Siemens SIMATIC NET PROFIBUS manual Electrical Safety, Power Supply Voltage, DC Power Supply

Installing LAN Cables

C.2 Electrical Safety

The signal levels on electric PROFIBUS cables are low voltage. Correctly installed and operated PROFIBUS LAN cables do not have dangerous electrical voltages.

Remember, however, the following rules when installing the power supply for all components (nodes, bus components, etc.) that you want to connect to a PROFIBUS cable.

Power Supply Voltage

Between components operated on mains power supply and the PROFIBUS interface, the requirements of safe electrical isolation from the power supply complying with DIN VDE 0160 and DIN IEC 950/VDE 0805/EN 60950/ UL 1950/ CSA 22.2 No. 950 must be met. /7/

24 V DC Power Supply

24 V DC power supplies for components must meet the requirements of low voltage with safe electrical isolation from the network complying with DIN VDE 0160 and DIN IEC 950/ VDE 0805/EN 60950/ UL 1950/ CSA 22.2 No. 950 must be met. /7/

Protection from External Electrical Influences

Cable or wire breaks must not lead to undefined statuses in the plant or system.

PROFIBUS Networks SIMATIC NET	C-3
6GK1970-5CA20-0AA1 Release 2 05/2000