{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RB2025-2NB0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RB2025-2NB0","canonicalUrl":"https://aoctrl.com/siemens/3RB2025-2NB0","factsUrl":"https://aoctrl.com/api/mcp/products/3RB2025-2NB0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RB2025-2NB0 solid-state overload relay, CLASS 20E, 690 V AC-3 rated, ATEX Ex II (2) GD, IP20 front, contactor mounting.","salesMarkdown":"The Siemens 3RB2025-2NB0 is a SIRIUS solid-state overload relay — no bimetals, no heater packs to swap. It protects motors against overload and phase loss by monitoring current through the main circuit and tripping a CLASS 20E curve. That trip class means it allows a 20-second overload at 7.2× FLA before opening, which matches standard NEMA-design motors and most IEC general-purpose induction motors on pumps, fans, and conveyors. The front panel carries IP20 protection — safe for enclosed panels, but not for washdown areas. Mounts directly onto a contactor (contactor mounting), saving DIN rail space in a crowded enclosure. Screw-type terminals on the main circuit accept 0.5 to 4 mm² solid or 2× 0.5 to 2.5 mm² stranded — standard panel wire sizes for motor circuits up to this class. ## Where it goes and what it guards This relay lives inside a motor control center or a standalone panel, snapped onto the contactor. It's sized for a 45 mm wide footprint, 73 mm tall, 75 mm deep — fits standard 45 mm contactor profiles across the SIRIUS family. The ATEX approval (PTB 06 ATEX 3001 Ex II (2) GD) means it can be used in the safe-area side of a motor starter that feeds equipment in a Zone 1 or Zone 2 gas or dust atmosphere — the relay itself sits outside the hazardous area but is certified for the associated apparatus role. Storage and transport range of -40 to +80 °C handles cold warehouses and hot shipping containers without issue. CLASS 20E is the trip curve — it's the standard for most general-purpose motor protection. If your motor starter was designed around a CLASS 10 or CLASS 30 relay, this one will trip at a different speed during a stall. CLASS 20 is the middle ground: slower than CLASS 10 (which protects short-time-rated motors) and faster than CLASS 30 (for high-inertia loads like centrifuges). For a standard pump or fan motor, CLASS 20 is what you want. No derating worries on a 400 V or 480 V line. Shock resistance of 15g for 11 ms means it survives the mechanical slam of a contactor closing and the vibration of a running motor starter.","metaTitle":"Siemens 3RB2025-2NB0 SIRIUS Solid-State Overload Relay, CLAS","metaDescription":"Siemens 3RB2025-2NB0 SIRIUS solid-state overload relay, CLASS 20E trip class, 690 V AC-3 max, ATEX Ex II (2) GD, IP20 front, contactor mounting. Active production. Sourced to order","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Overload Relays"],"specifications":{"Depth":"75 mm","Solid":"0.5 ... 4 mm², 2x (0.5 ... 2.5 mm²)","Width":"45 mm","Height":"73 mm","Maximum":"2 000 m","Upwards":"0 mm","at 24 V":"2 A","at 60 V":"0.55 A","Forwards":"0 mm","at 110 V":"0.3 A","at 120 V":"4 A","at 125 V":"0.3 A","at 220 V":"0.11 A","at 230 V":"3 A","Backwards":"0 mm","Downwards":"0 mm","Trip class":"CLASS 20E","At The Side":"6 mm","On The Front":"IP20","Mounting type":"Contactor mounting","During Storage":"-40 ... +80 °C","lifecycle_stage":"current","During Operation":"-25 ... +60 °C","During Transport":"-40 ... +80 °C","Shock resistance":"15g / 11 ms","Mounting position":"any","Product brand name":"SIRIUS","Type of protection":"PTB 06 ATEX 3001 Ex II (2) GD","Product designation":"solid-state overload relay","For Auxiliary Contacts":"0","For Main Current Circuit":"screw-type terminals","at AC-3 rated value maximum":"690 V","at AC in hot operating state":"0.05 W","Relative humidity during operation":"100 %","due to burst acc. to IEC 61000-4-4":"2 kV (power ports), 1 kV (signal ports) corresponds to degree of severity 3","at AWG conductors for main contacts":"2x (14 ... 10)","Surge voltage resistance rated value":"6 kV","Reference code acc. to DIN EN 81346-2":"F","at AC in hot operating state per pole":"0.02 W","With Degree Of Pollution 3 Rated Value":"690 V","Finely Stranded With Core End Processing":"0.5 ... 2.5 mm², 2x (0.5 ... 1.5 mm²)","Number of poles for main current circuit":"3","at AWG conductors for auxiliary contacts":"2x (20 ... 14)","For Auxiliary And Control Current Circuit":"screw-type terminals","Number of NC contacts for auxiliary contacts":"1","Number of NO contacts for auxiliary contacts":"1","Electrostatic discharge acc. to IEC 61000-4-2":"6 kV contact discharge / 8 kV air discharge","Size of contactor can be combined company-specific":"S0","due to conductor-earth surge acc. to IEC 61000-4-5":"2 kV (line to earth) corresponds to degree of severity 3","Removable Terminal For Auxiliary And Control Circuit":"Yes","For Short-Circuit Protection Of The Auxiliary Switch Required":"fuse gL/gG: 6 A","Adjustable pick-up value current of the current-dependent overload release":"0.32 ... 1.25 A"}},"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=165275&mlfb=3RB2025-2NB0","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RB2025-2NB0/alternatives.json"},"ai":{"faq":[{"question":"What trip class is this overload relay?","answer":"CLASS 20E. That means it will trip after approximately 20 seconds at 7.2× the set current. This is the standard trip class for general-purpose NEMA and IEC motors driving pumps, fans, and conveyors."},{"question":"What wire sizes does it accept?","answer":"Screw terminals accept 0.5 to 4 mm² solid wire, or 2× 0.5 to 2.5 mm² stranded. For AWG, that's 2× 14 to 10 AWG on the main circuit."},{"question":"Does this relay have ATEX certification?","answer":"Yes. It carries PTB 06 ATEX 3001 Ex II (2) GD approval, meaning it is certified as associated apparatus for use with equipment in Zone 1/2 gas and Zone 21/22 dust atmospheres."},{"question":"How does it mount?","answer":"It mounts directly onto a contactor (contactor mounting). No DIN rail needed. The 45 mm width matches standard SIRIUS contactor profiles."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RB2025-2NB0","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/3RB2025-2NB0 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}}