Lightning Protection Seminar

8/3/2019 Lightning Protection Seminar

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Power SystemPower System Causes for OverCauses for OverVoltage and PreventionVoltage and Prevention

Seminar Presented by:Seminar Presented by:

SS MuraliMurali KrishnanKrishnan50509100615050910061 BTechBTech EEEEEE

SRM University,SRM University,

ChennaiChennai


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Power SystemPower System Causes for OverCauses for OverVoltage and PreventionVoltage and Prevention

TerminologyTerminology

Normal


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Power SystemPower SystemAbnormalitiesAbnormalities

1. Voltage Drop/ Shot interruptions 2.Harmonic waves due to voltage changes3.Temporary voltage increases 4.Switching surges 5. Lightning surges


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1.The voltage fallsbelow normal: Sag

2.The reverse of asag: Swell

3.Increase in voltage above110% of nominal for more than

one minute - Over-voltage.



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4.Noise - used to describe very

small and persistentdisturbances. These do not havedamaging effects but can be anuisance

5.Harmonics are a recurringdistortion of the waveform that

can be caused by various devicesincluding variable frequencydrives, non-linear power supplies

and electronic ballasts.



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6. When the voltage dropsbelow 10% of its nominalvalue it is called aninterruption or a blackout.

7. Transients are very short

duration (sub-cycle) events of varyingamplitude. Often referred to as"surges", transients are probablymost dangerous power abnormally



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External Causes:

Lightning - Direct hitDistant Lightning - Transients on Utility linesBrownouts/Blackouts - Sags & Recovery GridSwitching - Utility switching

Other Users - Adding/Removing loads line

Power SystemPower System Causes forCauses forTransientsTransients


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Internal Causes:

Switching of:Electrical motorsElevator MotorsCompressorsWelding or heavy machineryPower Overloads

Power SystemPower System Causes forCauses forTransientsTransients


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Power SystemPower System Lightning typesLightning types

Stepped LeaderStepped Leader StreamerStreamer


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A strike can averageA strike can average 100 million volts100 million volts ofof

electricityelectricity

Current of up toCurrent of up to 100,000100,000 amperesamperes

Can generateCan generate 54,00054,000oo

FF Lightning strikes somewhere on the EarthLightning strikes somewhere on the Earth

every secondevery second

Kills 100 US residents per yearKills 100 US residents per year

Power SystemPower System--FactsFacts --LightningLightning


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Direct strikeSide Flash

Power SystemPower System--Lightning EffectsLightning Effects


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Once the building is struck, lightning current can causedamage either by spark over or intrusion through service lines



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Lightning generatesstrong

electromagneticradiation in a broadband of frequencies



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Once entered into nearby structures, these radiation may damage

sophisticated electronics irrespective of whether they are in operationor not



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A service line may directly encountered with lightning or a nearby hitmay induced large voltage pulses in the service line



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SafeZone

Degradation

Catastrophe

Failure

Power SystemPower System--Transient EffectsTransient Effects


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Random faults (Annoying)

Memory LossData ErrorsRandom System Halts

Degradation (Un-noticed Damage)Break-Down of ICsLoss of Circuit Traces, or InsulationShortening of Component

Thermal Runaway of Semi-ConductorsBurn-Out (Catastrophic Failure)

Board Damage & Failure

System DownSystem Failure



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Damage to a modem card

The surge has come throughthe communication line. In

this case the damage to themodem has prevented furtherdamage to the computer



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Power SystemPower System--Lightning typesLightning types Two types of LightningTwo types of Lightning Direct & IndirectDirect & Indirect

DirectDirect Stroke AStroke A--Cloud to tall objectCloud to tall object protectionprotection

is possible, Stroke Bis possible, Stroke B--Between cloudsBetween clouds--protectionprotection

not possiblenot possible


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Power SystemPower System--Lightning typesLightning types IndirectIndirect Line directly below the cloud getsLine directly below the cloud gets electrostaticallyelectrostatically charged.charged.

When the cloud discharges to earth throWhen the cloud discharges to earth thro lighhtninglighhtning,, --veve charge on thecharge on the

line gets isolated and it travels fast on the line in both direcline gets isolated and it travels fast on the line in both directions in thetions in theform of waves. Indirect lightning is the major cause for transieform of waves. Indirect lightning is the major cause for transients innts in elecelec

lineslines


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Power SystemPower System--Lightning ProtectionLightning Protection

OH grounding wireOH grounding wire

Lightning arresterLightning arrester

EarthingEarthing screenscreen


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Power SystemPower System--Lightning ProtectionLightning Protection OH grounding wireOH grounding wire


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Power SystemPower System--Lightning ProtectionLightning Protection Lightning arresterLightning arrester


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Power SystemPower System--Lightning ProtectionLightning Protection EarthingEarthing screenscreenA grid of earthedA grid of earthed

copper conductorscopper conductors crisscriss crossing thecrossing the

Substation provide a low resistanceSubstation provide a low resistancepath forpath for lightningslightnings. They do not. They do not

guard againstguard against

travellingtravelling

waveswaves


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Power SystemPower System--Lightning ArrestersLightning Arresters Rod gapRod gap

Horn gapHorn gap

MultigapMultigap

Expulsion typeExpulsion typeValve typeValve type

Rod gapRod gap


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Power SystemPower System--Lightning ProtectionLightning Protection Horn gapHorn gap

MultigapMultigap


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Expulsion TypeExpulsion Type


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Valve TypeValve Type


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Susceptibility of components to damageSusceptibility of components to damage..

