ABB Advant AC500 - Number of User Data, Bus Cycle Time and Data Security; Replacement of Modules on the CS31 System Bus

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V2 AC500 Hardware 1-39 System data AC500 / Issued: 05.2007
Case b:
Multiple switch-gear cabinets: If potential differences can occur between the switch-gear cabinets, the
capacitive earthing method is chosen in order to avoid circulating currents on the cable shields.
CS31
SHIELD
BUS 2 BUS 1
slave
CS31 system bus
Earthing bar of cabinet 1
CS31-
SHIELD
BUS 2 BUS 1
Slave
120
Ohms
CS31-Systembus
CS31-
BUS 1
BUS 2
SHIELD
Slave
PE
Earthing bar
of cabinet 2
Cabinet earthing
Cabinet earthing
Cabinet 1
Cabinet 2
PE
PE
1
2
3
4
120
Ohms
COM1
PE
CS31 bus master
e.g. PM581
direct
earthing
with clip
on cabinet
steel plate
capacitive earthing with 0.1 uF
X-type capacitor directly on the
cabinet’s steel plate
Figure: Earthing concept with several switch-gear cabinets: direct earthing of cable shields when cables
enter the first switch-gear cabinet (containing the master), and capacitive earthing at the modules
Everywhere is valid: The total length of the earthing connections between the shield of the Terminal
Base and the earthing bar must be as short as possible (max. 25 cm). The conductor cross section must
be at least 2.5 mm².
VDE 0160 requires, that the shield must be earthed directly at least once per system.
Number of user data, bus cycle time and data security
See the relevant chapters in the user handbook.
Replacement of modules on the CS31 system bus