{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RW4075-2BB45","brand":"Siemens","brandSlug":"siemens","productSlug":"3RW4075-2BB45","canonicalUrl":"https://aoctrl.com/siemens/3RW4075-2BB45","factsUrl":"https://aoctrl.com/api/mcp/products/3RW4075-2BB45","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RW4075-2BB45 soft starter, Size S12, 356 A at 40 °C, 600 V insulation, 50/60 Hz, thyristor-based, screw fixing mount.","salesMarkdown":"## 356 A at 40 °C — the continuous current that matters The 3RW4075-2BB45: That 356 A is the continuous motor current it can handle without derating — above 40 °C the current drops to 315 A at 50 °C and 280 A at 60 °C, so the real-world ceiling depends on your enclosure's internal temperature. Thyristor-based design with adjustable current limitation — you set the inrush ceiling as a percentage of the motor FLA, which is the primary knob for controlling start torque and supply dip. ## Mounting and wiring — screw-fixed, busbar-ready This is a screw-fixing mount, not DIN rail — it bolts to the backplate with the Size S12 footprint (278 mm deep, 160 mm wide, 230 mm tall). The mounting position allows vertical surface installation with ±90° rotation and ±22.5° tilt front/back when using the optional fan; without the fan the tilt range narrows to ±10°. Main circuit termination accepts stranded cable 70–240 mm² or 2/0–500 kcmil, with busbar connection via front, back, or both clamping points. The max motor cable length is 300 m, which is adequate for most motor centers but may need an output reactor beyond that. ## Environmental and protection ratings Pollution degree 3 per IEC 60947-4-2 — rated for industrial environments where conductive dust or condensation is present. Operating temperature range -25 to +60 °C, storage -40 to +80 °C, so it can sit in an unheated warehouse or a hot panel without issue. Derating begins at 40 °C; above that, the current must be reduced per the derating curve. Minimum load is 20% of the rated current — below that the thyristor firing may not be reliable, so don't use it on a motor that's oversized relative to the load. Not configurable for inside-delta wiring; this is an in-line soft starter only.","metaTitle":"Siemens 3RW4075-2BB45 SIRIUS Soft Starter, 356 A, Size S12","metaDescription":"Siemens 3RW4075-2BB45 SIRIUS soft starter, 356 A at 40°C, 600 V insulation, Size S12. Active production, quoted to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Soft Starters"],"specifications":{"Depth":"278mm","Solid":"2x (0.25 ... 1.5 mm²)","Width":"160mm","title":"3RW4075-2BB45","Height":"230mm","Upwards":"100mm","Stranded":"70 ... 240 mm²","Downwards":"75mm","Thyristors":"Yes","At The Side":"5mm","description":"SIRIUS soft starter S12 356 A, 250 kW/500 V, 40 °C 400-600 V AC, 230 V AC spring-type terminals!!! Phased-out product!!! Successor is SIRIUS 3RW5, Preferred successor type is >>3RW5075-2AB15<<","During Storage":"-40 ... +80°C","External Reset":"Yes","Finely Stranded":"50 ... 240 mm²","lifecycle_stage":"current","During Operation":"-25 ... +60°C","Fastening Method":"screw fixing","Minimum Load [%]":"20%","For Main Contacts":"2/0 ... 500 kcmil","Mounting Position":"With additional fan: With vertical mounting surface +/-90° rotatable, with vertical mounting surface +/- 22.5° tiltable to the front and back Without additional fan: With vertical mounting surface +/-10° rotatable, with vertical mounting surface +/- 10° t","Product Brand Name":"SIRIUS","Degree Of Pollution":"3, acc. to IEC 60947-4-2","Product Designation":"Soft starter","Wire Length Maximum":"300m","Derating Temperature":"40°C","Inside-Delta Circuit":"No","at 50 Hz rated value":"230V","at 60 Hz rated value":"230V","at 40 °C rated value":"356A","at 50 °C rated value":"315A","at 60 °C rated value":"280A","For Auxiliary Contacts":"2x (24 ... 