Lightning Risk Assessment Calculator | NFC 17-102 |
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LIGHTNING RISK ASSESSMENT
According to NFC 17-102
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Lightning Protection Systems
LIGHTNING RISK ASSESSMENT
Protection Level Selection - NFC 17-102 Standard
Structure Dimensions
C1 - Environment Coefficient
C2 - Structural Coefficient
Metallic Structure
Common Structure
Flammable Structure
C3 - Content Coefficient
C4 - Structure Occupancy
C5 - Lightning Consequences
Annual Average Thunder Days
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Lightning Protection Systems
Lightning Risk Assessment
Calculation of Protection Level - NFC 17-102
CALCULATION OF PROTECTION LEVEL
| FORMULAS | VALUES | RESULTS |
|---|---|---|
| The Equivalent Collection Area of Structure | L=50 | Ae=15061.7251 |
| Ae=L×W+6H(L+W)+πH² | W=30 | |
| (For rectangular fields) | H=15 | |
| Expended Lightning Frequency | Td=30 | Nc=0.0423 |
| Ng=0.04Td1.25 | Ng=2.8084 | |
| Nc=Ng×Ae×C1×10-6 | Ae=15061.7251 | |
| Accepted Lightning Frequency | C1=1 | Nd=0.0002 |
| C=C2.C3.C4.C5 | C2=0.5 | |
| Nd=5.5.10-5/C | C3=1 | |
| C4=1 | ||
| C5=5 | ||
| If Nd ≤ Nc →Optional Protection | ||
| Efficiency , E=1-(Nd/Nc) | ||
Efficiency
E= 0.95
0.95 ≤ E < 0.98
Protection Levels
LEVEL I | I
Active | Faraday Cage
Piezoelectric Crystal Active Lightning Conductor Selection Table
| Ng | ∆T=15μs | ∆T=30μs | ∆T=45μs | ∆T=60μs |
|---|---|---|---|---|
| H(m) | I | II | III | IV |
| 2 | 13 | 15 | 18 | 20 |
| 4 | 25 | 30 | 36 | 41 |
| 5 | 32 | 37 | 45 | 51 |
| 6 | 32 | 38 | 46 | 52 |
| 8 | 33 | 39 | 47 | 54 |
| 10 | 34 | 40 | 49 | 56 |
| 20 | 35 | 44 | 55 | 63 |
| 30 | 35 | 45 | 55 | 69 |
| 60 | 35 | 45 | 60 | 75 |
Selection table for electrostatic active lightning conductor
| Ng | ∆T=30μs | ∆T=45μs | ∆T=60μs |
|---|---|---|---|
| H(m) | I | II | III |
| 2 | 19 | 22 | 25 |
| 4 | 38 | 44 | 51 |
| 5 | 48 | 55 | 63 |
| 6 | 48 | 55 | 64 |
| 8 | 49 | 56 | 65 |
| 10 | 49 | 57 | 66 |
| 20 | 50 | 59 | 71 |
| 30 | 50 | 60 | 73 |
| 60 | 50 | 60 | 80 |
According to level of Faraday Cage Protection System Criteria
| Protection Levels | Down conductor distance |
|---|---|
| I | 10 |
| II | 10 |
| III | 15 |
| IV | 20 |
Angle and height level of protection depends α
| Protection Level | Sphere radius (m) | Cage Size |
|---|---|---|
| I | 20 | 5x5 |
| II | 30 | 10x10 |
| III | 45 | 15x15 |
| IV | 60 | 20x20 |