{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RW4028-1TB04","brand":"Siemens","brandSlug":"siemens","productSlug":"3RW4028-1TB04","canonicalUrl":"https://aoctrl.com/siemens/3RW4028-1TB04","factsUrl":"https://aoctrl.com/api/mcp/products/3RW4028-1TB04","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RW4028-1TB04 soft starter, 38 A at 40 °C, 24 V control, S0 frame, 45 mm width, screw and snap-on mounting.","salesMarkdown":"The Siemens 3RW4028-1TB04 is a SIRIUS soft starter in the S0 frame size, designed to ramp three-phase induction motors up to 38 A at 40 °C (34 A at 50 °C, 31 A at 60 °C) on a 400 V line. It's a current-production part — no lifecycle concerns for a new BOM line. The 45 mm width and screw/snap-on mounting mean it drops into a standard DIN-rail panel without extra bracketry, and the integrated bypass contact system pulls the thyristors out of the circuit once the motor is at speed, so you're not dissipating heat from the semiconductors during continuous run. The S0 frame keeps the footprint compact — 45 mm wide, 125 mm high, 155 mm deep — and the 60 mm upward / 40 mm downward / 15 mm side clearance leaves room for adjacent devices in a dense panel. Above that, derate to 34 A at 50 °C and 31 A at 60 °C. The 20 % minimum load means it won't regulate properly below that motor current, so it's not a fit for fractional-horsepower motors. The 600 V rated insulation voltage (pollution degree 3 per IEC 60947-4-2) covers 400 V and 480 V systems with margin. Control voltage is 24 V AC/DC at 50/60 Hz. The auxiliary contacts accept 2x conductors from 20 to 14 AWG. The main power terminals accept 2x solid conductors from 0.5 to 2.5 mm². Maximum wire length to the motor is 300 m — keep that in mind for remote installations.","metaTitle":"Siemens 3RW4028-1TB04 SIRIUS Soft Starter, 38 A, 45 mm","metaDescription":"Siemens 3RW4028-1TB04 SIRIUS soft starter, 38 A at 40 °C, S0 frame, 45 mm wide. Active production. Screw and snap-on mounting. Integrated bypass. RFQ for pricing.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Soft Starters"],"specifications":{"Depth":"155mm","Solid":"2x (0.5 ... 2.5 mm²)","Width":"45mm","title":"3RW4028-1TB04","Height":"125mm","Upwards":"60mm","Downwards":"40mm","Thyristors":"Yes","At The Side":"15mm","description":"SIRIUS soft starter S0 38 A, 18.5 kW/400 V, 40 °C 200-480 V AC, 24 V AC/DC Screw terminals Thermistor motor protection","During Storage":"-40 ... +80°C","External Reset":"Yes","lifecycle_stage":"current","During Operation":"-25 ... +60°C","Fastening Method":"screw and snap-on mounting","Minimum Load [%]":"20%","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":"24V","at 60 Hz rated value":"24V","at 40 °C rated value":"38A","at 50 °C rated value":"34A","at 60 °C rated value":"31A","For Auxiliary Contacts":"2x (20 ... 14)","For Main Current Circuit":"screw-type terminals","Motor Overload Protection":"Yes","Intrinsic Device Protection":"Yes","Adjustable Current Limitation":"Yes","Size Of Engine Control Device":"S0","Insulation Voltage Rated Value":"600V","Using The Front Clamping Point":"1x 8, 2x (16 ... 10)","Operating Frequency Rated Value":"50 ... 60Hz","Display Version For Fault Signal":"red","Integrated Bypass Contact System":"Yes","For Auxiliary And Control Circuit":"screw-type 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 (0.5 ... 1.5 mm²)","Number Of Poles For Main Current Circuit":"3","Evaluation Of Thermistor Motor Protection":"Yes","at standard circuit at 40 °C rated value":"18.5kW","at standard circuit at 50 °C rated value":"25hp","control supply voltage 1 at DC rated value":"24V","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/DC","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":"200 ... 480V","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%","For Auxiliary Contacts Finely Stranded With Core End Processing":"2x (20 ... 16)","relative negative tolerance of the control supply voltage at DC":"-20%","relative positive tolerance of the control supply voltage at DC":"20%","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":"19W","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":"23A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$477.52 – $626.00","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/85e8ea7da5e846a7fc0f3c38f8a9199b.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=426846&mlfb=3RW4028-1TB04"},"ai":{"faq":[{"question":"What are the key ratings for this soft starter?","answer":"Rated 38 A at 40 °C, 34 A at 50 °C, 31 A at 60 °C. Control voltage 24 V AC/DC. Insulation voltage 600 V. Minimum load 20 %. Integrated bypass. S0 frame, 45 mm wide."},{"question":"Does it have an integrated bypass?","answer":"Yes, the integrated bypass contact system engages once the motor reaches speed, taking the thyristors out of the circuit to reduce heat dissipation."},{"question":"What mounting options does it support?","answer":"Screw and snap-on mounting onto a 35 mm DIN rail. With an additional fan, it can be rotated ±90° on a vertical surface; without the fan, rotation is limited to ±10°."},{"question":"What is the maximum wire length to the motor?","answer":"300 m."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RW4028-1TB04","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/3RW4028-1TB04 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}}