Page 223 - 35_DS702_E_2014_Lightning_Protection_Guide

L1 U 0 = 230 V a.c. L1 U 0 = 230 V a.c.
L2 Phase conductor to PE: L2 Phase conductor to neutral
L3 U c ≥ 1.1 x 230 V = 253 V a.c. L3 conductor:
N N U c ≥ 1.1 x 230 V = 253 V a.c.
PE Neutral conductor to PE: PE
U c ≥ 230 V a.c. Neutral conductor to PE:
3 x arrester with U c ≥ 253 V a.c. 1.1 U 0 U c ≥ 230 V a.c.
1 x arrester with U c ≥ 230 V a.c. 3 x arrester with U c ≥ 253 V a.c.
1.1 U 0 U 0 1 x arrester with U c ≥ 230 V a.c.
The values of U 0 between the
neutral conductor and PE The values of U 0 between the
already refer to the most U 0 neutral conductor and PE al-
unfavourable operating con- ready refer to the most un-
ditions. Therefore a tolerance favourable operating con-
of 10 % is not considered. ditions. Therefore a tolerance
R A of 10 % is not considered.
R A
U 0 = Phase-to-earth nominal a.c. voltage U 0 = Phase-to-earth nominal a.c. voltage

Figure 8.1.3.3a “4 – 0” circuit in a TN-S system Figure 8.1.3.3b “3+1” circuit in a TN-S system

external LPS lightning current arrester sub-distribution board surge arrester terminal devices
main distribution board

protection as per IEC 62305 (EN 62305)
F1 protection as per IEC 60364-4-443
L1
RCD L2
Wh L3
PEN SEB N
PE

F2 F3

MEB local EBB

Figure 8.1.3.4 SPDs used in a TN-C-S system

trip the RCD or cause mechanical damage. Figures 8.1.3.5 ning protection zone concept and the resulting lightning
to 8.1.3.11 illustrate the use of SPDs as part of the light- and surge protection measures for TN systems.

222 LIGHTNING PROTECTION GUIDE www.dehn-international.com