ABB AC500 PLC Hardware Manual page 1285

Fig. 235: Bus line: Correct
Fig. 236: Bus line: Wrong
2.6.4.8.4 Earthing
In order to avoid disturbance, the cable shields must be earthed directly.
Case a:
Multiple switch-gear cabinets: If it can be guaranteed that no potential differences can occur
between the switch-gear cabinets by means of current-carrying metal connections (earthing
bars, steel constructions etc.), the direct earthing is chosen.
Cabinet 1
Fig. 237: Direct earthing
Case b:
2019/04/17
PE
COM1
1
2
3
4
120
Ohms
CS31 bus master
e.g. PM581
current-carrying connection
3ADR010121, 13, en_US
System Assembly, Construction and Connection
AC500 (Standard) > Connection and Wiring
direct earthing of shields
when entering the cabinet
CS31
slave
Cabinet 2
current-carrying connectio
CS31
slave
n
1285