Requirements Of Sensors And Actuators For Fail-Safe Modules - Siemens SIMATIC S7-1500 System Manual

Even when a fault occurs, the permissible potential difference between the supply of the
interface module (bus voltage) and the load voltage must not be exceeded.
An external direct electrical connection is one way to meet this requirement. This also
prevents potential differences from causing voltage additions at the individual voltage
sources, which could cause the fault voltage U
Requirements for power supplies in the event of voltage interruption
Note
To ensure adherence to IEC 61131-2, only use power packs/power supply units (24 V DC)
with a mains buffering time of at least 20 ms.
Please also note the requirements of the applicable standards regarding mains buffering
time.
You can find information on the power supply components on the Internet.
8.2.2

Requirements of sensors and actuators for fail-safe modules

General requirements for sensors and actuators
Note the following important warning regarding safety-related use of sensors and actuators:
Note that instrumentation with sensors and actuators bears a considerable safety
responsibility. Also bear in mind that sensors and actuators generally do not have a service
life of 20 years as defined in IEC 61508:2010 without considerable loss of safety.
The probability of hazardous faults and the rate of hazardous faults of safety functions must
comply with an SIL-defined high limit. A listing of values achieved by F-modules in the
technical specifications of the F-modules is available under "Fail-safe performance
characteristics".
To achieve the respective safety class, suitably qualified sensors and actuators are
necessary.
SIMATIC Drive Controller
System Manual, 11/2023, A5E46600094-AD
WARNING
WARNING
8.2 Additional rules and regulations for operation
to be exceeded.
m
Connecting
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