Specifications

c‐1
888‐2628‐300 WARNING:Disconnectprimarypowerpriortoservicing.
Copyright©2013,HarrisBroadcast
Maxiva ULX Series
November 11, 2013
Appendix-c
Grounding Considerations, Surge Protection
c
c.1 Surge and Lightning Protection
Alightningstormcancausetransientsinexcessof2kVtoappearonpowerorfieldsignallines.Thedurationofthese
transientsvariesfromafewhundrednanosecondstoafewmicroseconds.Powerdistributionsystemtransient
protectorscanefficientlyprotectthetransmitterfromtransientsofthismagnitude.Transientsareshunted
to
groundthroughtheprotectiondevicesanddonotappearontheoutput.Toprotectthetransmitterfromhigh
transientsonfieldcables,electronicsurgeprotectorsarerecommended.
Alllightningprotectionisdefensiveinnature,thatis,reactingtoalightningstrikethathasalreadyoccurred;
therefore,itseff ectivenessislimited.Nothingcanprovidetotalimmunityfromdamageinthecaseofadirect
lightningstrike.However,surgeprotectorsinstalledimmediatelyafterthemainpowerdisconnectswitchinthe

powerdistributionpanelwillaffordsomeprotectionfromelectricalsurgesinducedinthepowerlines.
Surgeprotectiondevicesaredesignedtooperateandrecoverautomatically.Whenoperatedwithinspecifications,a
surgeprotectordoesnotrequiretesting,adjustment,orreplacement.Allpartsarepermanentlyenclosedtoprovide
maximumsafetyandflexibilityofinstallation.
Toassurethesafetyofequipmentandpersonnel,primarypowerlinetransformersmustbeprotectedbylightning
arrestorsattheserviceentrancetothebuilding.Thiswillreducethepossibilitythatexcessivevoltageandcurrent
duetolightningwillseeksomelowimpedancepathtogroundsuchasthebuildingmetall ic
structureoran
equipmentcabinet.Themosteffectivetypeofpowerlinelightningprotectionistheoneinwhichasparkgapis
connectedtoeachprimary,secondary,andthecaseofthepowerlinetransformer.Eachsparkgapisthen
independentlyconnectedtoearthground.Incaseswheredriven
groundrodsareusedforbuildingground,the
primaryandsecondaryneutralsmustbeseparatedbyasparkgap.Iftwoseparategroundrodsareused,therods
mustbeatleast20feetapart.Allconnectionsbetweenlightningarrestors,lineconnections,andgroundmustbe
madeasshortandstraight
aspossible,withnosharpbends.
c.2 System Grounding
Signalsemployedintransmittercontrolsystemsareontheorderofafewmicrosecondsinduration,which
translatestofrequenciesinthemegahertzregion.Theyarethereforeradio‐frequencysignals,andmaybeatlevels
lessthan500microvolts,makingthemsusceptibletonoiseappearingongroundwiresoradjacentwiring.
Thus,all
groundwiringmustbelowinimpedanceaswellaslowinresistance,withoutsplices,andasdirectaspossible.Four
basicgroundsarerequired:
1. ACground
2. DCground
3. Earthground
4. RFground
c.2.1 Ground Wires
Groundwiresshouldbeatleastaslargeasspecifiedbythelocalelectricalcode.Theseleadsmustbelowimpedance
directruns,asshortaspossiblewithoutsplices.Inaddition,groundconductorsshouldbeinsulatedtoprevent
intermittentorunwantedgroundingpoints.
Connectiontotheearthgroundconnectionmustbemadewithcopperclampswhichhavebeenchemicallytreated
toresistcorrosion.Caremustbetakentopreventinadvertentgroundingofsystemcabinetsbyanymeansother
thanthegroundwire.Cabinetsmustbemountedonasupportinsulatedfromground.
c.2.2 AC Ground
Thesuggestedgroundingmethodconsistsoftwoseparatelystructuredgroundwireswhicharephysicallyseparated
fromeachotherbutterminateatearthground.ThegreengroundwirefromtheACpowerinputmustconnectto
thepowerpanelandthegroundstrapsoftheequipmentcabinets.