Appendix
A.3 Lightning and surge voltage protection
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05
A-21
A.3.3
Rules for the transition point between lightning protection zones 0 <-> 1
Rules for transition point 0 <-> 1 (lightning protection equipotential bonding)
The following measures are suitable for lightning protection equipotential bonding at the
transition between lightning protection zones 0 <-> 1:
•
Use grounded, spiraled, current-conducting metal straps or metal braiding as a cable
shield at both ends, for example, NYCY or A2Y(K)Y.
•
Install cables in one of the following media:
–
in continuous metal pipes that are grounded at both ends, or
–
in continuously armored concrete ducts or
–
on closed metal cable trays grounded at both ends.
–
use fiber-optic cables instead of metal conductors.
Additional Measures
If you cannot take measures as described above, you must install a high-voltage protection
for your system between the 0 <-> 1 transition points with a lightning conductor. The table
below contains the components you can use for high-voltage protection of your plant.
Table A-8
Highvoltage protection of cables with the help of surge protection equipment
Consec.
no.
Cables for ...
... ... equip transition point 0 <-> 1 with:
Order number
3-phase TN-C system
1 x
DEHNbloc/3 lightning conductor
Phase L1/L2/L3 to PEN
900 110*
5SD7 031
1 x
DEHNbloc/3 lightning conductor
Phase L1/L2/L3 to PE
900 110*
5SD7 031
3-phase TN-S system
1 x
DEHNbloc/1 lightning conductor
N to PE
900 111*
5SD7 032
1 x
DEHNbloc/3 lightning conductor
Phase L1/L2/L3 to N
900 110*
5SD7 031
3-phase TT system
1 x
DEHNgap B/n
N-PE lightning conductor N to
PE
900 130*
AC TN-S system
2 x
DEHNbloc/1 lightning conductor
Phase L1 + N to PE
900 111*
5SD7 032
AC TN-C system
1 x
DEHNbloc/1 lightning conductor
Phase L to PEN
900 111*
5SD7 032
1 x
DEHNbloc/1 lightning conductor
Phase to N
900 111*
5SD7 032
1
AC TT system
1 x
DEHNgap B/n
N-PE lightning conductor N to
PE
900 130*
