Accessories
4.2 Internal accessories
3VA molded case circuit breakers with IEC certificate
204 Manual, 03/2019, A5E03603177010-03
Auxiliary releases allow remote electrical tripping of the circuit breaker. They can be used to
monitor control or main circuits in order to implement a protective system against accidental
restart following a power failure, for example.
Auxiliary releases therefore perform a main circuit monitoring function in addition to the main
circuit monitoring performed by the trip unit.
Auxiliary releases are extremely easy to install. No tools are required because these 21 mm
wide components are simply snapped into place in the accessory compartments to the left
and right of the handle. The accessories are connected by screw terminals for auxiliary
conductors with a cross-section of up to 1.5 mm
2
. The terminals are mounted on the front of
the unit for easy access.
The shunt trips are suitable for use in electrical interlocks. An attempt to switch on a circuit
breaker while the interlock voltage is applied to the shunt trip leads to a so-called "no-load
switching operation", i.e. the basic breaker always returns to the TRIP position and the main
contacts never close.
All auxiliary releases are reverse-polarity-protected.
Shunt trips of type STL can be fitted in the left-hand accessory compartment as an
alternative to an undervoltage release. The units are available with five rated voltages in the
following range:
● 24 to 600 V AC 50/60 Hz
● 12 to 250 V DC
They have a maximum power consumption of 58 VA which is significantly lower than the
power consumption of the flexible shunt trip versions.
Switches (permanent signal) or momentary push-buttons (minimum signal duration 40 ms)
may be used to control shunt trips.
Shunt trip left STL (EI) for electrical interlocks
Shunt trips of the type STL (EI) can be used to implement electrical interlocks between two
molded case circuit breakers. The interlocking auxiliary release prevents short-time contact
between the main contacts during a switch-on attempt.
Shunt trip STL (EI) is available with a rated voltage of 24 V DC.
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