Product description
3.3 Configuration
3VL IEC molded case circuit breakers
22 System Manual, 11/2013, 110 0110 - 02 DS 03
Functional principle
Mechanical design
All 3VL molded case circuit breakers have a trip-free mechanism that ensures the trip
process is not prevented even if the operating mechanism is blocked or manually held in the
"ON" position.
The contacts are opened and closed by a toggle lever positioned in the center. This is
attached to the front side on all molded case circuit breakers.
All 3VL molded case circuit breakers are "joint trip units". This means all contacts open or
close simultaneously when the molded case circuit breaker toggle lever is moved from "OFF"
to "ON" or from "ON" to "OFF", or when the tripping mechanism is activated by an
overcurrent or with the help of the auxiliary trips (shunt release or undervoltage release).
The 3VL molded case circuit breakers are designed on the principle of magnetic repulsion of
the contacts. The contacts open before the expected peak-value of the short-circuit current is
reached. Magnetic repulsion of the contacts very considerably reduces the thermal load I
2
t
as well as the mechanical load resulting from the impulse short-circuit current I
P
of the
system components that occur during a short-circuit.
You can find more information in the chapter Use in motor protection (Page 64).
Subdivision according to power ranges
VL160X molded case circuit breakers
The most important components of the VL160X molded case circuit breakers are the three
current paths with the incoming and outgoing terminals. The fixed and movable contacts are
arranged in such a way as to guarantee magnetic repulsion of the contacts. In conjunction
with the arcing chambers, a dynamic impedance is generated that causes current limitation.
This reduces the damaging effects of excessively high values I
2
t and I
p
.
The overcurrent release is a factory-installed thermal-magnetic device. It is equipped with
fixed or adjustable overload releases and a fixed short-circuit release in each pole.
To the right and left of the centrally positioned toggle lever of every SENTRON VL molded
case circuit breaker is a double-insulated accessory compartment for installing auxiliary
switches or alarm switches as well as shunt releases and undervoltage releases.
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