Siemens S5-100U User Manual page 490

S5-100U
C Active and Passive Faults in Automation
Equipment
Depending on the particular task for which the electronic automation equipment is used, both active
as well as passive faults can result in a dangerous situation. For example, in drive control, an
active fault is generally dangerous because it can result in an unauthorized startup of the drive. On
the other hand, a passive fault in a signalling function can result in a dangerous operating state not
being reported to the operator.
The differentiation of the possible faults and their classification into dangerous and non-dangerous
faults, depending on the particular task, is important for all safety considerations in respect to the
product supplied.
Warning
In all cases where a fault in automation equipment can result in severe personal injury or
substantial property damage, i.e., where a dangerous fault can occur, additional external
measures must be taken or equipment provided to ensure or force safe operating
conditions even in the event of a fault (e.g., by means of independent limit monitors,
mechanical interlocks, etc.).
Procedures for Maintenance and Repair
If you are carrying out measurement or testing work on an active unit, you must adhere to the rules
and regulations contained in the "VGB 4.0 Accident Prevention Regulations" of the German
employers liability assurance association ("Berufsgenossenschaften"). Pay particular attention to
paragraph 8, "Permissible exceptions when working on live parts."
Do not open the S5-100U. Do not attempt to repair an item of automation equipment. Such repairs
may be carried out only by Siemens service personnel or repair shops Siemens has authorized
to carry out such repairs.
EWA 4NEB 812 6120-02
Active and Passive Faults in Automation Equipment
C-1