Description
2.4 Selectivity
3VA molded case circuit breakers with IEC certificate
56
Manual, 03/2019, A5E03603177010-03
Depending on the molded case circuit breakers used, with a size/rated operational current
differential in a ratio of at least 1 : 2.5 and selection of suitable breaking capacity classes,
you can achieve selective tripping of the area of the installation directly affected by the fault
up to the maximum ultimate short-circuit breaking capacity.
You can find information on selectivity values for 3VA2 molded case circuit breakers on the
Internet under the link for 3VA documentation (
Electronic trip units and fast trip units
As a protective device, the molded case circuit breaker is required to clear electrical faults in
the system. For this purpose, 3VA2 circuit breakers are equipped with intelligent electronic
trip units which can be combined with metering functions.
The tripping characteristic of the electronic trip units can be finely and flexibly adjusted. In
the event of short circuits, a fast trip unit also responds according to the arc power from the
arc chute. This selective trip unit ensures that major short circuits are cleared more quickly,
while at the same time ensuring that medium short circuits are interrupted selectively.
