{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RH1921-1PA22","brand":"Siemens","brandSlug":"siemens","productSlug":"3RH1921-1PA22","canonicalUrl":"https://aoctrl.com/siemens/3RH1921-1PA22","factsUrl":"https://aoctrl.com/api/mcp/products/3RH1921-1PA22","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RH1921-1PA22 auxiliary switch block, 2 NO + 2 NC contacts per EN 50005, 4-pole, screw-type terminals, snap-on mounting for Size S0...S3 contactors, 10 A maximum, IP20 front.","salesMarkdown":"The Siemens SIRIUS 3RH1921-1PA22 is a 4-pole auxiliary switch block with a 2 NO + 2 NC contact arrangement wired to EN 50005. It snaps onto Size S0 through S3 contactors — specifically the 3RT1 power contactor family noted in the spec — adding auxiliary signalling or interlocking without extra DIN-rail space. The screw-type terminals accept 2x (0.5...1.5 mm²) or 2x (0.75...2.5 mm²) with core-end processing, and 2x (20...16) or 2x (18...14) AWG for auxiliary wiring. ## Contact ratings — what they mean at the panel The block carries a maximum thermal current of 10 A, but the real-world switching capacity depends on the voltage you are breaking. At 24 V it switches 6 A (AC-15/DC-13 typical), at 125 V it handles 6 A, at 230 V it still manages 6 A, but at 400 V it drops to 3 A, and at 600 V it is down to 0.26 A. The AC-15 rating at 690 V is 1 A. That means for a 24 VDC PLC input circuit you have full 6 A headroom; for a 400 V control transformer interlock you need to stay under 3 A per contact. ## Lifecycle reality — this is a phased-out part The manufacturer lists the 3RH1921-1PA22 as a phased-out product. The official successor is the SIRIUS 3RH2 series auxiliary contactor/switch block. Snap-on mounting onto the contactor front — no DIN rail required for the block itself, though the host contactor typically rails. The block measures 44 mm wide by 38 mm high by 51 mm deep. The insulation voltage is rated 690 V at pollution degree 3, with a 6 kV surge voltage resistance — adequate for 400 VAC motor control panels with proper clearance.","metaTitle":"Siemens 3RH1921-1PA22 Auxiliary Switch Block, 2NO+2NC, 10A","metaDescription":"Siemens SIRIUS 3RH1921-1PA22 auxiliary switch block, 2 NO + 2 NC, 10 A max, screw terminals, snap-on for 3RT1 contactors. Phased out; successor is 3RH2 series.","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":"2","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=518288&mlfb=3RH1921-1PA22","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RH1921-1PA22/alternatives.json"},"ai":{"faq":[{"question":"Is 3RH1921-1PA22 obsolete?","answer":"Yes, the 3RH1921-1PA22 is a phased-out product. The manufacturer's official successor is the SIRIUS 3RH2 series auxiliary contactor/switch block."},{"question":"What is the replacement for 3RH1921-1PA22?","answer":"The official replacement is the SIRIUS 3RH2 series — for example, the 3RH2122-1AC60 offers the same 2 NO + 2 NC contact arrangement with screw terminals and snap-on mounting, with a 30-million-cycle mechanical life vs the 10-million-cycle life of the original."},{"question":"Can 3RH1921-1PA22 be used with 3RT1 contactors?","answer":"Yes, the spec explicitly notes this block is designed for use with 3RT1 contactors, snapping onto Size S0 through S3 frames."},{"question":"What are the specifications of 3RH1921-1PA22?","answer":"It is a 4-pole auxiliary switch block with 2 NO + 2 NC contacts, rated 10 A maximum thermal current. Contact ratings vary by voltage: 6 A at 24 V, 6 A at 125 V, 6 A at 230 V, 3 A at 400 V, 0.26 A at 600 V. It uses screw-type terminals, snap-on mounting, and measures 44 x 38 x 51 mm. Mechanical life is 10 million switching cycles typical."},{"question":"Where can I buy 3RH1921-1PA22?","answer":"This phased-out part is sourced through independent distribution channels. Submit an RFQ for current availability and pricing — stock and lead time are confirmed at quote time, not guaranteed on a listing."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RH1921-1PA22","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/3RH1921-1PA22 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}}