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Description
2.3 Protection system
2.3.5.5
Neutral protection N
The neutral conductor can be protected against overload and short-circuit with the
electronic trip unit. The neutral conductor protection consists of a separate overload
protection and a common short-circuit protection for the three phases and the neutral
conductor.
The overload protection has the setting I
the thermal memory correspond to the settings of the overload protection of the three
phases. For four-pole circuit breakers, the setting I
by the maximum rated current I
For the short-circuit protection of the N-conductor, the settings of the short-time-
delayed short-circuit protection ST and the instantaneous short-circuit protection INST
are adopted.
Note
For a 3-pole circuit breaker, an external current sensor (N-CT) is required to protect the
neutral conductor, see Chapter External current sensor for neutral pole (Page 349).
For 4-pole circuit breakers, the internal current sensor for the neutral conductor is pre-
installed at the factory.
Characteristic
56
. The delay, the overload characteristic, and
rN
of the overload protection is limited
rN
of the circuit breaker.
n max
Equipment Manual, 02/2023, 92310000002-06
3WA1 air circuit breaker
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