{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SM9422-0KK","brand":"Siemens","brandSlug":"siemens","productSlug":"5SM9422-0KK","canonicalUrl":"https://aoctrl.com/siemens/5SM9422-0KK","factsUrl":"https://aoctrl.com/api/mcp/products/5SM9422-0KK","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SM9422-0KK, RC unit electronic, 2-pole, type AC, In: 40 A, 100 mA, Un AC: 400 V.","salesMarkdown":"It's designed for instantaneous operation on 230/400 VAC, 50 Hz supply networks — standard European residential, commercial, and light industrial panels where the line frequency is fixed at 50 Hz. The 100 mA sensitivity makes this unit suitable for fire protection or general fault protection in circuits where a 30 mA device would cause nuisance tripping from normal leakage — think long cable runs, fixed equipment with some natural earth leakage, or sub-distribution boards. It's not a personal-protection device (that's the 30 mA class); 100 mA is about preventing cable overheating and arc faults. ## Thermal derating — the real-world current rating The 40 A nominal rating holds only at 40 °C ambient. Above that, the unit derates linearly: 37.2 A at 45 °C, 36 A at 50 °C, 34.8 A at 55 °C, 34 A at 60 °C, 33.2 A at 65 °C, and 32 A at 70 °C. If this RC unit lives in a crowded DIN-rail enclosure next to contactors or a transformer, expect the internal ambient to run 10–15 °C above the room temperature — size the upstream breaker accordingly, not off the 40 A nameplate. ## What the AC-type residual current means for the signal Type AC means this unit detects only sinusoidal AC residual currents — the classic sine-wave fault from a live-to-earth short on a linear load. It will not reliably detect pulsed DC, smooth DC, or high-frequency residuals from VFDs, LED drivers, or switched-mode supplies. If the downstream load includes any rectified or switched electronics, a Type A or Type B RC unit would be the correct choice; this Type AC is for purely resistive or inductive AC circuits without electronic front-ends.","metaTitle":"Siemens SENTRON 5SM9422-0KK RC Unit, 2-Pole, 40 A, 100 mA, 2","metaDescription":"Siemens SENTRON 5SM9422-0KK RC unit, 2-pole, type AC, 40 A rated, 100 mA trip, 230/400 VAC. Current lifecycle stage. Quoted to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Residual Current Breakers (RCCB/RCBO)"],"specifications":{"title":"5SM9422-0KK","description":"RC unit, 2-pole, type AC, In: 40 A, 100 mA, Un AC: 400 V","Number Of Poles":"2","lifecycle_stage":"current","at AC rated value":"40 A","Product Brand Name":"SENTRON","Product Designation":"RC unit electronic","Design Of The Product":"Instantaneous","Residual Current Type":"AC","at 40 °C rated value":"37.2 A","at 45 °C rated value":"37.2 A","at 50 °C rated value":"36 A","at 55 °C rated value":"34.8 A","at 60 °C rated value":"34 A","at 65 °C rated value":"33.2 A","at 70 °C rated value":"32 A","Tripping Fault Current Rated Value":"100 mA","value range of the supply voltage at AC":"230/400 V","Value Range Of The Supply Voltage Frequency":"50 Hz","for rated value of the current at AC in hot operating state per pole":"0.8 W"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/1aebaebd187164b30a28cdc436977676.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=629199&mlfb=5SM9422-0KK"},"ai":{"faq":[{"question":"What are the key ratings for the 5SM9422-0KK?","answer":"It is a 2-pole, type AC residual current unit rated 40 A at 40 °C with a 100 mA tripping fault current, for 230/400 VAC, 50 Hz networks."},{"question":"Where can I buy the 5SM9422-0KK?","answer":"This part is sourced and quoted to order against an RFQ through independent distribution channels; availability and current pricing are confirmed at the time of quote."},{"question":"Will the 5SM9422-0KK drop into a panel specified around a 5SL4363-7 without rewiring?","answer":"No — the 5SL4363-7 is a 3-pole miniature circuit breaker (MCB) with a different function and footprint. The 5SM9422-0KK is a 2-pole RC unit; it occupies a different DIN-rail position and serves a different protective role (residual current vs overcurrent). They are not drop-in interchangeable."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SM9422-0KK","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/5SM9422-0KK 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}}