{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RH1921-2HA22","brand":"Siemens","brandSlug":"siemens","productSlug":"3RH1921-2HA22","canonicalUrl":"https://aoctrl.com/siemens/3RH1921-2HA22","factsUrl":"https://aoctrl.com/api/mcp/products/3RH1921-2HA22","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RH1921-2HA22 auxiliary switch block, 2 NO + 2 NC, spring-loaded terminals, 10 A rated, for 3RT1 contactors, snap-on mounting.","salesMarkdown":"The Siemens SIRIUS 3RH1921-2HA22 is a 4-pole auxiliary switch block with 2 normally-open and 2 normally-closed instantaneous contacts, designed to snap onto 3RT1 contactors. It uses spring-loaded terminals for the auxiliary and control circuit connections, accepting 2x (0.5 to 1.5 mm²) with ferrule or 2x (0.5 to 2.5 mm²) without. Rated for a maximum of 10 A, with specific current ratings per voltage and duty: at 24 V it's rated 10 A (AC-12) and 6 A (DC-13); at 230 V it's 6 A; at 400 V it's 3 A. The AC-15 rating at 690 V is 1 A. These are the values that determine whether the block can handle the pilot duty or signal-level switching in your circuit — the 10 A headline applies only at low voltage and resistive loads. The successor 3RH2 series (e.g., 3RH2422-1AB00) is a different form factor — 90 mm wide versus 44 mm, and 73 mm deep versus 51 mm — so it will not drop into the same panel footprint without mechanical rework. The terminal type also changes from spring-loaded to screw-type on that successor. If the BOM calls for this exact 3RH1921-2HA22, the replacement is not a simple swap; it's a panel redesign. That's the low-level signal reliability — important if this block is switching PLC inputs or dry-contact signals where oxide film on the contacts can cause intermittent opens. Surge voltage resistance is rated at 6 kV, and the insulation voltage with pollution degree 3 is 690 V AC. That means the block is suitable for 400 V line-to-line control circuits in industrial environments where the pollution level is high (conductive dust or condensation). ## Panel integration The block is 44 mm wide, 51 mm deep, and 38 mm tall — it occupies one standard 45 mm-wide module position on the rail. It mounts directly onto the front of a 3RT1 contactor, not as a standalone device; the note \"with 3RT1\" means it's a clip-on accessory, not a separately wired block. Wiring: spring-loaded terminals accept 2x (0.5 to 1.5 mm²) with ferrule or 2x (0.5 to 2.5 mm²) without, or 2x (20 to 14 AWG). No screw torque to verify — the spring cage holds the conductor when the lever is released. Strip length per standard practice for this terminal type is 8 to 10 mm.","metaTitle":"Siemens 3RH1921-2HA22 SIRIUS Auxiliary Switch Block, 2 NO +","metaDescription":"Siemens SIRIUS 3RH1921-2HA22 auxiliary switch block, 2 NO + 2 NC contacts, 10 A rated, spring-loaded terminals, snap-on mounting. Phased-out; successor is SIRIUS 3RH2. Sourced to o","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)","Without Core End Processing":"2x (0.5 ... 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 ... 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":"spring-loaded 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=389253&mlfb=3RH1921-2HA22","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RH1921-2HA22/alternatives.json"},"ai":{"faq":[{"question":"What replaces the 3RH1921-2HA22?","answer":"The manufacturer's stated successor is the SIRIUS 3RH2 series. The 3RH2422-1AB00 is a peer in that series, but it is mechanically larger (90 mm wide vs 44 mm, 73 mm deep vs 51 mm) and uses screw terminals instead of spring-loaded. It will not fit the same panel footprint without rework."},{"question":"What are the key ratings for this auxiliary switch block?","answer":"Maximum 10 A. At 24 V: 10 A (AC-12) or 6 A (DC-13). At 230 V: 6 A. At 400 V: 3 A. AC-15 at 690 V: 1 A. Contact reliability: 1 fault per 100 million operations at 17 V, 1 mA. Mechanical life: 10 million cycles. Surge voltage: 6 kV. Insulation: 690 V AC, pollution degree 3."},{"question":"Does the 3RH1921-2HA22 work with any contactor or only specific ones?","answer":"It is designed for use with 3RT1 contactors, as indicated by the note \"with 3RT1.\" It clips onto the front of the contactor and is not a standalone DIN-rail device."},{"question":"What type of terminals does it use?","answer":"Spring-loaded terminals (cage clamp style) for both auxiliary and control circuits. Accepts 2x (0.5 to 1.5 mm²) with ferrule or 2x (0.5 to 2.5 mm²) without, or 2x (20 to 14 AWG)."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RH1921-2HA22","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/3RH1921-2HA22 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}}