Siemens Automation System S7-400 - Manual (Page 203)

Assembling and Installing Systems
A-35
Automation System S7-400 Hardware and Installation
A5E00850741-01
Shielding and Grounding under Industrial Conditions
If the monitor and programmable controller are operated under harsh industrial
conditions, you must observe the following:
On the side of the programmable controller:
• Connect the cable shields in the cabinet to the shielding busbar immediately
behind the cable inlet. The following points are important:
-- Strip the video cables without damaging the conductors.
-- Secure the outer braided shield with the largest possible area to the
shielding busbar of the programmable controller (for example, secure the
shielding with metal straps or cable clamps).
• Provide large-area contact between the shielding busbars and the frame or
cabinet wall.
• Connect the shielding busbar to the central grounding point of the cabinet.
On the side of the monitor:
• Isolate electronic ground and chassis ground from each other. Proceed as
follows:
-- Remove the jumper on the monitor to separate the two potentials.
-- Install a contact protection on the video sockets, because with isolated
grounding, a shock--hazard voltage of more than 40 V may develop in this
area.
!
Caution
There is a risk of personal injury.
Shock-hazard voltages may be present at the video sockets of the monitor.
Insulate the sockets.
• Connect the ground clamp of the monitor to the chassis ground.
• Connect the cable shields to the ground clamp of the monitor as follows:
Proceed as follows:
-- Strip the outer cable insulation of the video cables in the region of the ground
clamp of the monitor, without damaging the braided shield.
-- Secure the outer braided shield over a large area to the ground clamp of the
monitor.