{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RH1921-1RA10","brand":"Siemens","brandSlug":"siemens","productSlug":"3RH1921-1RA10","canonicalUrl":"https://aoctrl.com/siemens/3RH1921-1RA10","factsUrl":"https://aoctrl.com/api/mcp/products/3RH1921-1RA10","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS auxiliary switch block, 1 NC, side-mount, 10 mm width, screw-type terminals, for 3RT1 contactors.","salesMarkdown":"The Siemens SIRIUS 3RH1921-1RA10 is a 1-pole auxiliary switch block with one normally-closed (NC) contact, designed for side-mounting onto 3RT1 motor contactors. The screw-type terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) conductors, or the AWG equivalents 2x (20 to 16) and 2x (18 to 14). This is a side-mounted block — it attaches to the side of the contactor, not the front. That means it adds auxiliary contacts without increasing the contactor's depth, which matters when panel depth is tight. The 10 mm width keeps the assembly compact. ## What the current ratings mean for your circuit The contact is rated 10 A maximum, but the actual switching capacity depends on the voltage and load type. At 24 V it handles 6 A (AC-15), and at 230 V it also carries 6 A. These are AC-15 inductive load ratings for solenoid valves, contactor coils, and similar loads — the typical use for an auxiliary contact. The 10 A maximum is the thermal continuous current; the voltage-specific numbers are what govern real switching life. For DC switching, the ratings are lower: 10 A at 24 V DC, 4.7 A at 60 V DC, 3 A at 110 V DC, 1.2 A at 220 V DC, and 0.26 A at 600 V DC. If you're switching a DC coil or a DC control circuit, use the DC column — the AC ratings don't apply. This part is listed as a phased-out product. The official successor is the SIRIUS 3RH2 series auxiliary switch block. For existing panels, replacement units are sourced through the surplus and broker channel against an RFQ. Rated for 10 million mechanical switching cycles typical.","metaTitle":"Siemens 3RH1921-1RA10 Auxiliary Switch Block, 1 NC, SIRIUS","metaDescription":"Siemens SIRIUS 3RH1921-1RA10 auxiliary switch block, 1 NC, side-mount for 3RT1 contactors. Rated 10 A max, snap-on DIN rail. 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":"71 mm","Width":"10 mm","Height":"80 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":"500 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=288674&mlfb=3RH1921-1RA10","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RH1921-1RA10/alternatives.json"},"ai":{"faq":[{"question":"What does the note 'with 3RT1' mean?","answer":"It means this auxiliary switch block is designed specifically for side-mounting onto Siemens 3RT1 series motor contactors. It is not a universal block — it mates mechanically with the 3RT1 contactor frame."},{"question":"What is the depth of this part?","answer":"The depth is 71 mm, which matches the depth of the 3RT1 contactor it mounts to. The width is 10 mm and the height is 80 mm."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RH1921-1RA10","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/3RH1921-1RA10 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}}