{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3SK1121-1AB40-1AA0","brand":"Siemens","brandSlug":"siemens","productSlug":"3SK1121-1AB40-1AA0","canonicalUrl":"https://aoctrl.com/siemens/3SK1121-1AB40-1AA0","factsUrl":"https://aoctrl.com/api/mcp/products/3SK1121-1AB40-1AA0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens 3SK1121-1AB40-1AA0 safety relay, SIL 3 / PL e, 24 V rated, 12 A total at 40 °C, screw terminals, 22.5 mm wide, snap-on mounting.","salesMarkdown":"## Safety relay for guarding circuits — SIL 3 / PL e The Siemens 3SK1121-1AB40-1AA0 is a safety relay rated for use in safety-related circuits up to SIL 3 per IEC 61508 and IEC 62061, and PL e per ISO 13849-1, with a safe failure fraction of 99 %. The 22.5 mm wide housing mounts on a DIN rail via screw and snap-on fastening, and accepts screw-type terminals for solid (1x 20–14 AWG, 2x 18–16 AWG) and stranded (1x 20–16 AWG, 2x 20–16 AWG) conductors. Total current through the safety relay is limited to 12 A at 40 °C ambient, derating to 6 A at 60 °C. The maximum operating frequency is 360 cycles per hour. Power loss peaks at 2 W. Mounting position is any, but observe the derating curve above 40 °C. ## Switching capacity and response times Contact ratings: 1 A at 24 V DC, 1.5 A at 115 V AC, and 1.5 A at 230 V AC. The typical response time is 30 ms, with a maximum of 50 ms; the DC-side maximum is 110 ms. The sensor input minimum pulse duration is 75 ms. Shock resistance is rated at 10 g / 11 ms. ## EMC and environmental ratings EMC emitted interference complies with IEC 60947-5-1, Class A. Overvoltage category is 3, degree of pollution is 3. Insulation voltage is rated at 300 V. The design supports cascading of multiple units.","metaTitle":"Siemens 3SK1121-1AB40-1AA0 Safety Relay, SIL 3 / PL e, 22.5","metaDescription":"Siemens 3SK1121-1AB40-1AA0 safety relay, SIL 3 (IEC 61508) / PL e (ISO 13849-1). 24 V rated, 12 A total at 40 °C. Screw terminals, 22.5 mm wide. Active production. Quoted to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"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":"50 ms","Typical":"30 ms","at 24 V":"1 A","Stranded":"1x (20 ... 16), 2x (20 ... 16)","at 115 V":"1.5 A","at 230 V":"1.5 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","Shock Resistance":"10g / 11 ms","Mounting Position":"any (observe derating)","Degree Of Pollution":"3","Overvoltage Category":"3","according to IEC 61508":"3","according to IEC 62061":"3","power loss [W] maximum":"2 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","total current at 40 °C maximum":"12 A","total current at 60 °C maximum":"6 A","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","Safety-Related Delayed Switching":"0","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":"3","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","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","For Signaling Function Instantaneous Contact":"1","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":"2.5E-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","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","Backslide Delay Time After Opening Of The Safety Circuits Typical":"40 ms","thermal current of the switching element with contacts at 40 °C maximum":"5 A","thermal current of the switching element with contacts at 60 °C maximum":"2 A","design of the fuse link for short circuit protection of the NC contacts of the relay outputs required":"Diazed or Neozed fuses, operating class gL/gG: 6 A or MCB type A: 2 A or MCB type B: 2 A or MCB type C: 1 A","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/3SK1121-1AB40-1AA0/alternatives.json"},"ai":{"faq":[{"question":"What safety integrity levels does 3SK1121-1AB40-1AA0 meet?","answer":"It meets 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 total current capacity of 3SK1121-1AB40-1AA0?","answer":"Total current is 12 A maximum at 40 °C, derating to 6 A at 60 °C."},{"question":"Where can I buy 3SK1121-1AB40-1AA0 and get current pricing?","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/3SK1121-1AB40-1AA0","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/3SK1121-1AB40-1AA0 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}}