Direct-stroke lightning protection per IEEE 998 and IEC 62305-3
Masts and shield wires placed by the design and checked by the rolling sphere method, with the sphere radius per protected level. The method applies on both standards sets. Sheets follow the set: A1 or ANSI D.
Shielding calculations and documents
The design places the masts and shield wires. It then checks the protected levels against the rolling-sphere envelope. Their electrodes go to the earth mat.
- Rolling sphere per IEEE 998-2012, with the modified electrogeometric model (Mousa)
- LPL I sphere per IEC 62305-3 for the MV outdoor areas and the building
- Corona radius, surge impedance, allowable stroke current and striking distance per protected level
- Coverage check per protected level
- Mast and shield-wire placement by the design
- Masts clear of roads and building footprints
- Electrodes at the masts and shield-wire towers, in the earth mat
- Lightning protection layout and sections in DXF and PDF
- Calculation report in PDF
Results, 220/33 kV pooling substation
The protected levels are covered. Sample design per IEC, CEA and CBIP.
- Lightning masts
- 14, 25.0 m
- Shield wires
- 5, at 18.5 m
- Shield-wire towers
- 10
- Electrodes
- 48
- Margin, HV tubular bus
- 8.09 m
- Margin, HV equipment
- 11.17 m
Equation, input values, result and clause per step
The calculation trail shows how the design reaches its sphere radius, its masts and wires and its coverage.
- 1Corona radius (HV tubular bus)IEEE 998-2012 §6.5, §6.6 (rolling sphere, Mousa)h 9.00 m, BIL 1050 kVp, E0 1500 kV/mRc = 0.145 m
- 2Surge impedance under coronaIEEE 998-2012 §6.5, §6.6 (rolling sphere, Mousa)r 57.1 mmZs = 315.9 Ω
- 3Allowable stroke currentIEEE 998-2012 §6.5, §6.6 (rolling sphere, Mousa)BIL 1050 kVp, Zs 315.9 ΩIs = 7.31 kA
- 4Striking distance (sphere radius)IEEE 998-2012 §6.5, §6.6 (rolling sphere, Mousa)k 1S = 29.15 m (other levels: HV equipment 29.0 m, ICT bushing tops 28.0 m, 33 kV outdoor areas 20.0 m, Control building roof 20.0 m)
- 5Shield wiresDesign rule10 towers5 wires at 18.5 m
- 6Lightning mastsDesign rulemast height 25.0 m14 masts at 25.0 m
- 7Coverage checkIEEE 998-2012 §6.5, §6.6 (rolling sphere, Mousa)5 levels, least margin +0.22 m5 of 5 levels protected
Lightning protection layout and sections
Documents of a sample project, generated by SubstationLayout and marked as samples. Not for construction.
Lightning protection calculation report
The report states the sphere radius per level, the electrogeometric model, the shielding, the coverage check and the earthing.
