{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RH2921-4DA11","brand":"Siemens","brandSlug":"siemens","productSlug":"3RH2921-4DA11","canonicalUrl":"https://aoctrl.com/siemens/3RH2921-4DA11","factsUrl":"https://aoctrl.com/api/mcp/products/3RH2921-4DA11","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS auxiliary switch, 3RH2921-4DA11, snap-on mounting for contactor sizes S00, S0, S2, S3, ring terminal lug connection, 10 A AC-12, 6 kV surge voltage resistance.","salesMarkdown":"The Siemens SIRIUS 3RH2921-4DA11 is a first laterally mountable auxiliary switch designed for contactor relays and power contactors in sizes S00, S0, S2, and S3. It snaps onto the contactor without tools, adding auxiliary contact blocks to the side of the device. This is the standard way to add feedback or interlock contacts to a motor starter or contactor assembly on a DIN rail. Rated operational current at AC-12 reaches 10 A maximum, with a mechanical service life of 10 million operating cycles typical. It carries a mirror contact function per IEC 60947-4-1 when paired with a 3RT2 contactor, which is the safety-relevant feature: a mirror contact mechanically linked to the main contacts so a welded main contact is reflected in the auxiliary contact position. That matters for any safety circuit that needs to detect contactor weld. ## Mounting and connection — panel integration Snap-on mounting to the contactor side; the 10 mm width means it adds minimal DIN rail real estate. Height is 57.4 mm, depth 66 mm — check clearance against the enclosure door or gland plate if stacking multiple blocks. Connection is via ring terminal lug for the auxiliary and control circuits. That is a permanent, vibration-resistant termination — not a spring-cage or screw-clamp block. Plan for ring terminals with the correct stud size; no push-in wiring here. Front protection class is IP00 — no ingress protection on the front face. This is an inside-the-panel component only; not for washdown or outdoor use without an enclosure. The AC-15 operational current at 690 V is rated 1 A — this is the inductive load rating for solenoid or contactor coils at the higher voltage. The AC-12 rating (10 A) covers resistive loads like indicator lamps or heater contactors. The buyer selecting for a 24 VDC PLC input circuit should look at the contact reliability spec (17 V, 1 mA) rather than the thermal current — this switch is designed to switch dry signals reliably, not just power. No external surge suppression needed for the auxiliary circuit.","metaTitle":"Siemens 3RH2921-4DA11 SIRIUS Auxiliary Switch, snap-on","metaDescription":"Siemens SIRIUS 3RH2921-4DA11 auxiliary switch, snap-on for S00/S0/S2/S3 contactors. 10A AC-12, mirror contact per IEC 60947-4-1. Active production. Sourced to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Contactors"],"specifications":{"Depth":"66 mm","Width":"10 mm","Height":"57.4 mm","at 24 V":"6 A","at 48 V":"2 A","at 60 V":"2 A","at 110 V":"1 A","at 125 V":"0.9 A","at 220 V":"0.3 A","at 230 V":"6 A","at 250 V":"0.3 A","at 400 V":"3 A","During Storage":"-55 ... +80 °C","Leading Contact":"0","lifecycle_stage":"current","During Operation":"-25 ... +60 °C","Fastening Method":"snap-on mounting","Product Category":"Auxiliary switch","Lagging Switching":"0","Size Of Contactor":"S00, S0, S2, S3","Product Brand Name":"SIRIUS","Product Designation":"auxiliary switch","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","Design Of The Product":"first laterally mountable","Instantaneous Contact":"1","Substance Prohibitance (Date)":"10/01/2009","protection class IP on the front":"IP00","Surge Voltage Resistance Rated Value":"6 kV","Contact Reliability Of Auxiliary Contacts":"1 faulty switching per 100 million (17 V, 1 mA)","mirror contact according to IEC 60947-4-1":"Yes; with 3RT2","operational current at AC-15 at 690 V rated value":"1 A","Mechanical Service Life (Operating Cycles) Typical":"10 000 000","operational current of auxiliary contacts at AC-12 maximum":"10 A","Type Of Electrical Connection For Auxiliary And Control Circuit":"ring terminal lug connection","insulation voltage with degree of pollution 3 at AC rated value":"690 V","number of CO contacts of auxiliary contacts instantaneous contact":"0"}},"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=71636&mlfb=3RH2921-4DA11","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RH2921-4DA11/alternatives.json"},"ai":{"faq":[{"question":"What are the key dimensions for panel planning?","answer":"Width is 10 mm, height 57.4 mm, depth 66 mm. The 10 mm width is the critical dimension for DIN rail space when stacking multiple auxiliary blocks alongside the contactor."},{"question":"Will the 3RH2921-4DA11 drop into a panel specified around 6ES7136-6AB00-0CA1 without rewiring?","answer":"No. The 6ES7136-6AB00-0CA1 is a SIMATIC ET 200SP electronic module with a different form factor, bus connection, and wiring scheme (push-in terminals on a baseUnit). The 3RH2921-4DA11 is a side-mounted auxiliary switch for SIRIUS contactors with ring terminal lugs. The panel would need a complete rewiring and mechanical redesign."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RH2921-4DA11","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/3RH2921-4DA11 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}}