Motors & Transform.

Relays

Valves

Passive components

Diodes

Transistors (power)

Integrated circuit ICs

Semi-conductor diodes

10 1010 10 1010 1010 10-8 -6 -4 -2 0 2 4 6 8 J

No damage Possible damage Destruction


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Protecting Equipment AgainstProtecting Equipment Against

TransientsTransients


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Lightning Current: PeakLightning Current: Peak

ValueValue

Typical value for the first stroke is 30 kATypical value for the first stroke is 30 kA

Typical value for the subsequent strokeTypical value for the subsequent strokeis 15 kAis 15 kA

Values over 250 kA has been recordedValues over 250 kA has been recorded


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Power SystemPower System--Peterson CoilPeterson Coil


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Power SystemPower System--Peterson CoilPeterson Coil


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Power SystemPower System--Peterson CoilPeterson Coil -- samplesample


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Diverting surge current to earthDiverting surge current to earth

Principles of SurgePrinciples of Surge

Protection DevicesProtection Devices

Does NOT prevent lightning but protectsDoes NOT prevent lightning but protects

against effectsagainst effects

Clamping output voltage to a safe levelClamping output voltage to a safe level


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A protector performs like a switch controlled by voltage.If the voltage is higher than the rated voltage of the

electrical line to be protected, then the protector changesits state to low impedance and derives current to earth.The usual state of the protector is being in highimpedance, so that the protector is transparent for theinstallation.

Principle of Power Protection


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Exa

mpl

esfor

typic

alU

pvalu

es


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Surge protection devicesSurge protection devices

Spark gaps (air gaps)Spark gaps (air gaps)

Gas discharge tubes (Gas discharge tubes (GDTsGDTs))

ZenerZener diodes (avalanche diodes)diodes (avalanche diodes)

Metal oxideMetal oxide varistorsvaristors ((MOVsMOVs))

TransobersTransobers RelaysRelays

FusesFuses

PTCR (Positive Temperature Coefficient Resistor)PTCR (Positive Temperature Coefficient Resistor)

TBU (Transient Blocking Unit)TBU (Transient Blocking Unit)


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MOV/GDT/SADMOV/GDT/SAD

MOV

GDT

SILICON DIODE


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EarthingEarthing for lightning protectionfor lightning protection

-- principlesprinciples

Divert current as soon as possible

Use dedicated low impedance connection

Make sure other systems are bonded to it,

once!


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Clean and unclean lines should not be placed togetherClean and unclean lines should not be placed together


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Clean and unclean lines should not be placed togetherClean and unclean lines should not be placed together


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Bundled wires introduce much less voltageBundled wires introduce much less voltage


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Bundled wires introduce much less voltageBundled wires introduce much less voltage

drop than unbundled wiresdrop than unbundled wires


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Details ofDetails ofSPDsSPDs


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Two electrodes, close together, enclosed in a tube filledTwo electrodes, close together, enclosed in a tube filledwith gaswith gas

When the voltage rises, a low impedance arc is formedWhen the voltage rises, a low impedance arc is formed

between the two electrodesbetween the two electrodes

Symbol:Symbol:

Also called gasAlso called gas--filled surge arresterfilled surge arrester

Gas Discharge ArrestersGas Discharge Arresters


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Gas Discharge ArrestersGas Discharge Arresters


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Variable resistorVariable resistor resistance depends onresistance depends on

voltagevoltage Symbol:Symbol:

The most common type ofThe most common type of varistorvaristor is theis the MMetaletal

OOxidexide VVaristoraristor, or MOV, or MOV

Metal OxideMetal Oxide VaristorVaristor


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MOVsMOVs

Sili A l h Di dSili A l h Di d


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Semiconductor devices with similarSemiconductor devices with similar

characteristics to varistorscharacteristics to varistors

Symbol:Symbol:

Also calledAlso called transorbstransorbs andand clampingclamping

diodesdiodes

Silicon Avalanche DiodesSilicon Avalanche Diodes

Sili A l h Di dSili A l h Di d


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Silicon Avalanche DiodesSilicon Avalanche Diodes


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Surge Arrester CharacteristicsSurge Arrester Characteristics

BestBestGoodGoodBadBadCapacitanceCapacitanceBestBestGoodGoodFairFairLeakage currentLeakage current

BadBadFairFairGoodGoodCurrent sharingCurrent sharingGoodGoodBestBestGoodGoodLifespanLifespan

BestBestBadBadGoodGoodSurge ratingSurge ratingBadBadBestBestGoodGoodLetLet--through voltagethrough voltage

GDAGDASADSADMOVMOV


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Documents

Lightning Protection Seminar