{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3VA9978-0BB25","brand":"Siemens","brandSlug":"siemens","productSlug":"3VA9978-0BB25","canonicalUrl":"https://aoctrl.com/siemens/3VA9978-0BB25","factsUrl":"https://aoctrl.com/api/mcp/products/3VA9978-0BB25","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON, undervoltage release accessory, 208-230V AC 50/60Hz, 2 VA, 4 kV surge voltage resistance, pollution degree 3, for 3VA4/5/6. Order code 3VA9978-0BB25.","salesMarkdown":"The Siemens SENTRON 3VA9978-0BB25 is an undervoltage release accessory that trips the parent breaker when the control voltage drops. It operates on a 208-230 V AC supply at 50/60 Hz. The 2 VA maximum apparent power draw is low enough that it won't load the control transformer on a multi-device string. The accessory occupies 3 slots in the 3VA breaker's accessory bay — a standard fit for this family. Dimensions are 25.7 mm wide, 65.1 mm high, and 28.8 mm deep, so it nests entirely within the breaker envelope without increasing the panel footprint. The auxiliary circuit connection accepts AWG 18 to 750 mm² wire; strip length is 10 mm (0.4 in). This is a snap-in accessory for the 3VA4/5/6 line — no DIN-rail space consumed beyond the breaker itself. The 4 kV surge rating and overvoltage category III mean it's rated for the distribution side of a building's main panel, not just downstream sub-panels.","metaTitle":"Siemens 3VA9978-0BB25 SENTRON Undervoltage Release, 208-230V","metaDescription":"Siemens 3VA9978-0BB25 SENTRON undervoltage release accessory for 3VA4/5/6 breakers. 208-230V AC 50/60Hz, 2 VA, 4 kV surge, pollution degree 3. Active production, sourced to order.","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":"3VA9978-0BB25","Height":"65.1 mm","Accessories":"Auxiliary release","description":"undervoltage release 208-230V AC 50/60Hz accessory for: 3VA4/5/6","Number Of Slots":"3","Stripped Length":"10 mm","lifecycle_stage":"current","Product Brand Name":"SENTRON","Degree Of Pollution":"3","Product Designation":"Accessories","Overvoltage Category":"III","Stripped Length [In]":"0.4 in","Design Of The Product":"Auxiliary release","Surge Voltage Resistance":"4 kV","Apparent Power Consumption / Maximum":"2 VA","Type Of Electrical Connection / For Auxiliary Circuit":"AWG18 / 750 mm"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/ebbcb7989d23c3997929ca1e308f0998.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=650526&mlfb=3VA9978-0BB25"},"ai":{"faq":[{"question":"What is 3VA9978-0BB25 used for?","answer":"It's an undervoltage release accessory for Siemens SENTRON 3VA4, 3VA5, and 3VA6 molded-case circuit breakers. It trips the breaker when the control voltage (208-230 V AC) drops below the dropout threshold, typically used to prevent automatic restart after a power loss."},{"question":"Will 3VA9978-0BB25 fit a panel built around a 5SY4140-7 breaker?","answer":"No — the 3VA9978-0BB25 is an accessory for the 3VA4/5/6 frame breakers only. The 5SY4140-7 is a miniature circuit breaker (SENTRON 5SY series) with a completely different accessory interface; this undervoltage release will not physically mount to it."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3VA9978-0BB25","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/3VA9978-0BB25 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}}