2011 EMC Directory & Design Guide - Interference Technology

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testing & test equipment Hi g h P o w e r El e c t r o m a g n e t i c Thr e at s t o t h e Smart Grid [1,7]. Based on research performed over the years, it has been concluded that the E1 and E3 HEMP are the biggest concerns to the power system due to their high peak field levels and efficiency in coupling to power and control lines. They both have an area coverage that can exceed several thousand kilometers from a single burst. The concern is that these high-level electromagnetic fields and their area coverage will create simultaneous problems for computers and other electronic systems on the Earth’s surface, including the critical infrastructures (power, telecommunications, transportation, finance, water, food, etc.). This was the focus of the U.S. Congressional EMP Commission studies [8, 9]. Figure 4. Indication of the area exposed to E1 HEMP from a high-altitude burst over the central United States for various burst altitudes given in km. EMI, RFI, EMC & RadaR TuRnTablEs STANDARD 5 YEAR WARRANTY ON ALL MACTON PRODUCTS! ing field levels of 50 kV/m within 10 ns, the intermediate-time (E2) HEMP reaching 100 V/m between 1 microsecond and 1 second, and the late-time (E3) HEMP reaching 40 V/km for times between 1 and several hundred seconds Custom Engineered Antenna and Radar Profiling Positioning Equipment • Indoor and outdoor applications • systems ranging up to 60’ in diameter • 100–ton capacities • Variable speed control capabilities and positioning accuracy of ±0.001° • dozens of military and private contractor installations Extreme geomagnetic storm background The first two high-power threats and environments discussed above are man-made. There is, however, a natural environment known as an extreme geomagnetic storm that has strong similarities (spatial distribution and time variation) to the late-time (E3) portion of the HEMP [10]. Because of this, the protection methods are also very similar, although the specification levels of protective devices may vary. It should be noted that the term extreme geomagnetic storm is used here to indicate that the level of the storm exceeds the usual description by NOAA of a severe geomagnetic storm, which may occur more than once during a solar cycle (11 years). The extreme geomagnetic storm is defined as a 1 in 100 year storm [8]. In brief, a large increase in charged particles ejected from the Sun and into the solar wind can interact with the Earth’s magnetic field and produce a significant distortion of the geomagnetic field at the surface of the Earth. This rapid variation of the geomagnetic field (on the order of seconds to minutes) induces time varying electric fields in the Earth, which through the neutrals of transformers create time-varying (yet quasi-dc relative to 60 Hz) currents in the high-voltage power network. These currents induce severe harmonics, increase inductive 50 interference technology emc Directory & design guide 2011
R a da s k y testing & test equipment load and produce heating in each exposed transformer. This can lead to voltage collapse of the network as experienced by the power grid in Quebec in March 1989 and damage to highly exposed transformers. Figure 3 illustrates the contours of the B-dot environment at the Earth’s surface (in nT/min), minutes after the collapse of the Quebec power network. The spatial extent of the severe fields is quite large, and the footprint can move (and has moved) further south during other storms. For additional information about geomagnetic storms and their impact on power grids, one should consult the literature [11, 12]. Potential Impacts of HPEM with the Power Grid Early-time (E1) HEMP impacts The early-time (E1) HEMP produces a fast rising and narrow electric field pulse (2.5/25 ns) that propagates at the speed of light from the burst point. Figure 4 illustrates that the area coverage depends on the burst height. Due to the rapid rise of the E1 HEMP in the time domain, the frequency content is much higher in magnitude and frequency than lightning electromagnetic fields and normal substation electric fields produced by switching events in the high voltage yard. These electromagnetic fields can couple to low voltage control cables in a substation and propagate levels on the order of 20 kV to the control house electronics. This presents a severe disturbance to existing substation solid-state protective relays. In addition, the EM fields are high enough also to penetrate the walls of most substation control houses, as the walls are not designed to attenuate EM fields significantly (as shown in Table 1). As more Smart Grid electronics are placed in substations, these E1 HEMP fields become a significant concern to their performance. Also the placement of new Smart Grid communication antennas and electronics in substations should consider the threat of E1 HEMP. It is noted that microwave towers with their long cables extending to the ground are an ideal pickup geometry for E1 HEMP fields, and unless good grounding practices (circumferential bonding) are employed at the entrance of the cables to communications buildings, the high-level induced E1 HEMP currents and voltages will propagate efficiently to the cable connections of the electronics, creating likely damage. E1 HEMP will also couple efficiently to aboveground medium and low voltage power lines that are typical for the distribution grid and also to the low voltage drop lines to homes or businesses. While burial of distribution lines is becoming more common in the U.S., there are still on the order of 70% of U.S. distribution lines at medium voltage that are above ground. The problem with this is that the E1 HEMP can couple voltages up to 1 MV common mode with Shielding Measurements Normal Shielding, dB Room Shielding, dB 0 All wooden building 2 Room under wood roof 4 5 Wood Bldg-Room 1 4 Concrete - no rebar 5 Wood Bldg-Room 2 6 10 Concrete + rebar-room1 7 Concrete + rebar-room2 11 Concrete + rebar-room3 11 20 Concrete + rebar-room4 18 Metal bldg. 26 30 Concrete + well-prot. room 29 Table 1. Shielding effectiveness measurements for various power system buildings and rooms. a rise time of 10 ns and a pulse width of 100 ns [13]. These levels will create insulator flashover on many distribution lines (simultaneously) and can cause mechanical damage to some insulators [14]. For the shorter drop lines to homes, interferencetechnology.com interference technology 51
Page 1: TM 2011 EMC Directory & Design Guid
Page 6: contents2011 Interference Technolog
Page 10: from the editor A look back — and
Page 14: testing & test equipment sions is a
Page 17 and 18: CPI: Powering your world. TWTAs for
Page 20 and 21: testing & test equipment Troublesho
Page 22 and 23: testing & test equipment Troublesho
Page 24: testing & test equipment Wir e l e
Page 27 and 28: Viol e t t e testing & test equipme
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Page 32: testing & test equipment M e a s ur
Page 35 and 36: H o o l ih a n testing & test equip
Page 38 and 39: testing & test equipment O n t h e
Page 40 and 41: New Military Product Highlights IFI
Page 42: testing & test equipment O n t h e
Page 45 and 46: R o drigue z testing & test equipme
Page 47 and 48: R o drigue z testing & test equipme
Page 49 and 50: EMC EMI EMP EMR EMV ESD EMCON HERF
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Page 60: testing & test equipment N e w EMC
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Page 69 and 70: Facility Solutions Facility Solutio
Page 71 and 72: EMI/RFI Shielding Solutions Our ext
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Page 82: shielding / cables & connectors Num
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surge & transients A Risk A s s e s
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surge & transients A Risk A s s e s
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filters A c c ur at e F e e d t hr
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filters M e a s ur e m e n t s a b
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H o f f m a nn, Br aun, Frech, Rus
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design EMI Sources and Their Most S
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Cover_DDG10.indd 1 TM EMC Design ..
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standards recap HBM ESD parameters
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standards recap International Organ
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standards recap noise from power li
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standards recap quality on selected
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standards recap including to addres
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professional societies Every year,
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professional societies of TechAmeri
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professional societies education, s
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government emi/emc directory Mr. Ro
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government emi/emc directory Ms. Ja
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government emi/emc directory Chief:
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products & services index products
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products & services index Electrost
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products & services index Lightning
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products & services index York EMC
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company directory company directory
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company directory AR Tech Engineere
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company directory DARE!! Instrument
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company directory DNK Metric A/S...
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company directory Instruments For I
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company directory Metal Textiles Co
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