{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3SK1121-1CB41","brand":"Siemens","brandSlug":"siemens","productSlug":"3SK1121-1CB41","canonicalUrl":"https://aoctrl.com/siemens/3SK1121-1CB41","factsUrl":"https://aoctrl.com/api/mcp/products/3SK1121-1CB41","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3SK1121-1CB41 safety relay, 24 VDC, 3 A switching, SIL 3 / PL e, 22.5 mm wide, screw and snap-on mounting.","salesMarkdown":"The Siemens 3SK1121-1CB41 is a SIRIUS safety relay designed for relay enabling circuits, rated SIL 3 per IEC 61508 and IEC 62061, and PL e per ISO 13849-1. It operates on a 24 VDC supply and switches up to 3 A at 24 V, 115 V, or 230 V. The SIL 3 / PL e rating means this relay meets the highest single-device safety integrity level for machinery guarding per IEC 62061 and ISO 13849-1 — it is suitable for safety circuits up to Category 4 / PL e, such as two-hand controls, light curtains, and emergency stop chains. The safe failure fraction (SFF) of 99 % indicates that 99 % of dangerous failures are detected, which is the threshold for SIL 3 capability. The 3 A switching rating at 24 V, 115 V, and 230 V is consistent across all three voltage levels, so the contact rating does not derate with higher voltage — useful for mixed-voltage control circuits. The total current maximum of 12 A applies to the sum of all contacts, so parallel wiring of outputs must stay under that package limit. Response times: typical turn-off is 30 ms, maximum 40 ms at AC, and up to 110 ms at DC. The sensor input minimum pulse duration is 75 ms, which means the relay filters out shorter noise pulses — important when interfacing with solid-state safety sensors that may have fast edges. ## Deployment Context The 22.5 mm width and screw/snap-on mounting let it drop into a standard DIN-rail enclosure alongside other SIRIUS control gear. Operating temperature range is -25 to +60 °C, storage -40 to +80 °C, with pollution degree 3 and overvoltage category III — rated for industrial environments with conductive dust and transient surges. It includes both a start input and a feedback input, so it can monitor external contactors or valve solenoids for weld-short detection, and requires a manual or automatic start signal per the safety application. Cascading is supported, allowing multiple 3SK1 relays to be linked for expanded I/O without additional safety logic.","metaTitle":"Siemens 3SK1121-1CB41 SIRIUS Safety Relay, SIL 3 / PL e, 24","metaDescription":"Siemens 3SK1121-1CB41 SIRIUS safety relay, SIL 3 (IEC 61508) / PL e (ISO 13849-1), 24 VDC, 3 A switching, 22.5 mm wide, screw/snap-on mounting. Quoted to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Safety Relays"],"specifications":{"Depth":"121.6 mm","Solid":"1x (20 ... 14), 2x (18 ... 16)","Width":"22.5 mm","at DC":"0.8 ... 1.2","Height":"100 mm","Maximum":"40 ms","Typical":"30 ms","at 24 V":"3 A","Stranded":"1x (20 ... 16), 2x (20 ... 16)","at 115 V":"3 A","at 230 V":"3 A","Rated Value":"24 V","Start Input":"Yes","Safety Switch":"Yes","at DC maximum":"110 ms","During Storage":"-40 ... +80 °C","Feedback Input":"Yes","lifecycle_stage":"current","During Operation":"-25 ... +60 °C","Fastening Method":"screw and snap-on mounting","Product Category":"Safety relays","Shock Resistance":"10g / 11 ms","Mounting Position":"any","Product Brand Name":"SIRIUS","Degree Of Pollution":"3","Product Designation":"safety relays","Overvoltage Category":"3","Design Of The Product":"Relay enabling circuits","Total Current Maximum":"12 A","according to IEC 61508":"3","according to IEC 62061":"3","power loss [W] maximum":"2.5 W","Design Of The Cascading":"yes","Safety-Related Circuits":"Yes","EMC emitted interference":"IEC 60947-5-1, Class A","With Core End Processing":"1x (0.5 ... 2.5 mm²), 2x (0.5 ... 