Connecting The Supply Voltage - Siemens SIMATIC S5 Manual

S5-95U, SINEC L2
Reasons for Removing the Connecting Plate
Connecting both ends of the shield of the SINEC L2 bus cable to protective ground provides good
noise suppression for high frequency ranges. It is the recommended method.
Note
Potential differences between the grounding points can cause an equalizing current to
flow on the shield connected on both sides that exceeds the capacity of the shield. In
that case, provide an equipotential bonding line.
Connecting only one end of the shield to protective ground should be the exception. It provides
damping only of low-frequency noises. Choose this method only if you cannot provide an
equipotential bonding line.
Remove the connecting plate between the shield clamps of segments 1 and 2. This opens the
connection to the protective ground conductor.
Warning
!
When the connecting plate between segment 1 and segment 2 is removed, electric
shock-hazard voltages 40 V can be present at the cable clamp of bus segment 1.
Make sure you provide appropriate contact protection.
2.3.2

Connecting the Supply Voltage

To connect the supply voltage (+24 V DC) to the screw-type terminal block, use a two-wire or
three-wire, shielded cable and prepare the shielding as follows (see Figure 2-6):
- Remove the insulation completely.
- Connect the shielding to the shield clamp of the repeater using the broadest connection
surface as possible.
- Connect the shielding at the power supply end to the protective ground conductor.
Bus
terminated
Bus segment
C A
Figure 2-6. Connecting the Supply Voltage to the L2 Repeater
EWA 4NEB 812 6112-02
Bus
terminated
Bus segment
B A B C C A B A B C
Installation Guidelines
PS 24V
M L1+ M L2+ PE
2-5