Note
*
)
SIL 2/3 per EN 61508 or PL d/e per EN ISO 13849-1
To achieve SIL 2/3 per IEC 61508 or PL d/e per EN ISO 13849-1, a fault exclusion such as a short-
circuit to a power cable or ground is required. This can be implemented, for example, within a
cabinet and by installing the connection cables in such a way that they are protected.
If this is not possible, the actuators must be wired via two safety-related outputs; see the right-
hand image. For this purpose, separate cables must be laid to actuators/contactors. In the
associated function element "F output," the output type "F output redundant" must be chosen.
Note
Protective circuit
A suitable protective circuit is needed for inductive loads. In this way, electromagnetic
interference can be suppressed and service life increased. You will nd further information in
Chapter "Requirements for actuators (Page 188)."
5.3.2.6 Connecting safety-related relay outputs
Relay outputs
Safety-related outputs of the 3RK3 central units are congured with two channels; those of the
expansion modules, with one channel.
To achieve SIL 2 / 3 per EN 61508 or PL d / e (Cat. 4) per EN ISO 13849‑1 of the expansion
modules, two relay outputs must be interconnected in a logic combination.
WARNING
Loss of the safety function.
Can Cause Serious Injury or Property Damage.
The relay contacts may weld if an overload occurs. The system cannot then shut down. To
prevent relay contact welding, the switched loads must be protected accordingly, see Chapter
"Technical data (Page 365)."
Note
Protection circuit
A suitable protective circuit is needed for inductive loads. In this way, electromagnetic
interference can be suppressed and service life increased. You will nd further information in
Chapter "Requirements for actuators (Page 188)."
Description of the hardware
5.3 Connecting / wiring
SIRIUS 3RK3 Modular Safety System
Equipment Manual, 07/2020, NEB926253002000/RS-AC/006 141
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