Siemens SIMATIC S7 F, Руководство пользователя

Страница: 165 / 354

Operation and Maintenance
Fail-Safe Systems
A5E00085588-03
6-5
Fiber-Optic Cables in S7 FH Systems
After a CPU of the S7-400 FH has been repaired, the fiber-optic cables must not
be disconnected from the CPUs at the same time. This must be prevented by
laying separate fiber-optic cables.
Preventative Maintenance (Proof Test)
The probability values specified in the section entitled "Safety" for the certified
components of the F-Systems ensure a proof test interval of 10 years for the
usual configurations. The proof test for complex electronic components usually
means they are replaced with unused ones. If there are special reasons why you
require an even longer proof test interval than 10 years, please contact your
Siemens advice center.
A shorter proof test interval is normally required for sensors and actuators.
Passivating Fail-Safe Output Modules Passive over the Long Term
If a fail-safe output module is passivated for an extended period (> 72h) and the
fault is not eliminated, it is possible for the module to be activated by a second
fault, thus putting the system in a dangerous state. Although the probability of such
hardware faults occurring is very slight, such unwanted activation of passivated F
output modules due to switching or organizational measures must be prevented.
One possibility is to switch off the power supply to the passivated module(s) for a
period of time (e.g. 72 hours).
In the case of systems for which there are product standards, the required
measures are standardized. In the case of all other systems, the expert accepting it
must approve the concept for the required measures put forward by the system
operator.
6.6 Uninstalling the S7 F/FH System
Uninstalling the software and disassembling and disposing of the hardware of an
F-System are carried out as normal.