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

Cabinet design and EMC
12.6 24 V DC supply
Note
When using cables with a cross-section of 2.5 mm
the 24 V side if a type XLPE or EPR cable is used or a cable with a similar quality and with a
thermal stability of up to 90°C.
Using the 24 V connector
● A 24 V connector must be inserted on the 24 V busbar between the S120 Combi,
● Insertion and withdrawal are only permissible in a de-energized state
● Only 5 withdrawal and insertion cycles are permissible
12.6.3

Overcurrent protection in the 24 V solid-state circuit

Cables on both the primary and secondary side of the 24 V power supply unit must be
protected from overcurrent. Primary side protection must be implemented according to the
manufacturer's instructions.
Secondary side protection must be rated to deal with the actual conditions. In particular:
● Loading due to loads, possibly the simultaneity factor in response to machine operation
● Current carrying capacity of the conductors used and cables in normal and short-circuit
● Ambient temperature
● The bunching of the cables in a single duct
● Cable laying method to EN 60204-1
EN 60204-1, Section 14, can be used to determine the overcurrent protection devices.
Circuit breakers from the Siemens NSK catalog are recommended as overcurrent protection
devices on the primary side, and miniature circuit breakers or SITOP select 6EP1961-2BA00
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, you must take into account the following
standards:
EN 61800-5-1, EN 60204-1, IEC 60364-5-52, IEC 60287-1 to -3, EN 60228 and UL 508C.
250
expansion axes and DC link components
conditions
, no additional protection is required on
2
Manual, Edition 05.2010, 6SL3097-4AV00-0BP0
SINAMICS S120 Combi