Safety-rated bundle for SIL 3 / PL e applications
The Siemens 3SK1912-3SB40 is a SIRIUS Advanced Bundle — a pre-assembled safety engineering package rated to SIL 3 (IEC 61508), SIL CL 3 (IEC 62061), and PL e (ISO 13849-1) with Category 4 structure (EN ISO 13849-1). That means it meets the highest standard for guarding hazardous machinery: a single fault in any component cannot cause loss of the safety function, and the system detects the fault at the next demand or automatically. The hardware fault tolerance is HFT = 1 (IEC 61508-2), and the device type is Type A, so its failure modes are well-defined and predictable.
What's in the box — BOM verification
This bundle ships as a complete safety sub-system. The package includes a safety relay, expansion module, motor starter, pushbutton, enclosure parts, holders, base connectors, safety switches, and a connecting cable.
IP20 finger-safe enclosure
The enclosure carries IP20 protection, which means it is finger-safe against accidental contact with live parts but not sealed against moisture or dust ingress. Mount inside a cabinet or panel with a minimum IP54 rating if the environment has washdown or airborne particulates. The screw-type and spring-loaded terminal options (both listed) let you choose between traditional ring-lug wiring and tool-less spring-cage termination — useful when panel builders prefer one method over the other.
Active lifecycle — no end-of-life concern
The 3SK1912-3SB40 carries an Active lifecycle status from Siemens. No phase-out or last-time-buy notice is on record.
Altitude derating and installation limits
Maximum installation altitude is 4 000 m above sea level, with derating required above that per Siemens Product Notification 109792701. The bundle includes both start input and feedback input terminals.