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Lightning and Lightning Protection

Todd H. HubingMichelin Professor of Vehicular Electronics

Clemson University

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2007 Lightning Lecture T. Hubing 2

Course Topics

Lightning Formation

Lightning Safety

Lightning Protection

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2007 Lightning Lecture T. Hubing 3

- V +

V

Dielectric Breakdown

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2007 Lightning Lecture T. Hubing 4

Dielectric Breakdown

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V

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2007 Lightning Lecture T. Hubing 5

Dielectric Breakdown

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2007 Lightning Lecture T. Hubing 6

Dielectric Breakdown

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2007 Lightning Lecture T. Hubing 7

Dielectric Breakdown

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2007 Lightning Lecture T. Hubing 8

Dielectric Breakdown

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PLASMA

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2007 Lightning Lecture T. Hubing 9

Warm Humid Air

Lightning Formation

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2007 Lightning Lecture T. Hubing 10

Warm Humid Air

Water Droplets

Lightning Formation

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2007 Lightning Lecture T. Hubing 11

Water Droplets

Ice Crystals

Lightning Formation

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2007 Lightning Lecture T. Hubing 12

Water Droplets

Ice Crystals+

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--

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Charge Separation

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2007 Lightning Lecture T. Hubing 13

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Charge Separation

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2007 Lightning Lecture T. Hubing 14

- --

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Charge Separation

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2007 Lightning Lecture T. Hubing 15

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Stepped Leaders

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2007 Lightning Lecture T. Hubing 16

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Streamers

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2007 Lightning Lecture T. Hubing 17

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Attachment

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2007 Lightning Lecture T. Hubing 18

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Return Stroke

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2007 Lightning Lecture T. Hubing 19

Mean Number of Thunderstorm Days in the

United States

9040

40

40

50

5

20

510

20

20

4050

70

50

30

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2007 Lightning Lecture T. Hubing 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.

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2007 Lightning Lecture T. Hubing 21

Lightning Statistics

Approximately 2000 thunderstorms

are in progress in the world at anygiven time.

Commercial aircraft are struck bylightning every 5,000-10,000 flying

hours (on average).

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Boeing 747 over Narita Airport

2007 Lightning Lecture T. Hubing 22

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2007 Lightning Lecture T. Hubing 23

Lightning Statistics

Lightning kills approximately 100

people in the U.S. every year.

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2007 Lightning Lecture T. Hubing 24

Lightning Dangers

Electrical Shock

Burns

Secondary Effects

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2007 Lightning Lecture T. Hubing 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.

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2007 Lightning Lecture T. Hubing 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

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2007 Lightning Lecture T. Hubing 27

a) row towards shore

b) prop your paddle up in one end of thecanoe and crouch down in the other

c) swim towards shore

d) turn the canoe over and get under it

Youre in a canoe in the middle of a large lake

when a thunderstorm approaches. What shouldyou do?

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Part II: Lightning Protection

Todd H. HubingMichelin Professor of Vehicular Electronics

Clemson University

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2007 Lightning Lecture T. Hubing 29

Lightning Protection

Protection from currents

Protection from arcs

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2007 Lightning Lecture T. Hubing 30

Lightning Protection

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2007 Lightning Lecture T. Hubing 31

Lightning Protection

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2007 Lightning Lecture T. Hubing 32

Lightning Rods

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2007 Lightning Lecture T. Hubing 33

Lightning Rods

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2007 Lightning Lecture T. Hubing 34

Cone of protection

Lightning Rods

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2007 Lightning Lecture T. Hubing 35

PHONE LINE

Lightning Protection

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2007 Lightning Lecture T. Hubing 36

PHONE LINE

ELECTRIC LINE

Lightning Protection

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2007 Lightning Lecture T. Hubing 37

PHONE LINE

ELECTRIC LINE

Lightning Protection

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2007 Lightning Lecture T. Hubing 38

PHONE LINE

ELECTRIC LINE

Lightning Protection

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2007 Lightning Lecture T. Hubing 39

PHONE LINE

ELECTRIC LINE

Lightning Protection

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2007 Lightning Lecture T. Hubing 40

PHONE LINE

ELECTRIC LINE

Lightning Protection

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2007 Lightning Lecture T. Hubing 41

PHONE LINE

ELECTRIC LINE

PLUMBING

All wires and

pipes thatconnect theinside of thebuilding tothe outsideshould have acommon

ground.

Building Ground

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2007 Lightning Lecture T. Hubing 42

PHONE LINE

ELECTRIC LINE

PLUMBING

All wires and

pipes thatconnect theinside of thebuilding tothe outsideshould have acommon

ground.

Note: Thisdoesntinclude thelightning rod

ground, sincethis does notenter the

building.

Building Ground

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2007 Lightning Lecture T. Hubing 43

All wires and

pipes thatconnect theinside of thebuilding tothe outsideshould have acommon

ground.

Building Ground

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2007 Lightning Lecture T. Hubing 44

Lightning currents will prefer a low inductance

(straight) path.

Inductance

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2007 Lightning Lecture T. Hubing 45

Relying of Faraday Cage to protect everythinginside.

Lightning Protection for Aircraft

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2007 Lightning Lecture T. Hubing 46

Provide a safe current path to the water.

Lightning Protection for Boats

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2007 Lightning Lecture T. Hubing 47

Protection where a cable penetrates the building

PHONE LINE

Primary Lightning Protection

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2007 Lightning Lecture T. Hubing 48

Arc Suppressors

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2007 Lightning Lecture T. Hubing 49

10s of volts to 1000s of volts

High Energy

Low Capacitance (< 1 pF)

Fail open

Crowbar device

Gas Discharge Tubes

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2007 Lightning Lecture T. Hubing 50

0.5 volts to 10s of volts

Medium Energy

Higher Capacitance (10s of pF)

Fail open or short

Crowbar device

Thyristors

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2007 Lightning Lecture T. Hubing 51

0.5 volts to 10s of volts

Low Energy

Higher Capacitance (10s of pF)

Usually fail short

Voltage limiting device

Varistors

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2007 Lightning Lecture T. Hubing 52

0.5 volts to ~10 volts

Lowest Energy

High Capacitance (10s of pF)

Usually fail short

Voltage limiting device

Diodes

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Course Summary

Lightning Formation

Lightning Safety

Lightning Protection