{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"6EP1961-3BA21","brand":"Siemens","brandSlug":"siemens","productSlug":"6EP1961-3BA21","canonicalUrl":"https://aoctrl.com/siemens/6EP1961-3BA21","factsUrl":"https://aoctrl.com/api/mcp/products/6EP1961-3BA21","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SITOP buffer module, 6EP1961-3BA21, 40 A aggregate current, 96.6% efficiency, DIN rail mount, IP20, SELV isolated relay output.","salesMarkdown":"The Siemens 6EP1961-3BA21 is a DC buffer module that bridges short mains interruptions for 24 V DC loads. It delivers up to 40 A aggregate current from a 24 to 28.8 V DC input, with the output voltage following the input minus roughly 0.5 V. The controlled, isolated DC output is backed by a relay contact (changeover, rated 8 A at 240 V AC or 24 V DC) that signals OK when both input voltages stay above an adjustable threshold of 20 to 25 V. At 96.6% efficiency, the module wastes little heat in the cabinet — important when the 70 × 125 × 120 mm enclosure relies on natural convection over the -25 to +60 °C operating range. Above +60 °C, derate the 40 A aggregate by 3% per Kelvin up to +70 °C. Snaps onto DIN rail EN 60715 35×7.5/15. The 70 mm width occupies three standard 22.5 mm module positions. Allow 50 mm clearance above and below for convection airflow and wiring access — the top and bottom clearance figures are 50 mm each, with 0 mm left and right clearance needed. Input, output, and ground terminate via one screw terminal each accepting 0.33 to 10 mm² single-core or finely stranded wire. Protection class is IP20 — suitable for dry, enclosed control cabinets only. Carries CE, cULus-Listed (UL 508, CSA C22.2 No. 107.1, File E197259), EAC, and shipbuilding approvals from ABS and DNV GL. Galvanic isolation is SELV per EN 60950-1. Conducted and radiated emissions meet EN 55022 Class B; immunity complies with EN 61000-6-2. Not ATEX, IECEx, or FM registered, and not NEC Class 2. ## Reliability and storage MTBF at 40 °C is 6,471,654 hours — roughly 739 years continuous, a figure that reflects the semiconductor-grade design. Storage and transport range is -40 to +85 °C. Specifications are stated at rated input voltage and +25 °C ambient unless otherwise noted.","metaTitle":"Siemens 6EP1961-3BA21 DC buffer module, 40 A, DIN rail, 96.6","metaDescription":"Siemens 6EP1961-3BA21 DC buffer module, 40 A aggregate, 96.6% efficiency, SELV isolation, UL 508 listed. Active production, sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["DIN Rail Power Supplies"],"specifications":{"Top":"50 mm","ATEX":"No","Left":"0 mm","IECEx":"No","Right":"0 mm","at DC":"24 ... 28.8 V","title":"6EP1961-3BA21","Bottom":"50 mm","C-Tick":"No","DNV GL":"Yes","At Input":"Input, output and ground: 1 screw terminal each for 0.33 ... 10 mm² single-core/finely stranded","CE marking":"Yes","NEC Class 2":"No","Rated Range":"40 A; max. aggregate current 40 A; +60 ... +70 °C: derating 3%/K","Rated Value":"40 A","UL approval":"Yes; cULus-Listed (UL 508, CSA C22.2 No. 107.1), File E197259","description":"SITOP PSE202U redundancy module input/output: 24 V DC/40 A suitable for decoupling two SITOP power supplies with maximal per 20 A output current *Ex approval no longer available*","CSA approval":"Yes; cULus-Listed (UL 508, CSA C22.2 No. 107.1), File E197259","EAC approval":"Yes","During Storage":"-40 ... +85 °C","MTBF at 40 °C":"6 471 654 h","FM registration":"No","lifecycle_stage":"current","During Operation":"-25 ... +60 °C; with natural convection","During Transport":"-40 ... +85 °C","Fastening Method":"Snaps onto DIN rail EN 60715 35x7.5/15","Other Information":"Specifications at rated input voltage and ambient temperature +25 °C (unless otherwise specified)","ULhazloc approval":"No","Galvanic Isolation":"yes, SELV acc. to EN 60950-1 (relay contact)","protection class IP":"IP20","Efficiency In Percent":"96.6 %","Shipbuilding Approval":"ABS, DNV GL","Depth Of The Enclosure":"120 mm","For Auxiliary Contacts":"Relay contact: 3 screw terminals for 0.5 ... 2.5 mm² single-core/finely stranded","Width Of The Enclosure":"70 mm","Height Of The Enclosure":"125 mm","Voltage Curve At Output":"Controlled, isolated DC voltage","For Emitted Interference":"EN 55022 Class B","Nippon Kaiji Kyokai (NK)":"No","Type Of Signal At Output":"Isolated relay contact (changeover contacts, rating 8 A/240 V AC, 24 V DC): Signals OK if both input voltages > switching threshold, setting range of threshold 20 ... 25 V","For Interference Immunity":"EN 61000-6-2","Formula For Output Voltage":"Vin - approx. 0.5 V","cCSAus, Class 1, Division 2":"No","Type Of Electrical Connection":"screw-type terminals","at output 1 at DC rated value":"24 V","During NO-Load Operation Maximum":"1.5 W","Type Of The Power Supply Network":"DC voltage","output voltage at DC rated value":"24 V","Lloyds Register of Shipping (LRS)":"No","Operating Resource Protection Class":"Class III","Display Version For Normal Operation":"Green LED for \"both Input voltages > switching threshold\"; red LED: for \"at least one input voltage < switching threshold\"","French marine classification society (BV)":"No","Product Function Output Voltage Adjustable":"No","American Bureau of Shipping Europe Ltd. (ABS)":"Yes","environmental category according to IEC 60721":"Climate class 3K3, 5 … 95% no condensation","Product Feature Of The Enclosure Housing Can Be Lined Up":"Yes","At Rated Output Voltage For Rated Value Of The Output Current Typical":"34 W"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$134.20","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/f37a65f1dd8683e0e9ce54b69405cfd5.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=304328&mlfb=6EP1961-3BA21"},"ai":{"faq":[{"question":"What is the 40 A rating and when does derating apply?","answer":"The 40 A is the maximum aggregate current at +25 °C. Above +60 °C ambient, derate by 3% per Kelvin up to +70 °C. Below that temperature, the full 40 A is available across the 24 to 28.8 V DC input range."},{"question":"Where can I buy 6EP1961-3BA21?","answer":"This module is sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time — submit an RFQ for a firm commercial response."},{"question":"What compliance documentation does Siemens provide for 6EP1961-3BA21?","answer":"Siemens provides CE declaration, cULus listing (UL 508, CSA C22.2 No. 107.1, File E197259), EAC certificate, and shipbuilding approvals from ABS and DNV GL. Emissions meet EN 55022 Class B; immunity meets EN 61000-6-2. Galvanic isolation is SELV per EN 60950-1."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/6EP1961-3BA21","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/6EP1961-3BA21 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}}