{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RB2143-4UB0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RB2143-4UB0","canonicalUrl":"https://aoctrl.com/siemens/3RB2143-4UB0","factsUrl":"https://aoctrl.com/api/mcp/products/3RB2143-4UB0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RB2143-4UB0, solid-state overload relay, 3-pole, screw-type terminals, adjustable trip Class 5E/10E/20E/30E, ATEX Ex II (2) GD, 124 mm depth.","salesMarkdown":"The Siemens 3RB2143-4UB0 is a SIRIUS solid-state overload relay — a 3-pole device that protects motor circuits against overload and phase failure without the mechanical wear of a bimetallic strip. It mounts directly onto a contactor (contactor mounting, per the spec), so the whole motor starter package stays compact on the DIN rail. The trip class is adjustable across four settings — CLASS 5E, 10E, 20E and 30E — which means you can tailor the tripping time to the starting characteristic of the load: fast for a pump that starts unloaded, slower for a high-inertia fan or conveyor. The auxiliary contact ratings cover a wide control-voltage range: 2 A at 24 V, 4 A at 120 V, 3 A at 230 V, and 0.55 A at 60 V, among others. That means the same relay works in a 24 VDC PLC-controlled cabinet or a 230 VAC relay-logic panel without swapping out the aux block. The main-circuit terminals accept solid wire from 0.5 to 4 mm² (or 2x 0.5 to 2.5 mm²) and stranded up to 70 mm² — sized for motor feeders up to roughly the 50-60 A range, depending on the contactor frame. It handles 100 % relative humidity during operation — no derating needed for condensing environments inside a non-heated enclosure. Shock resistance is rated at 15g / 11 ms, which covers most industrial vibration profiles without needing a separate shock mount. The relay fastens directly to the contactor (contactor mounting), saving a DIN-rail slot. Dimensions: 70 mm wide, 106 mm tall, 124 mm deep. Clearances: 0 mm upwards, forwards, and backwards; 6 mm at the side. That tight clearance means you can pack starters side-by-side without extra spacing, as long as the side gap is respected. The ATEX approval (PTB 06 ATEX 3001 Ex II (2) GD) allows installation in Zone 2 gas and Zone 22 dust atmospheres — relevant for chemical or grain-handling lines where a standard overload would be a non-starter.","metaTitle":"Siemens 3RB2143-4UB0 SIRIUS solid-state overload relay, adju","metaDescription":"Siemens 3RB2143-4UB0 SIRIUS solid-state overload relay, 3-pole, screw terminals, adjustable trip Class 5E/10E/20E/30E, ATEX Ex II (2) GD, 124 mm depth. Active production. RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Overload Relays"],"specifications":{"Depth":"124 mm","Solid":"0.5 ... 4 mm², 2x (0.5 ... 2.5 mm²)","Width":"70 mm","Height":"106 mm","Upwards":"0 mm","at 24 V":"2 A","at 60 V":"0.55 A","Forwards":"0 mm","Per Pole":"0.02 W","Stranded":"2x (10 ... 50 mm²), 10 ... 70 mm²","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 5E, 10E, 20E and 30E adjustable","At The Side":"6 mm","During Storage":"-40 ... +80 °C","lifecycle_stage":"current","During Operation":"-25 ... +60 °C","During Transport":"-40 ... +80 °C","Fastening Method":"Contactor mounting","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 Main Current Circuit":"screw-type terminals","Substance Prohibitance (Date)":"07/01/2006","at AWG cables for main contacts":"2x (10 ... 1/0), 1x (10 ... 2/0)","For Auxiliary And Control Circuit":"screw-type terminals","Relative Humidity During Operation":"100 %","Surge Voltage Resistance Rated Value":"8 kV","at AWG cables for auxiliary contacts":"2x (20 ... 14)","due to burst according to IEC 61000-4-4":"2 kV (power ports), 1 kV (signal ports) corresponds to degree of severity 3","reference code according to IEC 81346-2":"F","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","number of CO contacts for auxiliary contacts":"0","number of NC contacts for auxiliary contacts":"1","number of NO contacts for auxiliary contacts":"1","Size Of Contactor Can Be Combined Company-Specific":"S3","electrostatic discharge according to IEC 61000-4-2":"6 kV contact discharge / 8 kV air discharge","Installation Altitude At Height Above Sea Level Maximum":"2 000 m","For Short-Circuit Protection Of The Auxiliary Switch Required":"fuse gL/gG: 6 A","insulation voltage with degree of pollution 3 at AC rated value":"1 000 V","Product Component Removable Terminal For Auxiliary And Control Circuit":"Yes","power loss [W] for rated value of the current at AC in hot operating state":"0.05 W","Adjustable Current Response Value Current Of The Current-Dependent Overload Release":"12.5 ... 50 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=437046&mlfb=3RB2143-4UB0","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RB2143-4UB0/alternatives.json"},"ai":{"faq":[{"question":"What trip classes can this relay be set to?","answer":"The trip class is adjustable to CLASS 5E, 10E, 20E, or 30E. Class 10E is the standard motor-protection setting for most general-purpose induction motors; class 20E or 30E accommodates high-inertia loads like large fans or centrifuges that take longer to start."},{"question":"What approvals does this overload relay carry?","answer":"It carries ATEX certification PTB 06 ATEX 3001 Ex II (2) GD for use in potentially explosive gas and dust atmospheres (Zone 2 gas, Zone 22 dust). The surge voltage resistance is rated at 8 kV, and it meets IEC 61000-4-4 burst immunity at severity level 3 (2 kV on power ports, 1 kV on signal ports)."},{"question":"What wire sizes does the 3RB2143-4UB0 accept?","answer":"Main-circuit screw terminals accept solid wire 0.5... 4 mm² (or 2x 0.5... 2.5 mm²), stranded 10... 70 mm², and AWG 2x (10... 1/0) or 1x (10... 2/0). Auxiliary/control terminals accept solid 0.5... 2.5 mm² (2x 0.5... 1.5 mm²) and AWG 2x (20... 14). Finely stranded wire with ferrule is also supported: 0.5... 2.5 mm², 2x 0.5... 1.5 mm²."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RB2143-4UB0","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/3RB2143-4UB0 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}}