{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3VA9978-0AB22","brand":"Siemens","brandSlug":"siemens","productSlug":"3VA9978-0AB22","canonicalUrl":"https://aoctrl.com/siemens/3VA9978-0AB22","factsUrl":"https://aoctrl.com/api/mcp/products/3VA9978-0AB22","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON, electrical alarm switch, changeover contacts type HQ (7 mm), accessory for 3VA6 circuit breakers, 6 A thermal current, 250 V DC max, overvoltage category III, pollution degree 3.","salesMarkdown":"## What this accessory does in the panel The Siemens SENTRON 3VA9978-0AB22 is an electrical alarm switch with changeover contacts (type HQ, 7 mm width) designed as an accessory for 3VA6 molded-case circuit breakers. It mounts inside the breaker accessory slot and tracks the breaker's tripped or switched state, giving the control system a hardwired signal — no separate monitoring relay needed. Rated for a thermal current of 6 A, it switches AC control loads up to 6 A in resistive duty (AC-12) and 3 A in inductive solenoid duty (AC-15) across 12–240 V. On DC control circuits, it handles 6 A at 12 V (DC-12) and derates to 0.8 A at 24 V (DC-13) for solenoid valves or contactor coils. The 4 kV surge voltage resistance and overvoltage category III rating mean it's built for the transient environment inside a main distribution panel, not just a clean control cabinet. ## Switching capacity by duty — the real fit check The 3VA9978-0AB22's switching ratings are given per IEC duty class, and the right one decides whether the contact holds up. For AC resistive loads (AC-12) — think panel indicators, relay coils, or PLC digital inputs — it's good for 6 A at any voltage from 12 V to 240 V. For AC solenoid or contactor coils (AC-15), the make/break current drops to 3 A across the same voltage range; that's the inductive inrush that welds undersized contacts. On DC, the derating is steeper: at 24 V it switches 4 A in DC-12 (resistive) but only 0.8 A in DC-13 (solenoid/valve). At 110 V DC, DC-13 drops to 0.2 A — enough for a small contactor hold coil, not a power circuit. ## Wiring and integration notes Strip length is 15 mm (0.6 in) for the screw terminals — use a ferrule on stranded wire to avoid whiskers under the clamp. The changeover contacts (form C) give one normally-open and one normally-closed signal from the same trip event, so you can wire a fault lamp to the NO and a PLC alarm input to the NC without extra relays. The 7 mm width fits the standard 3VA6 accessory slot; no DIN-rail space consumed beyond the breaker itself. Verify free-wheel diode polarity on any DC solenoid load switched through the DC-13 contact — the 0.8 A at 24 V rating assumes the coil's inductive kick is suppressed.","metaTitle":"Siemens 3VA9978-0AB22 SENTRON Electrical Alarm Switch, 6 A","metaDescription":"Siemens SENTRON 3VA9978-0AB22 electrical alarm switch for 3VA6 breakers. Rated 6 A thermal current, changeover contacts. Active production. Sourced to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Circuit Breaker Accessories"],"specifications":{"title":"3VA9978-0AB22","Maximum":"16","Minimum":"20","Accessories":"Electrical alarm switch","description":"electrical alarm switch changeover contacts type HQ (7mm) accessory for: 3VA6","Stripped Length":"15 mm","Thermal Current":"6 A","lifecycle_stage":"current","Product Brand Name":"SENTRON","at AC-12 / at 12 V":"6 A","at AC-12 / at 24 V":"6 A","at AC-12 / at 48 V":"6 A","at AC-15 / at 12 V":"3 A","at AC-15 / at 24 V":"3 A","at AC-15 / at 48 V":"3 A","at DC-12 / at 12 V":"6 A","at DC-12 / at 24 V":"4 A","at DC-12 / at 48 V":"2 A","at DC-13 / at 12 V":"1 A","at DC-13 / at 24 V":"0.8 A","at DC-13 / at 48 V":"0.4 A","Degree Of Pollution":"3","Product Designation":"Electrical alarm switch","at AC-12 / at 125 V":"6 A","at AC-15 / at 125 V":"3 A","at DC-12 / at 110 V":"0.5 A","at DC-12 / at 250 V":"0.25 A","at DC-13 / at 110 V":"0.2 A","at DC-13 / at 250 V":"0.1 A","Overvoltage Category":"III","Stripped Length [In]":"0.6 in","Design Of The Product":"Accessories for 3VA circuit breakers","at AC-12 / at 220/240 V":"6 A","at AC-15 / at 220/240 V":"3 A","Surge Voltage Resistance":"4 kV","operating voltage / at DC / rated value / minimum":"250 V"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/1ba0250c146c13e796b77adc8197870e.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=650511&mlfb=3VA9978-0AB22"},"ai":{"faq":[{"question":"How do I get current pricing and availability for 3VA9978-0AB22?","answer":"The 3VA9978-0AB22 is sourced and quoted to order against an RFQ through independent distribution. Current pricing and availability are confirmed at the time of quote — submit an RFQ for a firm price and lead time."},{"question":"Will 3VA9978-0AB22 drop into a panel that was specified around 5SY4140-7 without rewiring?","answer":"No — the 3VA9978-0AB22 is an accessory for the 3VA6 molded-case circuit breaker platform, while the 5SY4140-7 is a miniature circuit breaker (MCB) on a different mounting footprint. The alarm switch fits only the 3VA6 accessory slot and does not mount on a 5SY series breaker."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3VA9978-0AB22","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/3VA9978-0AB22 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}}