Accessories
4.4 Plug-in and draw-out technology
3VA molded case circuit breakers with UL and IEC certification
Manual, 01/2019, L1V30435333-01
221
Plug-in and draw-out technology
4.4.1
In most applications, 3VA UL molded case circuit breakers are fixed-mounted in
switchboards or distribution panels. The breaker is normally secured by mounting screws
directly to the mounting plate or other suitable supports inside the panel. The cables or
busbars of the main circuits are connected directly to the 3VA UL molded case circuit
breaker with various terminals or connectors. The molded case circuit breaker thus has a
fixed and rigid connection to the control panel.
For certain applications, such as for cyclic inspections or service, it must be possible to
replace the 3VA UL molded case circuit breakers quickly. To meet this requirement, the
molded case circuit breakers can be retrofitted for plug-in and draw-out technology.
The main differences between plug-in units and draw-out units are convenience of operation
and the potential for functional expansion.
Plug-in technology is the less expensive and more space-saving of the two solutions. Here,
the molded case circuit breaker in inserted into the corresponding socket and equipped with
plug-in contacts that establish a force- and form-fitted connection with the mating contacts in
the plug-in socket – the tulip contacts. In this case, the device is plugged in and withdrawn
manually.
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