{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SM3746-4BG","brand":"Siemens","brandSlug":"siemens","productSlug":"5SM3746-4BG","canonicalUrl":"https://aoctrl.com/siemens/5SM3746-4BG","factsUrl":"https://aoctrl.com/api/mcp/products/5SM3746-4BG","rawCanonicalId":null},"summary":{"shortDescription":"Siemens 5SM3746-4BG residual current operated circuit breaker, 4-pole, type B, short-time delayed, In: 63 A, 500 mA, Un AC: 400 V.","salesMarkdown":"The 5SM3746-4BG: The 63 A continuous rating matches the feeder or main switch in a distribution board feeding a mixed load. The 500 mA trip threshold is higher than a standard 30 mA RCCB — it's chosen where nuisance tripping from leakage in long cable runs or VFD-fed motors would take a 30 mA unit out. Type B detection covers DC ripple up to 6 mA smooth DC and frequencies up to 1 kHz, which is what you get from variable-frequency drives, UPS systems, and EV chargers. The short-time delay (typically 40–150 ms) gives selectivity with downstream 30 mA RCDs: a fault on a socket circuit clears without dropping the main board. The 4-pole form factor (3 phases + neutral) makes it the right choice for a three-phase supply with neutral. The 500 mA threshold is common for fire-protection RCDs in commercial installations — the building code often demands a 300 mA or 500 mA residual current device on the main switch to protect against arcing faults without tripping on normal leakage.","metaTitle":"Siemens 5SM3746-4BG Residual Current Circuit Breaker, Type B","metaDescription":"Siemens 5SM3746-4BG residual current circuit breaker, 4-pole type B, short-time delayed, 63 A, 500 mA, 400 V AC. Current production. Available to order via 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":null,"sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=1357587&mlfb=5SM3746-4BG","alternativesUrl":"https://aoctrl.com/api/mcp/products/5SM3746-4BG/alternatives.json"},"ai":{"faq":[{"question":"How do I get current pricing and availability for 5SM3746-4BG?","answer":"We source and quote this part to order against an RFQ. Submit a request and we'll confirm current pricing and availability at quote time."},{"question":"What does type B and short-time delayed mean on this RCCB?","answer":"Type B detects smooth DC fault currents and high-frequency AC residuals, not just 50/60 Hz sine waves — essential for VFD, UPS, and EV charger circuits. The short-time delay (selective) allows coordination with downstream 30 mA RCDs so a fault on a branch circuit doesn't trip the main switch."},{"question":"What is the closest pin-compatible alternative to 5SM3746-4BG?","answer":"Siemens offers a broad range of 4-pole RCCBs in the same footprint. The deciding factor is the trip characteristic: type B with 500 mA and short-time delay is a specific combination. For a direct drop-in, verify the terminal layout and width against the existing board — the 5SM3 series shares the same 4-module (72 mm) width across most ratings."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SM3746-4BG","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/5SM3746-4BG 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}}