{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RH1921-1FA11","brand":"Siemens","brandSlug":"siemens","productSlug":"3RH1921-1FA11","canonicalUrl":"https://aoctrl.com/siemens/3RH1921-1FA11","factsUrl":"https://aoctrl.com/api/mcp/products/3RH1921-1FA11","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RH1921-1FA11 attachable auxiliary switch block, 2-pole 1 NO + 1 NC, screw-type terminals, snap-on mounting, rated 10 A maximum.","salesMarkdown":"The Siemens 3RH1921-1FA11 is a SIRIUS attachable auxiliary switch block, 2-pole with 1 normally open and 1 normally closed contact, designed for snap-on mounting onto contactors in the 3RT1 series. It carries a maximum continuous current rating of 10 A, with specific switching capacities defined across a range of control voltages — 6 A at 24 V AC/DC, 6 A at 125 V, 6 A at 230 V, and 3 A at 400 V, among others — making it suitable for signaling and interlocking circuits in motor control centers and industrial panels. ## Contact Ratings and Application Context The 10 A maximum rating applies across the board, but the real selection parameter is the voltage-specific switching capacity. At 24 V it switches 6 A; at 110 V it drops to 1 A; at 220 V it handles 0.3 A. This derating curve means the block is best applied in low-voltage control circuits (24–125 V) where it delivers its full 6 A capability. The AC-15 rated value at 690 V is 1 A, confirming its use in auxiliary contactor and relay circuits rather than main power paths. Mechanical service life is rated at 10,000,000 switching cycles typical, with contact reliability specified as 1 faulty switching per 100 million operations at 17 V, 1 mA — a strong indicator for high-cycle applications like conveyor interlocking or safety gate monitoring. Snap-on mounting directly onto 3RT1 contactors — no tools required for attachment. Dimensions are compact: 44 mm wide, 51 mm deep, 38 mm high. The screw-type terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) with core end processing, or 2x (20–16) and 2x (18–14) AWG. Front protection class is IP20, suitable for enclosed panel installation. Insulation voltage is rated at 690 V AC with degree of pollution 3, and surge voltage resistance is 6 kV — adequate for industrial environments with moderate transient exposure.","metaTitle":"Siemens 3RH1921-1FA11 SIRIUS Auxiliary Switch Block, 1NO+1NC","metaDescription":"Siemens 3RH1921-1FA11 SIRIUS attachable auxiliary switch block, 2-pole 1NO+1NC, rated 10A max. Phased-out; successor is 3RH2 series. Sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Contactors"],"specifications":{"Note":"with 3RT1","Depth":"51 mm","Width":"44 mm","Height":"38 mm","Maximum":"10 A","at 24 V":"6 A","at 60 V":"2 A","at 110 V":"1 A","at 125 V":"6 A","at 220 V":"0.3 A","at 230 V":"6 A","at 250 V":"6 A","at 400 V":"3 A","During Storage":"-55 ... +80 °C","lifecycle_stage":"current","During Operation":"-25 ... +60 °C","Fastening Method":"snap-on mounting","Product Brand Name":"SIRIUS","Suitability For Use":"Contactor relay and power contactor","at 24 V rated value":"10 A","at 60 V rated value":"4.7 A","at 110 V rated value":"3 A","at 220 V rated value":"1.2 A","at 440 V rated value":"0.5 A","at 600 V rated value":"0.26 A","Instantaneous Contact":"1","With Core End Processing":"2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²)","at AC-15 at 690 V rated value":"1 A","protection class IP on the front":"IP20","Surge Voltage Resistance Rated Value":"6 kV","at AWG cables for auxiliary contacts":"2x (20 ... 16), 2x (18 ... 14)","Contact Reliability Of Auxiliary Contacts":"1 faulty switching per 100 million (17 V, 1 mA)","Mechanical Service Life (Switching Cycles) Typical":"10 000 000","Type Of Electrical Connection For Auxiliary And Control Circuit":"screw-type terminals","insulation voltage with degree of pollution 3 at AC rated value":"690 V"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":null,"sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=15133&mlfb=3RH1921-1FA11","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RH1921-1FA11/alternatives.json"},"ai":{"faq":[{"question":"What is the successor to 3RH1921-1FA11?","answer":"The official successor is the SIRIUS 3RH2 series. For a direct functional replacement, the 3RH2122-1WB40 is a close peer with 2 NO + 2 NC contacts, similar voltage ratings, and screw-type terminals, though it has a larger footprint (73 mm depth vs 51 mm)."},{"question":"What does 'with 3RT1' mean in the description?","answer":"It means this auxiliary switch block is designed to snap onto Siemens 3RT1 series contactors. It is not a standalone device — it mounts directly onto the contactor to add auxiliary signaling contacts."},{"question":"What are the key contact ratings for 3RH1921-1FA11?","answer":"Maximum continuous current is 10 A. Voltage-specific ratings include 6 A at 24 V, 6 A at 125 V, 6 A at 230 V, 3 A at 400 V, and 1 A at 110 V. At 690 V AC-15 duty it is rated 1 A."},{"question":"Where can I buy 3RH1921-1FA11?","answer":"This phased-out part is sourced through independent distribution channels. Availability and current pricing are confirmed at quote time against an RFQ — submit a request for a firm quote on your required quantity."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RH1921-1FA11","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/3RH1921-1FA11 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}}