{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RH2921-2DA02","brand":"Siemens","brandSlug":"siemens","productSlug":"3RH2921-2DA02","canonicalUrl":"https://aoctrl.com/siemens/3RH2921-2DA02","factsUrl":"https://aoctrl.com/api/mcp/products/3RH2921-2DA02","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS auxiliary switch block, 3RH2921-2DA02, 2 NC contacts, spring-loaded terminals, 10 A maximum, snap-on mounting for 3RT2 contactors and 3RH2 contactor relays.","salesMarkdown":"The Siemens 3RH2921-2DA02 is a lateral auxiliary switch block from the SIRIUS family, designed to snap onto the left side of 3RT2 contactors and 3RH2 contactor relays. It provides two normally-closed (NC) auxiliary contacts — one current path with two NC contacts — wired to terminals 51/52 and 61/62 on the left side, and 31/32 and 41/42 on the right side. The spring-loaded terminals accept 2x (0.5 to 1.5 mm²) with ferrule or 2x (0.5 to 2.5 mm²) solid, or 2x AWG 20 to 14, matching the standard panel wiring practice for control circuits. The maximum thermal current is 10 A, but the real-world switching capacity depends on voltage and load type. At AC-15 (inductive control-circuit duty) at 690 V, it's rated 1 A — that's the figure that governs fit for a 690 V control transformer or PLC output driving a contactor coil. At 24 V DC, the rated operational current is 6 A; at 60 V DC it drops to 2 A; at 110 V DC it's 1 A; and at 220 V DC it's 0.3 A. These DC ratings are the ones that matter when switching DC solenoids or brake coils — the AC thermal rating alone doesn't tell you whether the contacts will handle the DC arc. The insulation voltage is 690 V at pollution degree 3, and surge voltage resistance is 6 kV, so the block is suitable for 400 V and 480 V panels with proper clearance. Snap-on mounting to the contactor body — no DIN rail slot consumed, no extra panel space needed beyond the contactor's own footprint. The block is 10 mm wide, 64.8 mm high, and 66 mm deep, matching the contactor profile. ## Contact Reliability and Mechanical Life Mechanical service life is 10 million switching cycles typical. For a machine running at one cycle per second, that's about 115 days continuous; in practice, with intermittent use, it's years of service before mechanical wear-out.","metaTitle":"Siemens 3RH2921-2DA02 SIRIUS Auxiliary Switch, 2 NC, Spring-","metaDescription":"Siemens SIRIUS 3RH2921-2DA02 auxiliary switch block, 2 NC contacts, spring-loaded terminals, 10 A max, snap-on for 3RT2 contactors. Sourced to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Contactors"],"specifications":{"Note":"with 3RT2","Depth":"66 mm","Width":"10 mm","title":"3RH2921-2DA02","Height":"64.8 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","description":"auxiliary switch, lateral, 2 NC, on the left: 51/52, 61/62, on the right: 31/32, 41/42, current path: 1 NC, 1 NC, spring-loaded terminal, for contactors 3RT2 and contactor relays 3RH2","During Storage":"-55 ... +80 °C","Leading Contact":"0","lifecycle_stage":"current","During Operation":"-25 ... +60 °C","Fastening Method":"snap-on mounting","Lagging Switching":"0","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":"0","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":"$6.48","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/66810d3d065c371975805e394c848928.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=111736&mlfb=3RH2921-2DA02"},"ai":{"faq":[{"question":"What is the 'with 3RT2' note on this component?","answer":"The note indicates the auxiliary switch block is designed to mount on 3RT2 contactors and 3RH2 contactor relays. It snaps onto the left side of those devices."},{"question":"What is the depth of this auxiliary switch?","answer":"The depth is 66 mm, matching the profile of the 3RT2 contactor it mounts to."},{"question":"What are the key ratings for DC switching?","answer":"At 24 V DC it's rated 6 A, at 60 V DC 2 A, at 110 V DC 1 A, and at 220 V DC 0.3 A. These ratings govern fit for DC solenoid or brake coil circuits."},{"question":"What compliance documentation is available?","answer":"The part carries IP20 protection on the front, insulation voltage of 690 V at pollution degree 3, and surge voltage resistance of 6 kV. It is part of the Siemens SIRIUS range which typically meets IEC/EN standards for industrial control equipment."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RH2921-2DA02","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/3RH2921-2DA02 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-08-11T15:51:03.652Z","lastPublished":"2026-08-11T15:51:03.652Z","indexable":true}}