{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SU1644-2RC40","brand":"Siemens","brandSlug":"siemens","productSlug":"5SU1644-2RC40","canonicalUrl":"https://aoctrl.com/siemens/5SU1644-2RC40","factsUrl":"https://aoctrl.com/api/mcp/products/5SU1644-2RC40","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SU1644-2RC40, RCBO, 40 A, 4-pole, 8 modules, D characteristic, Type AC 300 mA.","salesMarkdown":"It uses a D tripping characteristic for the overcurrent element and a Type AC 300 mA residual current detection for the RCD side. The 8-module width (roughly 144 mm on a standard DIN rail) is the physical footprint you need to reserve in the distribution board — it occupies four 18 mm pole spaces per module, so plan the enclosure fill factor accordingly. The 40 A rating governs the upstream protective device coordination and the downstream cable sizing: this RCBO is the final circuit protection, not a main switch. With a D characteristic, the instantaneous trip threshold sits at 400–800 A, which lets it ride through the magnetizing inrush of a 40 A-rated transformer or a bank of contactor coils without dropping the circuit. ## RCD type and application The Type AC residual current detection (300 mA) responds to sinusoidal AC fault currents only. For circuits with variable-speed drives, switched-mode power supplies, or UPS-fed loads, a Type A or Type B RCD would be required — the Type AC element here will not reliably detect smoothed DC or pulsed fault currents from those sources.","metaTitle":"Siemens 5SU1644-2RC40 RCBO, 40 A, 4-pole, D curve, 300 mA AC","metaDescription":"Siemens 5SU1644-2RC40 RCBO, 40 A, 4-pole, 8 modules, D characteristic, Type AC 300 mA. Current lifecycle stage. Sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Residual Current Breakers (RCCB/RCBO)"],"specifications":{"lifecycle_stage":"current"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/bed74928c9539d6c50f1eb1e06da07d1.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=405866&mlfb=5SU1644-2RC40","alternativesUrl":"https://aoctrl.com/api/mcp/products/5SU1644-2RC40/alternatives.json"},"ai":{"faq":[{"question":"Where can I buy the 5SU1644-2RC40 and get a price?","answer":"This RCBO is sourced and quoted to order through independent distribution. Submit an RFQ for current availability and pricing — confirmed at quote time."},{"question":"What is the 5SU1644-2RC40's description?","answer":"The 5SU1644-2RC40 is an RCBO rated 40 A, 4-pole, 8 modules, D characteristic, Type AC 300 mA residual current."},{"question":"What does the D characteristic mean on this RCBO?","answer":"The D tripping characteristic means the magnetic short-circuit release operates at 10–20 times the rated current (400–800 A for this 40 A unit). This is intended for circuits with high inrush currents that would cause nuisance tripping on B or C curve breakers."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SU1644-2RC40","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/5SU1644-2RC40 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-09-02T08:15:54.622Z","lastPublished":"2026-09-02T08:15:54.622Z","indexable":true}}