Todd H. Hubing Michelin Professor of Vehicular Electronics Clemson University

Transcription

1 Lightning and Lightning Protection Todd H. Hubing Michelin Professor of Vehicular Electronics Clemson University

2 Course Topics Lightning Formation Lightning Safety Lightning Protection 2007 Lightning Lecture T. Hubing 2

3 Dielectric Breakdown V V 2007 Lightning Lecture T. Hubing 3

4 Dielectric Breakdown V V 2007 Lightning Lecture T. Hubing 4

5 Dielectric Breakdown V V 2007 Lightning Lecture T. Hubing 5

6 Dielectric Breakdown V V 2007 Lightning Lecture T. Hubing 6

7 Dielectric Breakdown V V 2007 Lightning Lecture T. Hubing 7

8 Dielectric Breakdown PLASMA V V 2007 Lightning Lecture T. Hubing 8

9 Lightning Formation Warm Humid Air 2007 Lightning Lecture T. Hubing 9

10 Lightning Formation Water Droplets Warm Humid Air 2007 Lightning Lecture T. Hubing 10

11 Lightning Formation Ice Crystals Water Droplets 2007 Lightning Lecture T. Hubing 11

12 Charge Separation Ice Crystals Water Droplets 2007 Lightning Lecture T. Hubing 12

13 Charge Separation 2007 Lightning Lecture T. Hubing 13

14 Charge Separation 2007 Lightning Lecture T. Hubing 14

15 Stepped Leaders 2007 Lightning Lecture T. Hubing 15

16 Streamers 2007 Lightning Lecture T. Hubing 16

17 Attachment 2007 Lightning Lecture T. Hubing 17

18 Return Stroke 2007 Lightning Lecture T. Hubing 18

19 Mean Number of Thunderstorm Days in the United States Lightning Lecture T. Hubing 19

20 Lightning Statistics Peak currents are generally 10 ka to 20 ka, but may exceed 100 ka. First strokes generally have more current than subsequent strokes Lightning Lecture T. Hubing 20

21 Lightning Statistics Approximately 2000 thunderstorms are in progress in the world at any given time. Commercial aircraft are struck by lightning every 5,00010,000 flying hours (on average) Lightning Lecture T. Hubing 21

22 Boeing 747 over Narita Airport 2007 Lightning Lecture T. Hubing 22

23 Lightning Statistics Lightning kills approximately 100 people in the U.S. every year Lightning Lecture T. Hubing 23

24 Lightning Dangers Electrical Shock Burns Secondary Effects 2007 Lightning Lecture T. Hubing 24

25 Where is the safest place to be in a thunderstorm? a) at home, taking a shower b) in your car, talking on your cell phone Lightning Lecture T. Hubing 25

26 Where is the safest place to be in a thunderstorm? a) on a golf course b) standing under a power line c) standing under a tree d) in a Boeing 777 flying through the storm 2007 Lightning Lecture T. Hubing 26

27 You re in a canoe in the middle of a large lake when a thunderstorm approaches. What should you do? a) row towards shore b) prop your paddle up in one end of the canoe and crouch down in the other c) swim towards shore d) turn the canoe over and get under it 2007 Lightning Lecture T. Hubing 27

28 Part II: Lightning Protection Todd H. Hubing Michelin Professor of Vehicular Electronics Clemson University

29 Lightning Protection Protection from currents Protection from arcs 2007 Lightning Lecture T. Hubing 29

30 Lightning Protection 2007 Lightning Lecture T. Hubing 30

31 Lightning Protection 2007 Lightning Lecture T. Hubing 31

32 Lightning Rods 2007 Lightning Lecture T. Hubing 32

33 Lightning Rods 2007 Lightning Lecture T. Hubing 33

34 Lightning Rods Cone of protection 2007 Lightning Lecture T. Hubing 34

35 Lightning Protection PHONE LINE 2007 Lightning Lecture T. Hubing 35

36 Lightning Protection PHONE LINE ELECTRIC LINE 2007 Lightning Lecture T. Hubing 36

37 Lightning Protection PHONE LINE ELECTRIC LINE 2007 Lightning Lecture T. Hubing 37

38 Lightning Protection PHONE LINE ELECTRIC LINE 2007 Lightning Lecture T. Hubing 38

39 Lightning Protection PHONE LINE ELECTRIC LINE 2007 Lightning Lecture T. Hubing 39

40 Lightning Protection PHONE LINE ELECTRIC LINE 2007 Lightning Lecture T. Hubing 40

41 Building Ground All wires and pipes that connect the inside of the building to the outside should have a common ground. PHONE LINE ELECTRIC LINE PLUMBING 2007 Lightning Lecture T. Hubing 41

42 Building Ground All wires and pipes that connect the inside of the building to the outside should have a common ground. PHONE LINE ELECTRIC LINE PLUMBING Note: This doesn t include the lightning rod ground, since this does not enter the building Lightning Lecture T. Hubing 42

43 Building Ground All wires and pipes that connect the inside of the building to the outside should have a common ground Lightning Lecture T. Hubing 43

44 Inductance Lightning currents will prefer a low inductance (straight) path Lightning Lecture T. Hubing 44

45 Lightning Protection for Aircraft Relying of Faraday Cage to protect everything inside Lightning Lecture T. Hubing 45

46 Lightning Protection for Boats Provide a safe current path to the water Lightning Lecture T. Hubing 46

47 Primary Lightning Protection Protection where a cable penetrates the building PHONE LINE 2007 Lightning Lecture T. Hubing 47

48 Arc Suppressors 2007 Lightning Lecture T. Hubing 48

49 Gas Discharge Tubes 10 s of volts to 1000 s of volts High Energy Low Capacitance (< 1 pf) Fail open Crowbar device 2007 Lightning Lecture T. Hubing 49

50 Thyristors 0.5 volts to 10 s of volts Medium Energy Higher Capacitance (10 s of pf) Fail open or short Crowbar device 2007 Lightning Lecture T. Hubing 50

51 Varistors 0.5 volts to 10 s of volts Low Energy Higher Capacitance (10 s of pf) Usually fail short Voltage limiting device 2007 Lightning Lecture T. Hubing 51

52 Diodes 0.5 volts to ~10 volts Lowest Energy High Capacitance (10 s of pf) Usually fail short Voltage limiting device 2007 Lightning Lecture T. Hubing 52

53 Course Summary Lightning Formation Lightning Safety Lightning Protection 2007 Lightning Lecture T. Hubing 53