Siemens Simatic S7-300, Руководство по аппаратному обеспечению и установке, Страница: 198 / 242

Appendix
S7-300 Programmable Controller Hardware and Installation
11-10
A5E00105492-01
Keys for sample 1
The numbers in the following list refer to the numbers in the figure above.
Table 11-6 Keys for sample 1
No
.
Description Explanation
1 Ground straps If no large-surface metal-to-metal connections are available,
you must either interconnect inactive metal parts (e.g. cabinet
doors or mounting plates) or bond them to chassis ground using
ground straps. Use short ground straps with a large surface.
2 Supporting bars Interconnect the supporting bars on a large area to the cabinet
walls (metal-to-metal connection).
3 Mounting the
profile rail The mounting bar and module rack must be interconnected with
large-area metal-to-metal connections.
4 Signal cables Connect the shielding of signal cables on a large area of the
protective conductor/additional shielding busbar and fasten
them with cable clamps.
5 Cable clamp The cable clamp must cover a large area of the shielding braid
and ensure good contact.
6 Shielding busbar Interconnect the shielding busbar on a large surface with the
supporting bars (metal-to-metal connection). The cable
shielding is terminated on the busbar.
7 Protective
conductor busbar Interconnect the protective conductor busbar on a large surface
with the supporting bars (metal-to-metal connection).
Interconnect the protective conductor busbar and the protective
ground system, using a separate cable (minimum cross-section
10 mm
2
).
8 Cable to the
protective ground
system
(equipotential
ground) Interconnect the cable on a large area with the protective
ground system (equipotential ground).
Example 2: EMC compatible wall mounting
When operating your S7 in a low-noise environment that conform with permissible
ambient conditions (see Appendix Ambient conditions), you can also mount your
S7 in frames or to the wall.
Interference coupling must be diverted to large metal surfaces. Therefore, always
mount standard profile/shielding/protective conductor rails on metal parts of the
construction. Steel sheet panels reference potential surfaces have been found
especially suitable for wall-mounting.
Provide a shielding busbar for connecting your cable shielding. This shielding
busbar can also be used as protective conductor busbar.
Note the following points on frame-/wall-mounting:
•
When mounting on varnished or anodized metal parts, use special contact
washers or remove the insulating layers.