Protection Configurations
Typical protection configurations for various power systems are given below.
TN-S Network - Single-phase, 2+0
(T-connection)
F1
L
N
PE
F2
TN-C Network - Three-phase 3+0
(T-connection)
F1
L1
L2
L3
PEN
F2
TT Network - Three-phase 3+1
(T-connection)
F1
L1
L2
L3
N
F2
Remote signalization connection / Back-up fuse / Installation
Back-up fuse
F1 > 250 A gG → F2 = 250 A gG
F1 ≤ 250 A gG → F2 = not needed
F ≤ 100 A gG
Installation
F1
F2
a
a + b 0,5 m
b
min 16mm
L
N
PE
EBB
L1
L2
L3
PEN
EBB
L1
L2
L3
N
PE
EBB
2
TN-S Network - Three-phase, 4+0
(T-connection)
F1
L1
L2
L3
N
PE
F2
TT Network - Single-phase 1+1
(T-connection)
F1
L
N
F2
REPLACE SPD
O.K.
12
11
14
3Nm
L1
L2
L3
N
PE
EBB
L
N
PE
EBB
A.C.
250V / 0.5A
D.C.
250V / 0.1A
125V / 0.2A
75V / 0.5A