The electrician's system: univers N - Hager

Earthing conductor connection univers N
for enclosure housing and carrier rails
TT-System (Principle Diagram)
L1
L2
L3
N
In case of fault:
mit R B ≈ 3 Ω
R A ≈ 20 Ω
I F is small and doesn't bring the fuse to trip within 0.2s to 0.5s
RB
RA
IF
Tripping condition:
R A · I a ≤ U L
with
R A = Earthing resistance of chassis in Ω
I a = Current in A, which makes the protection device disconnect
U L = maximum continuous allowable touch voltage:
U L ~ = 50 V, U L – = 120 V from DIN VDE 0100 part 200
Therefore the earth fault switch with breaking sensitivity up to
max 500mA is fitted. With a "small" residual current, it is sufficient
to use the 10mm 2 copper wire cable (included) and connect
the carrier rails with the metal rail connector.
TN-System (Principle Diagram)
L1
In case of fault:
PEN
L2
L3
N
Protective earthing:
Earthing:
PE
IF
IF
I F –> ∞
with R –> 0
I F –> ∞
RB
RA
Nullung
RA
Erdung
Tripping condition:
Z S · I a ≤ U 0
with
Z S = Surge impedance of the wire loop in Ω
I a = Current in A, which causes the automatic tripping
U 0 = Nominal Voltage against earthed currents in V
It is necessary to lay out the earth protected current accordingly
with the continuous current. Therefore the 10mm 2 and 16mm 2
copper wire cable must be used to earth the carrier rails for a
nominal current of 250A. This gives a earth protected current
width of 25mm 2 . For 400A the width for earth protection is
50mm 2 , and 630A is 75mm 2 (values according to DIN VDE 0660
part 500). Corresponding wires are offered in the univers range
276