2.6.3 Equipotential bonding

The equipotential bonding system is used to equalize the earth potential at different locations of the plant so that no current flows over the shielding of the PROFIBUS-cable.

1. Use copper cables or galvanized ground strips for the equipotential bonding in the system and between system components.
   
   
2. Connect the equipotential bonding to the grounding terminal or bar with a large surface area.
   
   
   
   
3. Connect all PROFIBUS device shield and ground connections (if available) to the equipotential bonding system.
   
   
   
   
4. Connect the mounting surface (for example cabinet panel or mounting rails) with the equipotential bonding system.
   
   
5. Connect the PROFIBUS equipotential bonding system to the building equipotential bonding system as often as possible.
   
   
   
   
6. If parts are painted, remove the paint from the connecting point before the connection.
   
   
   
   
7. Protect the connecting point against corrosion after mounting, e.g. with zinc or varnish paint.
   
   
8. Protect the equipotential bonding against corrosion. One option consists of painting the contact points.
   
   
9. Use secure screw or terminal connections for all ground and bonding connections. Use locking washers to avoid the connections becoming loose because of vibration or movement.
   
   
10. Use wire-end ferrules or cable lugs for flexible equipotential bonding cables. The cable ends should never be tinned (no longer allowed)!
    
    
11. Route the equipotential bonding as close as possible to the PROFIBUS cable
    
    
    
    
12. Connect the individual parts of metal cable trays to each other. Use special bonding links or jumpers for this purpose. Ensure that bonding links are made from the same material as the cable trays. Cable tray manufacturers will be able to supply appropriate bonding links.
    
    
    
    
13. Connect cable trays made out of metal as often as possible with the equipotential bonding system.
    
    
    
    
14. Use flexible bonding links for expansion joints. Bonding links are available from cable manufacturers.
    
    
15. For PROFIBUS connections between different buildings or parts of buildings, you must route an equipotential bonding parallel to the PROFIBUS cable.
    Maintain the following minimum cross sections according to IEC 60364-5-54:
    - Copper           6 mm²
    - Aluminium     16mm²
    - Steel              50 mm²