Siemens Automation System S7-400 - Manual (Page 33)

Installing the S7-400
2-17
Automation System S7-400 Hardware and Installation
A5E00850741-01
Connection to the Reference Point
For the connection to the reference point, use a cable lug for M4, a suitable spring
lock washer (for example, clamping washer to DIN 6796) and the cylinder-head
screw supplied.
Ungrounded assembly: Undo the fixing screws of the metallic connection on the
rack. Tilt the connection downwards. For the connection to the reference point, use
the original M4 x 8 supplied. Use the tilted metallic connection as a washer.
Grounded assembly: Leave the metallic connection on the rack. For the
connection to the reference point, use the original M4 x 8.
Reference point
Original screw with spring lock washer
M4 x 8
Connection
Spring lock washer
Original screw with spring lock washer
M4 x 8
Rack
Ungrounded configuration Grounded configuration
Metallic connection
Connection
Spring lock washer
Note
Do not use any cylinder-head screws that are longer than 6 mm for the connection
to the reference point. Otherwise, you may create an undesired connection bet-
ween the reference point and the rack profile behind it and therefore the connec-
tion for the chassis ground. For this reason as well, leave the metallic connection
on the rack and use it as a washer in an ungrounded configuration.