{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SL7420-3RC","brand":"Siemens","brandSlug":"siemens","productSlug":"5SL7420-3RC","canonicalUrl":"https://aoctrl.com/siemens/5SL7420-3RC","factsUrl":"https://aoctrl.com/api/mcp/products/5SL7420-3RC","rawCanonicalId":null},"summary":{"shortDescription":"Siemens 5SL7420-3RC, miniature circuit breaker, 20A, 4-pole, K characteristic, 15kA breaking capacity.","salesMarkdown":"The Siemens 5SL7420-3RC is a 4-pole miniature circuit breaker (MCB) rated at 20 A with a K-trip characteristic and a 15 kA breaking capacity. The K curve is designed for motor and transformer loads where inrush currents are higher than resistive loads — it holds through the start-up surge without nuisance tripping, then clears fast on a hard fault. The 15 kA short-circuit rating means it can safely interrupt faults up to that level on a 400 V three-phase panel, which covers most industrial distribution boards fed from a standard transformer. Snaps onto standard 35 mm DIN rail inside a distribution board or control panel. Four-pole width (72 mm at 18 mm per pole) means it occupies four module spaces. The K characteristic is the deciding spec for motor branch circuits — if the load is a pump or fan with a DOL start, this holds the inrush; if the load is lighting or a resistive heater, a B or C curve would be a tighter fit. Terminal capacity accepts up to 25 mm² conductor. The 15 kA breaking capacity at 400 V AC is the key coordination figure for the panel designer — it determines the upstream fault level the MCB must clear without welding contacts or failing to interrupt. For a typical 630 kVA transformer with around 20 kA prospective fault current at the main board, this MCB needs a current-limiting upstream device or a higher-rated MCCB ahead of it to stay within its 15 kA rating. Standard practice: verify the available fault current at the point of installation before committing the BOM line.","metaTitle":"Siemens 5SL7420-3RC MCB, 20A 4-pole K char 15kA","metaDescription":"Siemens 5SL7420-3RC miniature circuit breaker, 20A, 4-pole, K characteristic, 15kA breaking capacity. Current lifecycle stage. Sourced to order against an RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Miniature Circuit Breakers (MCB)"],"specifications":{"title":"5SL7420-3RC","description":"Miniature Circuit Breaker 20A 4-pole K characteristic 15kA","lifecycle_stage":"current"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/72af359decc3376336ce10b9942b6ec3.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=1502432&mlfb=5SL7420-3RC"},"ai":{"faq":[{"question":"What is the breaking capacity of the 5SL7420-3RC?","answer":"The 5SL7420-3RC has a 15 kA breaking capacity, which is the maximum fault current it can safely interrupt at its rated voltage."},{"question":"What does the K characteristic mean on this MCB?","answer":"The K characteristic is designed for motor and transformer loads, allowing it to withstand higher inrush currents during startup without tripping, while still providing fast short-circuit protection."},{"question":"Where can I buy the 5SL7420-3RC?","answer":"This part is sourced and quoted to order against an RFQ through independent distribution channels. Availability and current pricing are confirmed at quote time."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SL7420-3RC","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/5SL7420-3RC when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-08-11T15:51:03.652Z","lastPublished":"2026-08-11T15:51:03.652Z","indexable":true}}