{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RH2921-2HA22-0KT0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RH2921-2HA22-0KT0","canonicalUrl":"https://aoctrl.com/siemens/3RH2921-2HA22-0KT0","factsUrl":"https://aoctrl.com/api/mcp/products/3RH2921-2HA22-0KT0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RH2921-2HA22-0KT0 auxiliary switch, snap-on mounting for contactor sizes S00, S0, S2, S3, 2 instantaneous contacts, IP20 front, 10 A at 24 V rated operational current.","salesMarkdown":"## Snap-on auxiliary switch for SIRIUS contactors This is a Siemens SIRIUS auxiliary switch — order code 3RH2921-2HA22-0KT0 — designed to snap onto the front of SIRIUS contactors in sizes S00, S0, S2, and S3. It adds two instantaneous normally-open contacts to the contactor relay or power contactor assembly, giving you extra signal feedback or control logic without a separate relay block. ## Current ratings across the voltage range The thermal current rating is 10 A at 24 V, but the actual switching capacity depends on the circuit voltage. At 24 V it handles 6 A; at 48 V and 60 V it drops to 2 A; at 110 V it's 1 A; at 230 V it's 6 A again (note the AC-15 style curve); at 400 V it's 3 A. The rated operational current figures tell a similar story: 10 A at 24 V, 4.7 A at 60 V, 3 A at 110 V, 1.2 A at 220 V, 0.5 A at 440 V, and 0.26 A at 600 V. These numbers matter when you're sizing the auxiliary circuit — a 24 VDC pilot light pulls different current than a 400 VAC contactor coil. ## Mirror contact and contact reliability This auxiliary switch carries a mirror contact per IEC 60947-4-1 when used with 3RT2 contactors — meaning the normally-closed contact mechanically mirrors the main contact position, critical for safety circuits that need to verify the main contacts have opened. Contact reliability is specified at 1 faulty switching per 100 million operations at 17 V, 1 mA, which covers dry switching of PLC inputs without contact wetting. ## Mounting and panel fit Snap-on mounting to the contactor front — no tools, no DIN rail space consumed. The dimensions are 36 mm wide, 47.7 mm deep, and 41.5 mm high, so it adds about 48 mm to the contactor depth. The front face is IP20 rated, meaning finger-safe but not washdown. Surge voltage resistance is 6 kV, which covers most industrial control panel transient environments.","metaTitle":"Siemens 3RH2921-2HA22-0KT0 SIRIUS Auxiliary Switch","metaDescription":"Siemens 3RH2921-2HA22-0KT0 SIRIUS auxiliary switch, snap-on for S00-S3 contactors. Rated 10 A at 24 V, IP20, mirror contact per IEC 60947-4-1.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Contactors"],"specifications":{"Depth":"47.7 mm","Width":"36 mm","title":"3RH2921-2HA22-0KT0","Height":"41.5 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","description":"auxiliary switch, on the front, 2 NO + 2 NC, 31/32, 41/42, 53/54, 63/64, current path: 1 NC, 1 NC, 1 NO, 1 NO, 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","Product Category":"Auxiliary switch","Lagging Switching":"0","Size Of Contactor":"S00, S0, S2, S3","Solid Or Stranded":"2x (0.5 ... 2.5 mm²)","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":"for snapping onto the front","Instantaneous Contact":"2","Substance Prohibitance (Date)":"10/01/2009","protection class IP on the front":"IP20","Surge Voltage Resistance Rated Value":"6 kV","for AWG cables for auxiliary contacts":"2x (20 ... 14)","Finely Stranded With Core End Processing":"2x (0.5 ... 1.5 mm²)","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","Finely Stranded Without Core End Processing":"2x (0.5 ... 2.5 mm²)","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":"spring-loaded terminals","insulation voltage with degree of pollution 3 at AC rated value":"690 V","number of CO contacts of auxiliary contacts instantaneous contact":"0","AWG number as coded connectable conductor cross section for auxiliary contacts":"20 ... 14"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$7.12","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/08b176f853c0ca7cb56a815c02869f12.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=878011&mlfb=3RH2921-2HA22-0KT0"},"ai":{"faq":[{"question":"What contactor sizes does 3RH2921-2HA22-0KT0 fit?","answer":"It snaps onto SIRIUS contactors in sizes S00, S0, S2, and S3. The product is designed for snapping onto the front of the contactor relay or power contactor."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RH2921-2HA22-0KT0","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/3RH2921-2HA22-0KT0 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}}