136 / 148
D-9
Earth-leakage protection
Connection of the rectangular-sensor secondary
circuit
Compact equipped with a Micrologic 7 A/P:
use the cable shipped with the rectangular sensor.
DB128388
Micrologic 7
4Z
3Z
2Z
1Z
5Z
I
Q
M1
M2
M3
U
M1
M2
T3
F2+
T2
T1/M3
T4/F1
L2 L3
L1 N
Neutral protection
three pole circuit breaker:
b
neutral protection is impossible with Micrologic A
v
with Micrologic E, P, an external neutral transformer
v
is necessary; the connection diagram is the same as
for residual earth-fault protection.
four pole circuit breaker:
b
Compact equipped with Micrologic A
v
the current transformer for external neutral is not
v
necessary.
Zone selective interlocking
Zone-selective interlocking is used to reduce the
electrodynamic forces exerted on the installation by shortening
the time required to clear faults, while maintaining time
discrimination between the various devices.
A pilot wire interconnects a number of circuit breakers
equipped with Micrologic A/E/P control units, as illustrated in
the diagram above.
The control unit detecting a fault sends a signal upstream and
checks for a signal arriving from downstream. If there is a
signal from downstream, the circuit breaker remains closed for
the full duration of its tripping delay. If there is no signal from
downstream, the circuit breaker opens immediately, regardless
of the tripping-delay setting.
Fault 1.
Only circuit breaker A detects the fault. Because it receives no
signal from downstream, it immediately opens in spite of its
tripping delay set to 0.3.
Fault 2.
Circuit breakers A and B detect the fault. Circuit breaker A
receives a signal from B and remains closed for the full duration
of its tripping delay set to 0.3. Circuit breaker B does not receive
a signal from downstream and opens immediately, in spite of its
tripping delay set to 0.2.
Wiring
Maximum impedance: 2.7
b
Ω
/ 300 m.
Capacity of connectors: 0.4 to 2.5 mm
b
2.
Wires: single or multicore.
b
Maximum lenght: 3000 m.
b
Limits to device interconnection:
b
the common ZSI - OUT (Z1) and the output ZSI - OUT (Z2)
v
can be connected to a maximum of 10 upstream device
a maximum of 100 downstream devices may be connected
v
to the common ZSI - IN (Z3) and to an input ZSI - IN CR ( Z4) or
GF (Z5).
Downstream
circuit break
Fault 1
Fault 2
Upstream
circuit break
tsd = 0.3
tsd = 0.2
A
B
Compact NS630b to 3200
Earth-fault and earth-leakage protection
Neutral protection
Zone selective interlocking
Electrical diagrams