Installing the S7-400

2-13

AutomationSystem S7-400 Hardwareand Installation
A5E00850741-01
Mounting Screws

Youhave a choice of the following types of screw for securing a rack:

Screw Type Explanation
M6 cylinder-head screw to
ISO 1207/ISO 1580 (DIN 84/DIN 85)
Choose the screw length according to your
assembly.
Y
o
u
a
l
s
o
n
e
e
d
“
6
4
”
w
a
s
h
e
r
s
t
o
I
S
7
0
9
2
M6 hex. screw to ISO 4017 (DIN 4017)
Y
ou a
l
so nee
d
“
6
.
4
”
was
h
ers
t
o
I
S
7
0
9
2
(DIN 433).
Step 3: Connecting the Rack to the Chassis Ground

Connect the rack to the chassis ground. A threaded bolt is provided for this

purpose on the bottom left of the rack.

Minimum cross-section of the conductor to the chassis ground: 10 mm2.

If the S7-400 is mounted on a mobile rack, you must provide a flexible conductor to

the chassis ground.

Note

Always ensure that there is a low-impedance connection to the chassis ground

(see the figure below). Youachieve this with the shortest possible, low-resistance

conductor with a large surface to establish large-area contact.

M6 threaded bolt
Terminal
Plain washer
Contact washer
M6 nut
Tochassis ground