Overcurrent Protection - Siemens SINAMICS Series Equipment Manual

7.3.4

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 power supply of booksize
• Line Modules
• Motor Modules
• Braking Modules
• Capacitor Modules
is implemented in the components by means of a 24 V busbar for 24 V DC and reference
potential. The current carrying capacity of these bars is 20 A. The power supply is connected
via a 24 V terminal adapter. MCBs are recommended to protect the cables from overcurrent.
These overcurrent protection devices also protect the 24 V busbars.
When an external power supply is used (e.g. SITOP), the earth potential must be connected
to the protective conductor system (PELV).
The Control Supply Module is integrated in the drive line-up and supplies the 24 V directly to
the 24 V busbars. A 24 V terminal adapter can be used to supply additional components.
The earth potential for the Control Supply Module is connected to the protective conductor
system inside the device.
Equipment Manuel for Booksize Power Modules
Manual, (GH2), Edition 06.2005, 6SL3097-2AC00-0BP2
conditions
Cabinet Configuration and EMC Booksize
7.3 24 V DC supply voltage
7-11