{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RH1921-1HK22","brand":"Siemens","brandSlug":"siemens","productSlug":"3RH1921-1HK22","canonicalUrl":"https://aoctrl.com/siemens/3RH1921-1HK22","factsUrl":"https://aoctrl.com/api/mcp/products/3RH1921-1HK22","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RH1921-1HK22 attachable contact block, 4-pole 2NO+1NC+1NC, 10 A maximum, screw-type terminals, snap-on mounting for 3RT1 contactors.","salesMarkdown":"The Siemens SIRIUS 3RH1921-1HK22 is an attachable contact block designed specifically for 3RT1 contactors, providing four auxiliary poles in a 2NO+1NC+1NC configuration — the second NC contact is a lagging (after-position) pole. This is a screw-type terminal block, not a cage-clamp variant, so expect to terminate with a #1 Pozidriv bit. Rated for a maximum of 10 A, the contact ratings vary significantly by voltage and duty: at 24 V it switches 6 A (AC-15/DC-13), at 110 V it handles 1 A, at 230 V it carries 6 A, and at 400 V it drops to 3 A. The DC switching curve is steeper — at 24 V DC it's rated 10 A, at 60 V DC it's 4.7 A, at 220 V DC it's 1.2 A, and at 600 V DC it's 0.26 A. That means for a 24 V DC control circuit this block comfortably handles pilot-duty loads, but at higher DC voltages you need to respect the derating or risk welded contacts. The block snaps onto the front of a 3RT1 contactor — no tools, no DIN rail — and occupies the auxiliary contact bay. Dimensions are compact: 44 mm wide, 38 mm tall, 51 mm deep, fitting within the contactor envelope. ## Contact reliability and service life For low-level signal switching (17 V, 1 mA), the contact reliability specification is one faulty switching per 100 million operations, meaning this block can be trusted for PLC input sensing or safety circuit feedback without stutter. The insulation system is rated for 690 V AC at pollution degree 3, with a surge voltage withstand of 6 kV. That puts it in the standard industrial control panel class — fine for 400/480 V motor circuits with adequate clearance. Snap-on mounting to the 3RT1 contactor front. The screw terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) with core end processing, or 2x (20 to 16) and 2x (18 to 14) AWG. The lagging NC contact (the second NC pole, marked as after-position) is mechanically delayed relative to the main contactor operation — useful for interlocking or status feedback where you need the auxiliary to change state after the main contacts have opened or closed.","metaTitle":"Siemens 3RH1921-1HK22 SIRIUS Contact Block, 4-Pole 2NO+1NC+1","metaDescription":"Siemens SIRIUS 3RH1921-1HK22 attachable contact block, 4-pole (2NO+1NC+1NC), 10 A max, screw terminals, snap-on for 3RT1 contactors. Active lifecycle. Quoted to order.","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","Lagging Switching":"1","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=66386&mlfb=3RH1921-1HK22","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RH1921-1HK22/alternatives.json"},"ai":{"faq":[{"question":"What is the 3RH1921-1HK22 contact block used for?","answer":"It is an attachable auxiliary contact block for Siemens 3RT1 contactors, providing 4 poles (2NO+1NC+1NC lagging) for control circuit switching, status feedback, or interlocking."},{"question":"How does 3RH1921-1HK22 compare to 3RH2122-1WB40?","answer":"The 3RH2122-1WB40 is a standalone coupling relay (size S00) with its own coil, not an attachable block. It shares the same contact ratings and screw terminal type but is a different form factor (73 mm deep vs 51 mm) and mounts on DIN rail independently, not onto a 3RT1 contactor. They are not drop-in interchangeable — the 3RH1921-1HK22 requires a 3RT1 contactor as a host."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RH1921-1HK22","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/3RH1921-1HK22 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}}