{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3VA9978-0AB23","brand":"Siemens","brandSlug":"siemens","productSlug":"3VA9978-0AB23","canonicalUrl":"https://aoctrl.com/siemens/3VA9978-0AB23","factsUrl":"https://aoctrl.com/api/mcp/products/3VA9978-0AB23","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON electrical alarm switch, changeover contacts type HQ (7 mm), accessory for 3VA6 circuit breakers, 24 V AC/DC, 0.3 A thermal current.","salesMarkdown":"The Siemens SENTRON 3VA9978-0AB23 is an electrical alarm switch with changeover contacts (type HQ, 7 mm) designed as an accessory for 3VA6 circuit breakers. Rated for 24 V AC (50 Hz) or 24 V DC operation, with a thermal current limit (Ith) of 0.3 A — that's the continuous current the switch contacts can carry. The switching capacity varies by load type: 0.3 A under AC-12 (resistive) or AC-15 (inductive solenoid) at 12–24 V, and 0.1 A under DC-12 (resistive) at the same voltages. For DC-13 (inductive, e.g. contactor coils), it drops to 0.07 A. So if you're switching a 24 VDC contactor coil, stay under 70 mA or add an interposing relay. Rated impulse withstand voltage of 4 kV and overvoltage category III mean it's suited for fixed industrial installations — the kind of environment where you'd find a 3VA breaker in the first place. Degree of pollution 3 confirms it can handle conductive dust and humidity typical in control cabinets without conformal coating.","metaTitle":"Siemens SENTRON 3VA9978-0AB23 Electrical Alarm Switch, 24V","metaDescription":"Siemens SENTRON 3VA9978-0AB23 electrical alarm switch for 3VA circuit breakers. Active production, 24 V AC/DC, 0.3 A thermal current. Available to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Circuit Breaker Accessories"],"specifications":{"title":"3VA9978-0AB23","Maximum":"16","Minimum":"20","Accessories":"Electrical alarm switch","description":"electrical alarm switch changeover contacts type HQ (7mm) electronic-comp. accessory for: 3VA6","Product version":"Accessories for 3VA circuit breakers","Stripped Length":"15 mm","lifecycle_stage":"current","Product Brand Name":"SENTRON","at AC-12 / at 12 V":"0.3 A","at AC-12 / at 24 V":"0.3 A","at AC-15 / at 12 V":"0.3 A","at AC-15 / at 24 V":"0.3 A","at DC-12 / at 12 V":"0.1 A","at DC-12 / at 24 V":"0.1 A","at DC-13 / at 12 V":"0.07 A","at DC-13 / at 24 V":"0.07 A","Degree of pollution":"3","Product Designation":"Electrical alarm switch","Overvoltage category":"III","Stripped Length [In]":"0.6 in","Thermal current limit Ith":"0.3 A","Rated operational voltage Ue with DC":"24 V","Tension assignée de tenue aux chocs":"4 kV","Rated operational voltage Ue at AC 50 Hz":"24 V"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/4060714bdf1c1f04494ff48c5c963180.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=650512&mlfb=3VA9978-0AB23"},"ai":{"faq":[{"question":"Will 3VA9978-0AB23 drop into a panel that was specified around 5SY4140-7 without rewiring?","answer":"No — the 5SY4140-7 is a miniature circuit breaker, not an accessory. The 3VA9978-0AB23 is an electrical alarm switch that mounts onto a 3VA6 breaker's accessory slot. It doesn't replace or substitute a 5SY breaker; it adds a status-signal function to a 3VA breaker that already exists."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3VA9978-0AB23","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/3VA9978-0AB23 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}}