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D-90
Protective circuits
Additional informations
Designing the PE protective
conductor
The protective conductor must be sufficiently sized and securely installed in the
switchboard to accept the thermal and electrodynamic constraints of the fault
current.
It must be connected to the exposed conductive parts of the switchboard.
It must be access ble to enable connections both in the factory and on site.
Optimised calculation method
Use the calculation equation indicated in standard IEC 60439-1.
S
PE
: cross-sectional area of the PE in mm²
I
: value of the phase-to-earth fault current = 60 % of the value of the phase-to-
phase fault current (IEC 60439-1 §8.2.4.2)
t
: time the fault current flows in seconds
k
: coefficient that depends on the type of metal, k = 143 for a copper conductor
with PVC insulation.
Simplified method (based on the equation above)
Use the table below to determine the size of the PE conductor as a function of
device short-circuit current Isc.
b
b
b
b
DD381471
Size of PE conductor
All Schneider Electric devices
Isc
y
40 kA
1 bar, 25 x 5 mm
Linergy 630
Isc
y
65 kA
1 bar, 50 x 5 mm
Linergy 630
Isc > 65 kA
1 bar, 50 x 5 mm
Linergy 800
Schneider Electric prefabricated solution
For Schneider Electric devices up to Isc values of 85 kA, see page B-72.
Practical information