Overcurrent Protection In The 24 V Solid-State Circuit - Siemens SINAMICS S120 Combi User Manual

Cabinet design and EMC
13.6 24 V DC supply
Using the 24 V connector
● A 24 V connector must be plugged onto the 24 V busbar between each S120 Combi,
● Insertion and withdrawal are only permissible in a de-energized state
● Only 5 withdrawal and insertion cycles are permissible
13.6.3

Overcurrent protection in the 24 V solid-state circuit

The cables on the primary and secondary sides of the 24 V supply unit must be protected
against overcurrent.
The protection on the primary side depends on the instructions of the equipment
manufacturer.
The protection on the secondary side depends on the actual conditions. Please note the
following:
● Loading from loads, possibly the demand factor against the operation of the machine
● Current carrying capacity of the conductors used and cables in normal and short-circuit
● Ambient temperature
● Cable bundling (laying cables in a common duct)
● Cable laying method to EN 60204-1
The overcurrent protection devices can be used according to EN 60204-1, Section 14.
Circuit breakers from the Siemens NSK catalog are recommended as overcurrent protection
devices on the primary side.
Miniature circuit breakers or SITOP select (order number 6EP1961-2BA00) are
recommended as overcurrent protection devices on the secondary side. The MCBs can be
selected according to Siemens catalog "BETA Modular Installation Devices - ET B1".
When selecting the miniature circuit breakers, the following standards must be observed:
● EN 61800-5-1
● EN 60204-1
● IEC 60364-5-52
● IEC 60287-1 to -3
● EN 60228
● UL 508C
244
expansion axis and DC-link component
conditions
SINAMICS S120 Combi
Manual, Edition 07/2012, 6SL3097-4AV00-0BP3