Page 242 - 35_DS702_E_2014_Lightning_Protection_Guide

Nominal values Tripping value
F1 of the NH fuse calculated in case
L
PE I n I t min of impulse currents
2
N A A s (8/20 µs) kA
2
1 2
35 3 030 14.7
F1 ≤ 25 A gL /gG electronic 63 9 000 25.4
DEHNrail DR MOD 255 device 100 21 200 38.9
125 36 000 50.7
160 64 000 67.6
3 4
200 104 000 86.2
F1 250 185 000 115.0
L
PE Table 8.1.7.2 Impulse current carrying capability of NH fuses when
N subjected to impulse currents (8/20 µs)
F2
electronic
F1 > 25 A device kA 8 4.0 kV
1 2
7 3.5
F2 ≤ 25 A I 6 impulse current 3.0 U S
DEHNrail DR MOD 255 5 2.5
4 voltage of the fuse 2.0
3 1.5
3 4
2 1.0
Figure 8.1.7.6 Example: DEHNrail 1 0.5
0 0
-200 0 200 400 600 800 1000 1200 1400 1600 1800
t µs

Nominal currents and design
Figure 8.1.7.8 Current and voltage of a melting 25 A NH fuse when
subjected to impulse currents (10/350 µs)
250 A/1 25 kA 75 kA
200 A/1 22 kA 70 kA
F 1 ... F 3 > maximum permissible
160 A/00 20 kA 50 kA backup fuse of the arrester
100 A/C00 9.5 kA 25 kA F 1 L1
F 2 L2
L3
F 3
63 A/C00 5.5 kA 20 kA N
35 A/C00 4 kA 15 kA F 4 F 5 F 6
F 4 ... F 6 ≤ maximum permissible U S
20 A/C00 1.7 kA 8 kA backup fuse of the arrester
0 10 20 30 40 50 60 70 80 90 100 U P
I (kA)
No melting Melting Explosion PE

Figure 8.1.7.7 Performance of NH fuses when subjected to impulse Figure 8.1.7.9 Use of a separate backup fuse for surge protective
currents (10/350 µs) devices

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