{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3VA9978-0BB12","brand":"Siemens","brandSlug":"siemens","productSlug":"3VA9978-0BB12","canonicalUrl":"https://aoctrl.com/siemens/3VA9978-0BB12","factsUrl":"https://aoctrl.com/api/mcp/products/3VA9978-0BB12","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 3VA9978-0BB12 undervoltage release accessory, 48V DC coil, for 3VA4/5/6 series breakers, 690V rated insulation voltage, 4kV surge resistance, 3 slots, pollution degree 3, overvoltage category III.","salesMarkdown":"The Siemens 3VA9978-0BB12 is a SENTRON undervoltage release — an auxiliary accessory that trips a 3VA4, 3VA5, or 3VA6 molded-case circuit breaker when its 48 V DC control voltage drops below the dropout threshold. It's a panel-mount add-on that snaps into the breaker's accessory slots, not a standalone device. The release draws a maximum of 2.5 W from the DC control circuit at steady state. That's the coil holding power once the breaker is closed; the momentary pickup surge is higher but brief. Dimensions are 25.7 mm wide, 65.1 mm high, and 28.8 mm deep — it's a compact module that fits inside the breaker's accessory bay. The 3-slot design means it occupies one of the three available positions in the 3VA frame. Wire stripping length is 10 mm (0.4 in) for the AWG 18 / 750 mm connection. That's standard for spring-cage or screw terminals on this class of auxiliary; strip to that length and no more to avoid exposed conductor outside the clamp.","metaTitle":"Siemens 3VA9978-0BB12 SENTRON Undervoltage Release, 48V DC","metaDescription":"Siemens 3VA9978-0BB12 SENTRON undervoltage release accessory for 3VA4/5/6 breakers. 48V DC coil, 690V rated insulation voltage, 4kV surge. Active production. Sourced to order again","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Circuit Breaker Accessories"],"specifications":{"Depth":"28.8 mm","Width":"25.7 mm","title":"3VA9978-0BB12","Height":"65.1 mm","Accessories":"Auxiliary release","description":"undervoltage release 48V DC accessory for: 3VA4/5/6","Number of slots":"3","Product version":"Auxiliary release","lifecycle_stage":"current","Product brand name":"SENTRON","Degree of pollution":"3","Product designation":"Accessories","Overvoltage category":"III","Wire stripping length":"10 mm","Surge voltage resistance":"4 kV","Wire stripping length [in]":"0.4 in","Rated insulation voltage Ui":"690 V","Type of auxiliary circuit connection":"AWG18 / 750 mm","Consumed active power / at DC / maximum":"2.5 W"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/3257c26f0412ec87bb6e3cf848dca97e.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=650521&mlfb=3VA9978-0BB12"},"ai":{"faq":[{"question":"How do I get current pricing and availability for 3VA9978-0BB12?","answer":"This part is sourced to order through independent distribution. Submit an RFQ; pricing and stock are confirmed at quote time."},{"question":"What is 3VA9978-0BB12's depth?","answer":"The listed depth is 28.8 mm, with a width of 25.7 mm and height of 65.1 mm."},{"question":"Will 3VA9978-0BB12 drop into a panel specified around 5SY4140-7?","answer":"No — the 5SY4140-7 is a miniature circuit breaker, not an accessory. The 3VA9978-0BB12 is an undervoltage release that mounts inside a 3VA4/5/6 breaker frame, not a standalone breaker. Different form factor, different wiring, different BOM line."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3VA9978-0BB12","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/3VA9978-0BB12 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}}