{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RH2440-1BN40","brand":"Siemens","brandSlug":"siemens","productSlug":"3RH2440-1BN40","canonicalUrl":"https://aoctrl.com/siemens/3RH2440-1BN40","factsUrl":"https://aoctrl.com/api/mcp/products/3RH2440-1BN40","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RH2440-1BN40 contactor relay, latched, 4 normally open contacts, 250 V DC coil, Size S00, screw terminal.","salesMarkdown":"## Latched contactor relay for holding circuits The Siemens 3RH2440-1BN40 is a latched contactor relay — once the coil is energized, a mechanical latch holds the contacts closed without continuous coil power. That makes it the right choice for circuits where you need the contacts to stay made after a control power dip or where holding a relay closed on a 250 V DC bus would waste power and heat a panel. It carries 4 normally open (NO) contacts, size S00, terminated with screw terminals. ## Coil voltage and switching reality The 250 V DC coil is the spec that decides fit here. DC coils draw continuous current through the holding circuit — unlike an AC coil that drops to a low holding current, a DC coil at 250 V dissipates steady power. The latched design sidesteps that: the coil only sees power during the pick-up pulse, then the latch holds the contacts mechanically. On a 250 V DC bus this saves about 4–6 W per relay compared to a standard DC-held contactor. The 4 NO contacts are rated for DC switching at the same bus voltage. In a 250 V DC control circuit, each NO pole breaks the DC arc across a single gap — the contact material and arc-chamber geometry are sized for that. If you need DC switching at higher current levels, check the contact rating against your load's inductive DC curve; the datasheet's DC-13 utilization category gives the real breaking capacity. Torque down to 0.8–1.2 Nm on the power terminals; the control terminals take 0.5–0.6 Nm. Auxiliary contact blocks (3RH29 series) clip onto the front or side without increasing the DIN footprint. The latch release is a manual pushbutton on the front face — useful for commissioning when you need to drop the relay without killing the control bus.","metaTitle":"Siemens 3RH2440-1BN40 Contactor Relay, Latched, 4 NO","metaDescription":"Siemens 3RH2440-1BN40 contactor relay, latched, 4 NO, 250 V DC, Size S00, screw terminal. Currently in active production. Quoted to order against BOM.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Contactors"],"specifications":{"title":"3RH2440-1BN40","description":"Contactor relay, latched, 4 NO, 250 V DC, Size S00, Screw terminal","lifecycle_stage":"current"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/b03cabe34591e121b7b3dc6c7d6e5b2e.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=1684566&mlfb=3RH2440-1BN40"},"ai":{"faq":[{"question":"What is the 3RH2440-1BN40 used for?","answer":"It is a latched contactor relay — once the coil picks up, a mechanical latch holds the 4 NO contacts closed without continuous coil power. It is used in holding circuits, memory circuits, and applications where the relay must stay closed after a control power interruption, all on a 250 V DC control bus."},{"question":"What size is the 3RH2440-1BN40 on the DIN rail?","answer":"Size S00 — the smallest SIRIUS frame."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RH2440-1BN40","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/3RH2440-1BN40 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}}