Siemens SIMATIC S5 Manual page 252

IP 265
F Active and Passive Faults in Automation
Systems
• Depending on the problem definition for an automation system, both active and passive faults
may be dangerous faults. In a drive control system, for example, active faults are normally
dangerous because they can result in unauthorized powering up of the drive. A passive fault, on
the other hand, might not be reported at all, and may be dangerous for just that very reason.
• This distinction, and the problem-dependent division of faults into those which are and those
which are not dangerous is of importance to all manner of safety considerations for a product.
Warning
Wherever faults occurring in an automation system can result in considerable damage
or even endanger humans, i.e. wherever such faults could be dangerous, additional
measures must be taken, or devices or methods implemented, to ensure safe
operation even in the event of a fault (e.g. the use of independent limit switches,
mechanical interlocks, etc.).
Maintenance procedures
If the IP 265 should require maintenance of any kind, please observe the stipulations and directives
in the accident prevention regulations VGB 4.0, particularly §8, "Permissible tolerances for active
components".
Under no circumstances may the IP 265 be opened.
Repairs on automation equipment may be carried out only by the Siemens Customer Service
Department or by repair shops authorized by Siemens.
EWA 4NEB 812 6130-02a
Active and Passive Faults in Automation Systems
F-1