{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3SK1121-2CB44","brand":"Siemens","brandSlug":"siemens","productSlug":"3SK1121-2CB44","canonicalUrl":"https://aoctrl.com/siemens/3SK1121-2CB44","factsUrl":"https://aoctrl.com/api/mcp/products/3SK1121-2CB44","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS safety relay, 3SK1121-2CB44, 24 VDC, SIL 3 / PL e, 3 A switching, 22.5 mm wide, screw and snap-on DIN rail mounting.","salesMarkdown":"The Siemens 3SK1121-2CB44 is a SIRIUS safety relay designed for enabling circuits in safety-related applications up to SIL 3 (IEC 61508, IEC 62061) and PL e (ISO 13849-1). It operates on a 24 VDC rated supply and switches up to 3 A at 24 V, 115 V, or 230 V. Safe failure fraction of 99 % — this relay meets the highest single-device integrity level for machinery safety functions. The 75 ms minimum sensor input pulse sets the shortest signal the relay will accept from a safety switch or light curtain; shorter pulses are filtered as noise. The 360 1/h maximum operating frequency limits mechanical cycling. At 22.5 mm wide, 100 mm high, and 121.6 mm deep, this relay fits a standard single-module DIN-rail slot. Screw terminals accept 1x or 2x solid/stranded conductors from 20 to 16 AWG; ferruled conductors from 0.5 to 1.0 mm². The relay includes start input, safety switch input, and feedback input for monitoring external contactors. Cascading is supported for multi-zone safety circuits. ## Electrical characteristics and approvals Total current maximum is 12 A across all contacts, with a maximum power loss of 2.5 W. The relay meets EMC emitted interference Class A per IEC 60947-5-1. Shock resistance is 10g / 11 ms. The 0.8... 1.2 at DC refers to the operating voltage tolerance range. Typical response time is 30 ms, maximum 40 ms; at DC maximum the release time is 110 ms.","metaTitle":"Siemens 3SK1121-2CB44 SIRIUS Safety Relay, SIL 3 / PL e, 24","metaDescription":"Siemens 3SK1121-2CB44 SIRIUS safety relay, 24 VDC, SIL 3 / PL e, 3 A switching at 24-230 V, 22.5 mm wide, screw/snap-on DIN rail. Current lifecycle stage. Sourced to order against","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Safety Relays"],"specifications":{"Depth":"121.6 mm","Solid":"1x (20 ... 16), 2x (20 ... 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 ... 1.0 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 %","Without Core End Processing":"1x (0.5 ... 1.5 mm²), 2x (0.5 ... 1.5 mm²)","Type Of Electrical Connection":"spring-loaded terminal (push-in)","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":"5 ... 300","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/3SK1121-2CB44/alternatives.json"},"ai":{"faq":[{"question":"What is the width and mounting of 3SK1121-2CB44?","answer":"The housing is 22.5 mm wide and mounts via screw or snap-on onto a DIN rail in any position."},{"question":"What wire sizes does 3SK1121-2CB44 accept?","answer":"Screw terminals accept 1x or 2x solid or stranded conductors from 20 to 16 AWG, and ferruled conductors from 0.5 to 1.0 mm²."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3SK1121-2CB44","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/3SK1121-2CB44 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}}