E

ARLY

S

TREAMER

E

MISSION

L

IGHTNING

C

ONDUCTORS

Protection area

The protection area Rp of a PREVECTRON
® 2 lightning conductoris calculated according to French Standard NF C 17-102, thus:Rp= √h (2D-h) + ∆L (2D + ∆L) The protection area depends on a number of factors: • Gain in triggering time ∆T of the chosen PREVECTRON
® 2(see Technical Guide: high-voltage laboratory PREVECTRON
® test results), which allows the ∆L value to be determined according to the formula ∆L (m) = V(m/_s) .∆T(_s);• D = 20, 45, or 60, depending on the protection levelrequired (I, II, or III) on a given site, according to the lightning risk assessment guide (NFC 17-102 appendix B);• the actual height of the lightning air terminal above thesurface to be protected: h (where h < 5m, see table below). Calculating the protection areausing Indelec's Protec 2001
© software

P

ROTECTION

R

ADII

h (m)234510

Level I : D = 20m

S 6.60 314763 79 79 S 4.50 274155 68 69

high protection

S 3.40 233546 58 59 TS 3.40 233546 58 59 TS 2.25 172534 42 44 h (m)234510 S 6.60 395878 97 99

Level II : D = 45m

S 4.50 345269 86 88

medium protection medium protectionstandard protectionhigh protection

S 3.40 304560 75 77 TS 3.40 304560 75 77 TS 2.25 233446 57 61 h (m)234510

Level III : D = 60m

S 6.60 436485 107 109

standard protection

S 4.50 385776 95 98 S 3.40 335067 84 87 TS 3.40 335067 84 87 TS 2.25 263952 65 69