avogadro's Constant).
    1 g of copper thereby contains 9.47345*1021 electrons.
    So per gram 3.26671*1020 of them are mobile, this is 3.654*1019 per cubic centimetre.
    A current of 1 A means that at any point of the conductor 6.25*1018 electrons come flowing by (for each electron carries a charge of e = 1.9*10-19 As with it).
    With 16 A flowing in a 1.5 mm² residential installation cable this yields 0.8 mm/s.
    In case of short circuit it may be up to 50 mm/s!
  • Vital for assessing im-pulse waves reflections, e. g. at the interfaces between overhead and underground lines
  • Important in order to avoid reflections:
    Terminating resistor, e. g. inside an antenna socket designed as a pass-through outlet but then used as a terminating outlet.
    The amplitude of the terminating resistor has to equal the characteristic impedance, in this case e. g. 75 Ω:
  • Only applicable in information technology, of course! Or…
    Specific values of a 380 kV overhead line:
    Values of a 380 kV underground cable:
    VPE
    Oil
  • This would result in a »natural power« of…
    Forheaven'ssake!
  • 3. Limit frequencies,4. Bandwidth and hence5. the quality
    of a reactor,
    of a capacitor,
    a resonant circuit
  • 3. Limit frequencies f1 and f24. Bandwidth B
    f2
    f0
    f1
    B
    Reactorreactance
    Capacitorreactance
    Serial impedance
    Phase angle
  • 3. Limit frequencies f1 and f24. Bandwidth B
    f2
    f0è
    f1 è
    B
    Reactor reactance
    Capacitor reactance
    Serial impedance
    Phase angle
  • Rejectioncircuits
    Reactor reactance
    Capacitor reactance
    Serialimpedance
    Phase angle
  • 5. Quality is an issue,described by thequality factor Q
    What matters is the ratio of the reactive by the active share of the impedance, for active load means active power, and active power means
    • power loss
    • attenuation
  • Between line and high frequency: Sound frequency
    Which one is the right cable
    to carry the sound to the speaker?
  • 6.Interference
    Adding two
    voltages of
    50 Hz and 51 Hz
    and equal peak values
  • Direct voltage; low frequency:
    Electrical fields
    Direct current; low frequency:
    Magnetic fields
    High frequency (above ≈30 kHz):Electro-magnetic fields
  • Howtoimaginethis?
  • Howtoimaginethis?
  • Howtoimaginethis?
  • Howtoimaginethis?
  • Howtoimaginethis?
  • Howtoimaginethis?
  • Howtoimaginethis?
  • Howtoimaginethis?
  • Howtoimaginethis?
  • Howtoimaginethis?
  • Howtoimaginethis?
  • This is how to imagine this!
    These fields radiate andmay beused for transmittinginformation
    over shortand longdistances
  • …or they may disturb said transmissions!
    Well, if you don't apply any filters…
  • Thisbatteryoperatedthermometerlocated ≈30 cm off a fluorescentlampdiditsjobfairly well until
    displayedtheroomtemperaturefairly well until…
    …thelighthadbeenswitched a fewtimes – thenthedisplaysuddenlyturnedkryptic!
  • There are three types of coupling mechanisms
    Galvanic:
    Electrically conductive connection
    ê
    Electrons flow »personally« from source to sink.
    Sort of disturbance:PEN conductor, TN-C system
    Inductive:
    current
    ê
    magnetic field
    ê
    induction
    Capacitive:
    voltage
    ê
    electrical field
    ê
    influence
    NFNF
    HF
    Electro-magnetic fields,radiation / susceptibility (HF)
  • 1.Galvaniccoupling
    What does this gentleman want to show you here?
    The leading example of galvanic coupling:
    Multiple connections between N and PE, i. e. between energy and information technique (operational earth)
  • U
    2. Inductive coupling
    With operating currents: di/dt≈ 50 A/ms
    Signal level Cat. 3 data lines: 1 V
    Signal level Cat. 5 data lines: 500 mV
    Signal level 10Gbit/s beginning: 130 mV
    Signal level 10Gbit/s end: 600 µV!
    With short-circuit currents: di/dt≈ 1 kA/ms
    With switching transients: di/dt≈ 10 kA/ms
    In inverterdrives: di/dt≈ 50 kA/ms
    With lightning currents: di/dt≈ 50 kA/µs!
    l
    d
    ~
    I
  • 3.Capacitivecoupling
    I
    U
    I
  • 3.Capacitivecoupling
    I
    U
  • 3.Capacitivecoupling
    I
    U
    I
  • There are three of all evils: Coupling mechanisms in practice

    Inductive coupling:
    N against PE

    Capacitive coupling:
    MV against PE?
    Galvaniccoupling:
    »Second CEP«
    Only here it shall be
    è

  • Therefore:Mind the coupling mechanisms!
    Galvanic coupling:Once and only once (CEP)
    • Capacitive coupling:A very thin electricallyconductive layer suffices – if earthed!
    • Inductive coupling:Thick magneticallyconductive layers required!
  • And:Mindthereferencestocableducts in thestandards!
    Z. B. IEC 60364-4-44
    (DIN EN 50174-2 / VDE 0800-174-2)
  • And:Note thereferencesre-gardingthecablepositioning!
    Z. B. IEC 60364-4-44
    (DIN EN 50174-2 / VDE 0800-174-2)
  • Do not confuse:
    Analogueand digital cables
    Analogue cables have a screen.
    Digital cables have some-thing that looks like a screen.
  • How to deal with coupling mechanisms?
    By just dodgingthem!
    Differential mode:
    Savestrouble
    Common mode:
    Savescopper
  • Spicing things up with a pinch of HF: A piece of cake when using an electronic transformer
  • Any sort of radiation:Decorative HF reactors
  • The European Union
    has been providing a total of three million Euros over athree year period to enable experts from across Europeto co-operate in the development of the definitive internet site covering all aspects of power quality!
    To follow the latest developments visit
    www.leonardo-energy.org
    and take a look at the growing body of information that has been made available by the Leonardo Power Quality and the Leonardo Energy Initiatives.
    Our aim is to develop and disseminate teaching materials in 13 languages dealing with the detection, mitigation and management of EMC problems.
    Target groups include electrical technicians, engineers, those in the skilled trades, building system engineers, architects, planners as well as apprentice technicians and students and their teachers.
    At present the Power Quality Initiative has 165 members from commercial companies, institutions, universities and trade associations.
    We openly encourage other industrial and academic partners to participate in this project and welcome contributions at any time.
    Just log on!
    Awardedthreeprojects out of about4000 in December 2004 – one of thembeingtheLeonardo Power Quality Initiative