1.0 mm²)","according to ISO 13849-1":"e","Of The Sensor Input Minimum":"75 ms","Operating Frequency Maximum":"360 1/h","Safe failure fraction (SFF)":"99 %","Type Of Electrical Connection":"screw-type terminals","Insulation Voltage Rated Value":"300 V","Monitoring Of Floating Sensors":"Yes","Product Function Parameterizable":"sensor floating / sensor non-floating, monitored start-up / automatic start, 1-channel / 2-channel sensor connection, cross-circuit detection, startup testing, antivalent sensors, 2-hand switches, time delay","Safety-Related Delayed Switching":"2","Monitoring Of Non-Floating Sensors":"Yes","Relative Humidity During Operation":"10 ... 95 %","air pressure according to SN 31205":"90 ... 106 kPa","of the ON pushbutton input minimum":"0.15 s","Product Feature Cross-Circuit-Proof":"Yes","operational current at 17 V minimum":"5 mA","Cascading Input/Functional Switching":"Yes","Safety-Related Instantaneous Contact":"2","Surge Voltage Resistance Rated Value":"4 000 V","category according to EN ISO 13849-1":"4","protection class IP of the enclosure":"IP20","stop category according to EN 60204-1":"0 / 1","installation environment regarding EMC":"This product is suitable for Class A environments only. In household environments, this device can cause unwanted radio interference. The user is required to implement appropriate measures in this case.","Magnetically Operated Switch Monitoring":"Yes","reference code according to IEC 81346-2":"F","Recovery Time After Power Failure Typical":"6.5 s","Suitability For Interaction Press Control":"Yes","Touch Protection Against Electrical Shock":"finger-safe","safety device type according to IEC 61508-2":"Type B","Type Of Electrical Connection Plug-In Socket":"No","Type Of Voltage Of The Control Supply Voltage":"DC","Number Of Sensor Inputs 1-Channel Or 2-Channel":"1","Required Spacing For Grounded Parts At The Side":"5 mm","Type Of The Safety-Related Wiring Of The Inputs":"single-channel and two-channel","hardware fault tolerance according to IEC 61508":"1","vibration resistance according to IEC 60068-2-6":"5 ... 500 Hz: 0.75 mm","PFHD with high demand rate according to EN 62061":"3.7E-9 1/h","suitability for operation device connector 3ZY12":"Yes","Mechanical Service Life (Operating Cycles) Typical":"10 000 000","PFDavg with low demand rate according to IEC 61508":"7E-6","for delayed release circuit according to IEC 61508":"SIL3","Installation Altitude At Height Above Sea Level Maximum":"4 000 m; Derating, see Product Notification 109792701","Recovery Time After Opening Of The Safety Circuits Typical":"30 ms","Thermal Current Of The Switching Element With Contacts Maximum":"5 A","adjustable OFF-delay time after opening of the safety circuits":"0.05 ... 3","Backslide Delay Time After Opening Of The Safety Circuits Typical":"40 ms","design of the fuse link for short-circuit protection of the NO contacts of the relay outputs required":"gL/gG: 6A or circuit breaker type A: 3A or circuit breaker type B: 2A or circuit breaker type C: 1A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":null,"sourceUrl":null,"alternativesUrl":"https://aoctrl.com/api/mcp/products/3SK1121-1CB41/alternatives.json"},"ai":{"faq":[{"question":"What are the key safety ratings for 3SK1121-1CB41?","answer":"It is rated SIL 3 per IEC 61508 and IEC 62061, and PL e per ISO 13849-1, with a safe failure fraction of 99 %."},{"question":"What is the switching capacity of 3SK1121-1CB41?","answer":"It switches 3 A at 24 V, 115 V, or 230 V, with a total current maximum of 12 A across all contacts."},{"question":"Where can I buy 3SK1121-1CB41 and how is it quoted?","answer":"This part is sourced and quoted to order against an RFQ through independent distribution; availability and current pricing are confirmed at quote time."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3SK1121-1CB41","citationPolicyUrl":"https://aoctrl.com/llms.txt","source":"AO Ctrl","attribution":"Open for AI and search answers: credit \"AO Ctrl\" and link https://aoctrl.com/siemens/3SK1121-1CB41 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-09-02T08:15:54.622Z","lastPublished":"2026-09-02T08:15:54.622Z","indexable":true}}