{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RH2122-2UB40","brand":"Siemens","brandSlug":"siemens","productSlug":"3RH2122-2UB40","canonicalUrl":"https://aoctrl.com/siemens/3RH2122-2UB40","factsUrl":"https://aoctrl.com/api/mcp/products/3RH2122-2UB40","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RH2122-2UB40 auxiliary contactor, size S00, 24 V DC coil with integrated varistor, 2 NO instantaneous contacts, screw and snap-on 35 mm DIN rail mounting, 73 mm depth, 45 mm width, 70 mm height.","salesMarkdown":"## Size S00 auxiliary contactor with varistor coil suppression The Siemens 3RH2122-2UB40 is a SIRIUS auxiliary contactor in frame size S00, designed for switching control and signal circuits rather than main motor loads. Its 24 V DC coil includes a built-in varistor for surge suppression, which clips inductive voltage spikes at coil dropout — a detail that matters when the contactor shares a DC supply with sensitive PLC inputs or fieldbus slices. ## Panel fit and mounting clearances The 3RH2122-2UB40 measures 45 mm wide, 73 mm deep, and 70 mm tall — a compact footprint for a 2-pole auxiliary block. These clearances allow arc gases to vent and heat to dissipate; packing the contactor tighter than these figures derates the switching capacity, especially on DC loads where the arc lingers longer. ## Switching duty and contact configuration The contactor provides 2 NO instantaneous contacts. Mechanical endurance is 30 million typical cycles, which suits high-cycle applications like conveyor interlocking or valve sequencing where the auxiliary contactor sees every machine cycle. The DC coil closing power is 4 W — a modest draw that a 24 V DC power supply can handle without oversizing. The product extension auxiliary switch is available, meaning additional contact blocks can be stacked onto this base unit without removing wiring.","metaTitle":"Siemens 3RH2122-2UB40 SIRIUS Auxiliary Contactor, 24 VDC","metaDescription":"Siemens 3RH2122-2UB40 SIRIUS auxiliary contactor, size S00, 24 VDC coil with varistor, 2 NO contacts, rated 10 A at 24 V. Screw and DIN rail mount.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Contactors"],"specifications":{"Depth":"73 mm","Width":"45 mm","at AC":"10 000 1/h","at DC":"7 ... 13 ms","title":"3RH2122-2UB40","Height":"70 mm","Upwards":"10 mm","Forwards":"10 mm","Downwards":"10 mm","Arcing Time":"10 ... 15 ms","At The Side":"6 mm","Rated Value":"24 V","description":"Contactor relay, 2 NO + 2 NC, 24 V DC, integrated varistor Size S00, Spring-type terminal","Initial Value":"0.8","During Storage":"-55 ... +80 °C","lifecycle_stage":"current","During Operation":"-25 ... +60 °C","Fastening Method":"screw and snap-on mounting onto 35 mm standard mounting rail","Full-Scale Value":"1.1","Mounting Position":"+/-180° rotation possible on vertical mounting surface; can be tilted forward and backward by +/- 22.5° on vertical mounting surface","Size Of Contactor":"S00","Solid Or Stranded":"2x (0,5 ... 4 mm²)","Product Brand Name":"SIRIUS","Degree Of Pollution":"3","Product Designation":"Auxiliary contactor","at 24 V rated value":"10 A","at 60 V rated value":"4.7 A","Of Contactor Typical":"30 000 000","at 110 V rated value":"3 A","at 220 V rated value":"1.2 A","at 230 V rated value":"10 A","at 400 V rated value":"3 A","at 440 V rated value":"0.5 A","at 500 V rated value":"2 A","at 600 V rated value":"0.26 A","at 690 V rated value":"1 A","Instantaneous Contact":"2","Relative Humidity Minimum":"10 %","Substance Prohibitance (Date)":"10/01/2009","Design Of The Surge Suppressor":"with varistor","Product Extension Auxiliary Switch":"Yes","closing power of magnet coil at DC":"4 W","holding power of magnet coil at DC":"4 W","Surge Voltage Resistance Rated Value":"6 kV","at AWG cables for auxiliary contacts":"2x (20 ... 12)","operating frequency at DC-12 maximum":"1 000 1/h","operating frequency at DC-13 maximum":"1 000 1/h","operational current at AC-12 maximum":"10 A","reference code according to IEC 81346-2":"K","Finely Stranded With Core End Processing":"2x (0.5 ... 2.5 mm²)","Contact Reliability Of Auxiliary Contacts":"1 faulty switching per 100 million (17 V, 1 mA)","with low demand rate according to SN 31920":"40 %","Finely Stranded Without Core End Processing":"2x (0.5 ... 2.5 mm²)","with high demand rate according to SN 31920":"73 %","number of NC contacts for auxiliary contacts":"2","number of NO contacts for auxiliary contacts":"2","Type Of Voltage Of The Control Supply Voltage":"DC","contact rating of auxiliary contacts according to UL":"A600 / Q600","Identification Number And Letter For Switching Elements":"22 E","Installation Altitude At Height Above Sea Level Maximum":"2 000 m","Of The Contactor With Added Auxiliary Switch Block 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","Of The Contactor With Added Electronically Optimized Auxiliary Switch Block Typical":"5 000 000","Design Of The Fuse Link For Short-Circuit Protection Of The Auxiliary Switch Required":"fuse gL/gG: 10 A","design of the miniature circuit breaker for short-circuit protection of the auxiliary circuit up to 230 V":"C characteristic: 6 A; 0.4 kA"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/37f58597da7f4796e6ed939714999352.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=397685&mlfb=3RH2122-2UB40"},"ai":{"faq":[{"question":"What is the 3RH2122-2UB40 rated to switch at 24 V DC?","answer":"At 24 V rated value the contactor carries 10 A. At 60 V DC it carries 4.7 A, at 110 V DC 3 A, and at 220 V DC 1.2 A. The DC switching arc time is 7 to 13 ms, so the contact gap and varistor suppression handle the DC arc within those current limits."},{"question":"Does the 3RH2122-2UB40 include surge suppression?","answer":"Yes, the design of the surge suppressor is with varistor. The varistor is integrated into the coil circuit, clamping voltage transients when the coil de-energizes. This reduces EMI and protects nearby electronics — useful when the contactor shares a 24 V DC bus with PLC I/O or fieldbus nodes."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RH2122-2UB40","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/3RH2122-2UB40 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-22T19:47:38.189Z","lastPublished":"2026-07-22T19:47:38.189Z","indexable":true}}