Lightning Protection Seminar
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Transcript of 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.
Power SystemPower SystemAbnormalitiesAbnormalities
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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.
Power SystemPower SystemAbnormalitiesAbnormalities
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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
Power SystemPower SystemAbnormalitiesAbnormalities
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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
Power SystemPower System--Lightning EffectsLightning Effects
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Lightning generatesstrong
electromagneticradiation in a broadband of frequencies
Power SystemPower System--Lightning EffectsLightning Effects
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Once entered into nearby structures, these radiation may damage
sophisticated electronics irrespective of whether they are in operationor not
Power SystemPower System--Lightning EffectsLightning Effects
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A service line may directly encountered with lightning or a nearby hitmay induced large voltage pulses in the service line
Power SystemPower System--Lightning EffectsLightning Effects
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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
Power SystemPower System--Transient EffectsTransient Effects
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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
Power SystemPower System--Transient EffectsTransient Effects
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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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Power SystemPower System--Lightning ProtectionLightning Protection
Expulsion TypeExpulsion Type
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Power SystemPower System--Lightning ProtectionLightning Protection
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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