Overcurrent Protection - Siemens SINAMICS S120 Equipment Manual

8.3.4

Overcurrent protection

Cables on both the primary and the secondary side of the 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
● Cable bundling (e.g. laying in a common 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".
The 24 V DC connection of the
● Line Modules
● Motor Modules
● DC link components
Booksize Power Units
Equipment Manual, (GH2), 07/2007, 6SL3097-2AC00-0BP5
conditions
Cabinet Design and EMC Booksize
8.3 24 V DC supply voltage
437