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Overview
1.8 Terms for fail-safe operation
1.8
Terms for fail-safe operation
This section defines terms relating to fail-safe operation with a fail-safe HMI device.
You can find additional information on the topic of "Safety" in the following document:
"SIMATIC Safety - Configuring and Programming" programming and operating manual
(http://support.automation.siemens.com/WW/view/en/54110126)
Fail-safe automation system, F system
A fail-safe automation system is required in a plant with high safety requirements. An F-
system is characterized by the following features:
● Safety-related shutdown response of the system after the triggering of a stop or
emergency stop via a safety-related operator control.
● The confirmation of machine movements entailing danger via an enabling mechanism.
In combination with the fail-safe Mobile Panel, a hard-wired F-system is used: The safety-
related operator controls are wired to a safety relay. If one of the safety-related operator
controls is activated, the safety relay triggers the safe state or confirms a machine movement
entailing danger in the F-system via the enabing button.
Safe operating state
If an unexpected event occurs during plant operation that poses a risk to persons or
equipment, the plant must respond with a defined safety shutdown. Protection of personnel
against physical injury can only be ensured if intervention in manufacturing processes, for
example during retrofitting or troubleshooting, is safe and secure.
Based on the risk analysis, the safety shutdown and therefore the shutdown response of the
plant must therefore be configured to ensure that the plant or plant area can be switched to a
safe operating state in the event of a risk.
In addition to the qualitative risk analysis required, the machine operator also has an
obligation to make a quantitative assessment of potential hazards. On this basis, the
operator must then establish what risks could arise during plant or plant area operation and
whether the relevant safety functions are sufficiently effective for the hazard in question.
The safe operating state is assigned to the fail-safe controller by a safety program. The plant
constructor is responsible for the required configuration which should be described in the
plant documentation.
Fail-safe operation
In a hardwired F-system, you operate the plant or a plant section in fail-safe mode. In fail-
safe mode, the safety-related operator controls emergency stop/stop button and enabling
buttons are active. Fail-safe mode runs via a fixed connection with a safety relay.
22
Operating Instructions, 08/2017, A5E39831415-AA
TP1000F Mobile RO
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