16)","For Main Current Circuit":"busbar connection","Motor Overload Protection":"Yes","Using Both Clamping Points":"min. 2x 2/0, max. 2x 500 kcmil","Intrinsic Device Protection":"Yes","Adjustable Current Limitation":"Yes","Size Of Engine Control Device":"S12","Using The Back Clamping Point":"250 ... 500 kcmil","Insulation Voltage Rated Value":"600V","Using The Front Clamping Point":"3/0 ... 600 kcmil","Operating Frequency Rated Value":"50 ... 60Hz","Display Version For Fault Signal":"red","Integrated Bypass Contact System":"Yes","For Auxiliary And Control Circuit":"spring-loaded terminals","Product Component Motor Brake Output":"No","during storage according to IEC 60721":"1K6 (only occasional condensation), 1C2 (no salt mist), 1S2 (sand must not get inside the devices), 1M4","reference code according to EN 61346-2":"Q","during operation according to IEC 60721":"3K6 (no formation of ice, no condensation), 3C3 (no salt mist), 3S2 (sand must not get into the devices), 3M6","during transport according to IEC 60721":"2K2, 2C1, 2S1, 2M2 (max. fall height 0.3 m)","Finely Stranded With Core End Processing":"2x (0.25 ... 1.5 mm²)","Number Of Poles For Main Current Circuit":"3","Evaluation Of Thermistor Motor Protection":"No","at standard circuit at 40 °C rated value":"250kW","at standard circuit at 50 °C rated value":"300hp","Finely Stranded Without Core End Processing":"min. 2x 50 mm², max. 2x 185 mm²","number of CO contacts for auxiliary contacts":"1","number of NC contacts for auxiliary contacts":"0","number of NO contacts for auxiliary contacts":"2","Type Of Voltage Of The Control Supply Voltage":"AC","Control Supply Voltage Frequency 1 Rated Value":"50Hz","Control Supply Voltage Frequency 2 Rated Value":"60Hz","Installation Altitude At Height Above Sea Level":"5 000m","continuous operating current [% of Ie] at 40 °C":"115%","Operating Voltage At Standard Circuit Rated Value":"400 ... 600V","contact rating of auxiliary contacts according to UL":"B300 / R300","Relative Negative Tolerance Of The Operating Frequency":"-10%","Relative Positive Tolerance Of The Operating Frequency":"10%","Relative Negative Tolerance Of The Control Supply Voltage Frequency":"-10%","Relative Positive Tolerance Of The Control Supply Voltage Frequency":"10%","Relative Negative Tolerance Of The Operating Voltage At Standard Circuit":"-15%","Relative Positive Tolerance Of The Operating Voltage At Standard Circuit":"10%","power loss [W] at operational current at 40 °C during operation typical":"125W","relative negative tolerance of the control supply voltage at AC at 50 Hz":"-15%","relative negative tolerance of the control supply voltage at AC at 60 Hz":"-15%","relative positive tolerance of the control supply voltage at AC at 50 Hz":"10%","relative positive tolerance of the control supply voltage at AC at 60 Hz":"10%","Adjustable Motor Current For Motor Overload Protection Minimum Rated Value":"131A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/fe3c68365e1a318c89f433514fe1051b.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=33271&mlfb=3RW4075-2BB45"},"ai":{"faq":[{"question":"What is the continuous current rating of 3RW4075-2BB45 at different temperatures?","answer":"356 A at 40 °C, 315 A at 50 °C, and 280 A at 60 °C. The derating starts above 40 °C ambient, so the actual continuous current depends on your enclosure's internal temperature."},{"question":"What wire sizes does 3RW4075-2BB45 accept for main power and control?","answer":"Main circuit accepts stranded 70–240 mm² or 2/0–500 kcmil cable, with busbar connection options."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RW4075-2BB45","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/3RW4075-2BB45 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}}