{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RH1921-2FJ22","brand":"Siemens","brandSlug":"siemens","productSlug":"3RH1921-2FJ22","canonicalUrl":"https://aoctrl.com/siemens/3RH1921-2FJ22","factsUrl":"https://aoctrl.com/api/mcp/products/3RH1921-2FJ22","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS auxiliary switch block, 3RH1921-2FJ22, 2 NO + 2 NC contacts, screw-type terminals, snap-on mounting for 3RT1 contactors, IP20 front, 690 V insulation.","salesMarkdown":"The Siemens 3RH1921-2FJ22 is a SIRIUS auxiliary switch block designed to snap onto 3RT1 contactor relays and power contactors (sizes S0 through S12). It provides 2 normally-open and 2 normally-closed auxiliary contacts — the NO contacts are encapsulated, the NC contacts are not — giving you feedback or interlock signals from the contactor without wiring a separate relay. The auxiliary contacts are rated for switching currents that vary with voltage: 0.3 A at 24 V and 60 V, 3 A at 110 V, and 1 A at 220 V. Mechanical life is 10 million switching cycles typical, which outlasts most contactors it will ride on. Snap-on mounting onto the contactor — no tools needed, no DIN rail required. The block is 44 mm wide, 51 mm deep, and 38 mm high, so it adds minimal footprint to the contactor assembly. Screw-type terminals accept 2x (0.5 to 2.5 mm²) solid or stranded without ferrules, or 2x (0.5 to 1.5 mm²) with ferrules. AWG equivalents are 2x (20 to 14). This part is flagged as a phased-out product. The official successor is the SIRIUS 3RH2 series. If your BOM is frozen on the 3RH1921-2FJ22, you can still source it through independent distribution — we quote and procure to order against an RFQ. For new designs, the 3RH2 series is the recommended drop-in replacement; verify the contact configuration and mounting compatibility with your 3RT1 contactor before committing the BOM line.","metaTitle":"Siemens 3RH1921-2FJ22 SIRIUS Auxiliary Switch Block, 2 NO 2","metaDescription":"Siemens 3RH1921-2FJ22 SIRIUS auxiliary switch block for 3RT1 contactors. 2 NO + 2 NC contacts, rated 690 V AC. Snap-on DIN rail mount. IP20 front. 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","at 24 V":"0.3 A","at 60 V":"0.3 A","at 110 V":"3 A","at 220 V":"1 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","Instantaneous Contact":"2","With Core End Processing":"2x (0.5 ... 1.5 mm²)","Without Core End Processing":"2x (0.5 ... 2.5 mm²)","protection class IP on the front":"IP20","Surge Voltage Resistance Rated Value":"6 kV","at AWG cables for auxiliary contacts":"2x (20 ... 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=476036&mlfb=3RH1921-2FJ22","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RH1921-2FJ22/alternatives.json"},"ai":{"faq":[{"question":"What is the 3RH1921-2FJ22 used for?","answer":"It is an auxiliary switch block that snaps onto Siemens 3RT1 contactor relays and power contactors (sizes S0 through S12) to add 2 NO and 2 NC auxiliary contacts for feedback or interlock signals."},{"question":"Where can I buy the 3RH1921-2FJ22?","answer":"We source and quote this part to order against an RFQ. Availability and current pricing are confirmed at quote time through our independent distribution network."},{"question":"What are the key ratings for the 3RH1921-2FJ22?","answer":"The auxiliary contacts are rated 3 A at 110 V, 1 A at 220 V, and 0.3 A at 24 V and 60 V. Insulation voltage is 690 V AC at pollution degree 3, with 6 kV surge voltage resistance. Mechanical life is 10 million switching cycles typical."},{"question":"Does the 3RH1921-2FJ22 fit a 3RT5056-8AP38-0PR0 contactor?","answer":"The 3RH1921-2FJ22 is designed for 3RT1 series contactors (sizes S0 through S12). The 3RT5056-8AP38-0PR0 is a different SIRIUS series; verify mechanical compatibility before substituting. The 3RH2 series is the official successor and should be checked for fit with your specific contactor frame."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RH1921-2FJ22","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/3RH1921-2FJ22 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}}