Appendix
A.3 Lightning and surge voltage protection
S7-300, CPU 31xC and CPU 31x: Installation
A-26
Operating Instructions, Edition 08/2004, A5E00105492-05
A.3.5
Example: Surge protection circuit for networked S7-300 PLCs
The sample in the figure below shows you how install an effective surge protection for two
networked S7-300 PLCs:
CPU
SV
10 mm
2
PE
Cabinet 1
L1
L2
L3
N
PE
Lightning protection zone 0, field side
Lightning protection zone 1
Lightning protection zone 1
SM
MPI
CPU
SV
10 mm
2
PE
Cabinet 1
SM
MPI
Lightning protection zone 1
1
4
5
3
6
2
4
2
5
4
4
6
3
7
3