Application Planning - Siemens SIRIUS 3RT Series System Manual

3RF34
3RF3410-.BD
3RF3410-.BD
3RF3410-.BD
3.6

Application planning

Notes about integration into load feeders
Thanks to their industrial connection system and type of design, SIRIUS solid-state switching
devices can be integrated into load feeders very easily.
However, particular attention must be paid to the circumstances of installation and ambient
conditions, as the performance of the solid-state switching devices is very much dependent
on these. Each design will impose certain restrictions which have to be taken into account.
Detailed information about minimum clearances can be found in the chapter titled Technical
data (Page 350), as well as in the product data sheets.
Despite the rugged nature of the power semiconductors used, solid-state switching devices
are sensitive to short circuits in the load feeder. Consequently, special precautions have to
be taken against irreparable damage as appropriate for the type of design.
The use of SITOR semiconductor fuses is generally recommended. These fuses provide
protection against irreparable damage in the event of a short circuit even in applications
where full use is being made of solid-state contactors.
Alternatively, in the case of a lower load, protection can also be provided by standard fuses
or miniature circuit breakers. This protection is achieved by overdimensioning the solid-state
switching devices accordingly. The technical data and the product data sheets contain
information about protection based on semiconductor fuses only as well as on the use of
SIRIUS devices with conventional protective devices.
Solid-state motor and reversing contactors can easily be combined with 3RV motor starter
protectors and circuit breakers, 3RB3 solid-state overload relays and 3RR2 current
monitoring relays from the SIRIUS modular system. As a result, fuseless and fused motor
feeders can be implemented easily and without taking up too much space.
Note
Running star-connected three-phase motors (particularly with power ratings < 1 kW) with
electromechanical contactors can cause significant electromagnetic interference. Such
interference, which exceeds permissible limit values, can cause solid-state switching devices
operating in the vicinity to malfunction.
In the case of high levels of electromagnetic interference we recommend equipping motors
up to 5.5 kW which are controlled using 3RT20 1 electromechanical contactors with EMC
surge suppressors. 3-phase RC interference suppression modules like the 3RT29 16-1PA1
(up to 400 V) provide the best filtering effect. Corresponding modules for the contactors are
listed in the product chapter titled "Contactors and contactor assemblies", under
"Accessories (Page 155)". Varistor interference suppression modules should not be used, as
they are not capable of filtering out rapid transients to the required extent.
SIRIUS Innovations
System Manual, 01/2011, A8E56203870002-03
Fuse
Max. size [A] Type
50 3NE4117
50 3NE8717-1
63 3NE8018-1
SIRIUS 3RF34 solid-state switching devices
3.6 Application planning
Current [kA]
65
65
65
Voltage [V]
480
480
480
339