{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3VA9978-0AA23","brand":"Siemens","brandSlug":"siemens","productSlug":"3VA9978-0AA23","canonicalUrl":"https://aoctrl.com/siemens/3VA9978-0AA23","factsUrl":"https://aoctrl.com/api/mcp/products/3VA9978-0AA23","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 3VA9978-0AA23, leading auxiliary switch, changeover contacts type HQ (7 mm), accessory for 3VA4/5/6 circuit breakers, 0.3 A thermal current, AC-15/DC-13 rated.","salesMarkdown":"The Siemens 3VA9978-0AA23 is a leading auxiliary switch from the SENTRON family, designed as a snap-on accessory for 3VA4, 3VA5, and 3VA6 molded-case circuit breakers. It provides a changeover contact set (type HQ, 7 mm width) that signals the breaker's ON/OFF state to a PLC, indicator lamp, or safety circuit. The 0.3 A thermal current rating (Ith) governs the continuous current the contacts can carry — sized for signal-level loads, not power switching. The contact ratings break down by utilization category. At AC-15 (solenoid/contactor control) and AC-12 (resistive) the switch handles 0.3 A at both 12 V and 24 V. On DC circuits the ratings are lower: DC-12 (resistive) at 0.1 A, DC-13 (solenoid/inductive) at 0.07 A — both at 12 V and 24 V. The 24 V minimum operating voltage means the switch needs at least that to reliably change state; don't expect it to work on a 12 V DC control bus. ## Environmental and installation specs The 4 kV rated surge voltage matches the insulation coordination of standard 400 V distribution panels. Strip length is 15 mm (0.6 in) for the wiring terminals. Contact operating time is 20 ms — fast enough for most signaling but not for high-speed counting.","metaTitle":"Siemens 3VA9978-0AA23 Leading Auxiliary Switch, 0.3 A","metaDescription":"Siemens SENTRON 3VA9978-0AA23 leading auxiliary switch for 3VA4/5/6 breakers. 0.3 A thermal current, AC-15/DC-13 rated, 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":{"title":"3VA9978-0AA23","Maximum":"16","Minimum":"20","Accessories":"Leading auxiliary switch","description":"leading changeover switch changeover contacts type HQ (7mm) electronic-comp. accessory for: 3VA4/5/6","Stripped Length":"15 mm","Thermal Current":"0.3 A","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":"Leading auxiliary switch","Overvoltage Category":"III","Stripped Length [In]":"0.6 in","Design Of The Product":"Accessories for 3VA circuit breakers","Surge Voltage Resistance":"4 kV","Lead Time / Relating To Main Contacts":"20 ms","operating voltage / at DC / rated value / minimum":"24 V"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$25.40","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/357ab43ee2d908a429890b3c61a34d00.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=650507&mlfb=3VA9978-0AA23"},"ai":{"faq":[{"question":"What is the thermal current rating of 3VA9978-0AA23?","answer":"The thermal current (Ith) is 0.3 A. This is the maximum continuous current the auxiliary switch contacts can carry — sized for signal-level loads like PLC inputs or indicator lamps, not power circuits."},{"question":"What breakers does the 3VA9978-0AA23 fit?","answer":"It's designed as a snap-on accessory for Siemens 3VA4, 3VA5, and 3VA6 molded-case circuit breakers. The leading auxiliary switch mounts on the left side of the breaker and signals the main contact position."},{"question":"Where can I buy 3VA9978-0AA23 and get current pricing?","answer":"This part is sourced to order against an RFQ through independent industrial automation distribution. Availability and current pricing are confirmed at quote time — submit an RFQ for a firm price and lead time."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3VA9978-0AA23","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/3VA9978-0AA23 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}}