Description
2.6 Protection system
3VA molded case circuit breakers with IEC certificate
Manual, 03/2019, A5E03603177010-03
79
Neutral conductor protection (N)
The ID letter for neutral conductor protection is "N".
The neutral conductor protection system protects the neutral conductor against overloads
and short circuits.
The letters I
N
refer to the current setting value; the associated setting time is identical to t
r
.
A neutral conductor with full cross sectional area (distributed neutral conductor of the same
size as the phases) is normally protected by the phase protection system and does not
require separate protection.
Neutral conductor protection
Neutral conductor protection must be implemented in accordance with the standards valid in
the country of installation. Possible reasons for implementing neutral conductor overload
protection are:
● The neutral conductor has a smaller cross section than the phase conductors.
● Harmonic levels in the installation are expected to be higher than normal.
● A large number of loads, or predominantly single-phase loads, will be connected.
Neutral conductor protection and 3VA1 molded case circuit breakers
The following 3VA1 molded case circuit breakers have neutral conductor protection:
● All 4-pole versions of 3VA11, 3VA12, 3VA13, 3VA14 (TM210, TM220, TM240)
All of these molded case circuit breakers are available in versions without or with
100% neutral conductor protection. A version with 50% neutral conductor protection is
available in addition for rated operational currents greater than 100 A.
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