NamNgum5115kVSubstationLightingProtectSystemCalculationCONTENTS1.TOC\o"1-3"\h\z\uCalculationpurpose2.Calculationaccordance3.Calculationprocess4.ResultsPAGE\*MERGEFORMAT21.CalculationpurposeInthelightofcalculation,determinethedesignofLightingProtectSystemofNamNgum5115kVSubstation2.Calculationbasis(China)“CodeforDesignofLightningProtectionofBuildings”《GB50057-94》(China)“Over-VoltageProtectionandInsulationCoordinationofACElectricalInstallations”《DL-T620-1997》(China)“ElectricalDesignManualforElectricPowerEngineering”3.CalculationprocessOverheadgroundwireisusedinlightingprotectinNamNgum5115kVSubstation.ThescopeoflightningprotectionisshowninthedrawingofNN5-D0107-02。3.1SymbolTabletrxRadiusofprotection,mhHeightofoverheadgroundwire,mPCoefficientofheightimpact(whenh≤30m,P=1)hxHeightoftheprotectedobject,mHOThelowestprotectionheightbetweentwooverheadgroundwire,mDDistancebetweentwooverheadgroundwire,mbxMin.protectionwidthoftwooverheadgroundwire,m3.2Calculation3.2.1Calculationofprotectionwidthofsingleshiedwireoneachsideinhxhorizontalplanea)whenhx≥h/2rx=0.47(h-hx)Pb)whenhx<h/2rx=(h-1.53hx)PHere:h=14.8mp=1hx=12.3mBecauseofhx≥h/2Thus,rx=0.47(h-hx)P=1.175m3.2.2CalculationofProtectionscopeoftwoequalaltitudeandparalleloverheadgroundwirea)Thecalculationmethodofprotectionscopeofoutboardtwooverheadgroundwireshouldbedeterminedaccordingtosingleoverheadgroundwire.b)ThelowestprotectionheightbetweentwooverheadgroundwireandMin.protectionwidthoftwooverheadgroundwireshouldbecalculatedasfollow:：HO=h-D/4pbx=hO-hxHere:h=14.8mp=1hx=12.3mD=9mThus,HO=12.55mbx=0.25m4ResultsInthelightofabovecalculation,thelightingprotectsystermofNamNgum5115kVSubstationismeettherequirements。