{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RV2821-4BD10","brand":"Siemens","brandSlug":"siemens","productSlug":"3RV2821-4BD10","canonicalUrl":"https://aoctrl.com/siemens/3RV2821-4BD10","factsUrl":"https://aoctrl.com/api/mcp/products/3RV2821-4BD10","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RV2821-4BD10 circuit breaker, S0 frame, for transformer protection per UL 489/CSA C22.2 No.5, 25 kA breaking capacity at 400 V AC, screw and snap-on 35 mm DIN rail mount.","salesMarkdown":"## Transformer-protection breaker, S0 frame — 25 kA at 400 V The Siemens 3RV2821-4BD10 is a SIRIUS circuit breaker in the S0 frame size, designed specifically for transformer protection and listed to UL 489 / CSA C22.2 No.5. The headline breaking capacity is 25 kA at 400 V AC (Icu per IEC 60947-2), with a 55 kA version at the same voltage — the higher figure likely reflects the Ics service rating. At 240 V AC it handles 100 kA. For fuse backup coordination, the spec calls for gG 63 A at 400 V, gG 50 A at 500 V, and gG 50 A at 690 V — meaning if you need higher interrupting capacity than the breaker alone provides, those are the upstream fuse sizes to coordinate with. ## Mounting and clearance — fits a standard S0 footprint Dimensions are 45 mm wide, 144 mm high, 97 mm deep — the S0 frame standard. That means you can butt it against a backplane or enclosure wall on the depth axis, but need breathing room vertically for arc quenching and heat dissipation. ## Terminals and wiring — screw-type, M4 main contacts Main contact screws are M4. Screwdriver shaft diameter 5 to 6 mm, Pozidriv size 2 tip. That's a standard Pozidriv #2 — common in European panel shops, but if your crew carries only Phillips, add the correct bit to the BOM. ## Environmental and operational limits Rated operational voltage range is 20 to 690 V. No ground fault detection, no phase failure detection built in. If those functions are required for your transformer circuit, they need to be handled externally by a separate monitoring relay or electronic overload. Maximum switching frequency at AC-3 and AC-3e duty is 15 operations per hour — fine for transformer inrush switching or infrequent motor starting, not for high-cycle applications like a rapid-reversing conveyor. Lifecycle stage is current — this is an active, in-production part from Siemens.","metaTitle":"Siemens 3RV2821-4BD10 SIRIUS Circuit Breaker, 25 kA at 400 V","metaDescription":"Siemens 3RV2821-4BD10 SIRIUS circuit breaker for transformer protection. 25 kA breaking capacity at 400 V AC. UL 489 listed. Screw and snap-on DIN rail mount. S0 frame. Available t","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Motor Protection Circuit Breakers (MPCB)"],"specifications":{"Depth":"97 mm","Width":"45 mm","Height":"144 mm","Upwards":"70 mm","Forwards":"0 mm","at 400 V":"gG 63 A","at 500 V":"gG 50 A","at 690 V":"gG 50 A","Backwards":"0 mm","Downwards":"70 mm","At The Side":"30 mm","Rated Value":"20 ... 690 V","During Storage":"-50 ... +80 °C","at AC-3 maximum":"15 1/h","lifecycle_stage":"current","During Operation":"-20 ... +60 °C","During Transport":"-50 ... +80 °C","Fastening Method":"screw and snap-on mounting onto 35 mm DIN rail according to DIN EN 50022","at AC-3e maximum":"15 1/h","For Main Contacts":"M4","Mounting Position":"any","Solid Or Stranded":"1 ... 10 mm², max. 2x 10 mm²","Product Brand Name":"SIRIUS","Product Designation":"Circuit breaker","at 230 V rated value":"5.5 kW","at 240 V rated value":"100 kA","at 400 V rated value":"25 kA","at 500 V rated value":"5 kA","at 690 V rated value":"2 kA","Design Of The Product":"For transformer protection according to UL 489/CSA C22.2 No.5","Ground Fault Detection":"No","Phase Failure Detection":"No","For Main Current Circuit":"screw-type terminals","at AC at 240 V rated value":"100 kA","at AC at 400 V rated value":"55 kA","at AC at 500 V rated value":"10 kA","at AC at 690 V rated value":"4 kA","Design Of Screwdriver Shaft":"Diameter 5 to 6 mm","Size Of The Circuit-Breaker":"S0","Size Of The Screwdriver Tip":"Pozidriv size 2","at AC-3 rated value maximum":"690 V","Of The Main Contacts Typical":"100 000","at AC in hot operating state":"10.5 W","at AC-3 at 400 V rated value":"20 A","at AC-3e rated value maximum":"690 V","Of Auxiliary Contacts Typical":"100 000","Substance Prohibitance (Date)":"10/01/2009","at AC-3e at 400 V rated value":"20 A","Design Of The Overload Release":"thermal","Operating Frequency Rated Value":"50 ... 60 Hz","Operational Current Rated Value":"20 A","at AWG cables for main contacts":"2x (14 ... 10)","Design Of The Short-Circuit Trip":"magnetic","Product Extension Auxiliary Switch":"Yes","Relative Humidity During Operation":"10 ... 95 %","Display Version For Switching Status":"Handle","Surge Voltage Resistance Rated Value":"6 kV","at AC in hot operating state per pole":"3.5 W","reference code according to IEC 81346-2":"Q","Finely Stranded With Core End Processing":"1 ... 16 mm², max. 6 + 16 mm²","Number Of Poles For Main Current Circuit":"3","Product Function Short Circuit Protection":"Yes","with low demand rate according to SN 31920":"50 FIT","For Main Contacts With Screw-Type Terminals":"2.5 ... 3 N·m","with high demand rate according to SN 31920":"50 %","shock resistance according to IEC 60068-2-27":"25 g / 11 ms (rectangular impulse and sine pulse)","Electrical Endurance (Operating Cycles) Typical":"100 000","at 480 AC Y/277 V according to UL 489 rated value":"50 kA","Installation Altitude At Height Above Sea Level Maximum":"2 000 m","Arrangement Of Electrical Connectors For Main Current Circuit":"Top and bottom","Response Value Current Of Instantaneous Short-Circuit Trip Unit":"325 A","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=279547&mlfb=3RV2821-4BD10","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RV2821-4BD10/alternatives.json"},"ai":{"faq":[{"question":"What are the mounting dimensions and clearance requirements?","answer":"45 mm wide, 144 mm high, 97 mm deep. Clearance: 70 mm above and below, 30 mm to the sides, zero forward or backward. Mounts on 35 mm DIN rail per DIN EN 50022."},{"question":"Will the 3RV2821-4BD10 drop into a panel specified for the 3RV2023-4CA10?","answer":"Both are S0 frame breakers on 35 mm DIN rail, so the physical footprint and mounting are identical. However, the 3RV2821-4BD10 is designed for transformer protection (UL 489), while the 3RV2023-4CA10 is a standard motor-protective breaker. Verify the protection curve and application before substituting — they are not electrically interchangeable without reviewing the coordination study."},{"question":"What compliance documentation is available for the 3RV2821-4BD10?","answer":"The breaker is UL 489 and CSA C22.2 No.5 listed for transformer protection. Standard Siemens documentation includes the CE declaration of conformity and RoHS/REACH compliance data. Specific certificates are available on request."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RV2821-4BD10","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/3RV2821-4BD10 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}}