{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RW4028-2TB04","brand":"Siemens","brandSlug":"siemens","productSlug":"3RW4028-2TB04","canonicalUrl":"https://aoctrl.com/siemens/3RW4028-2TB04","factsUrl":"https://aoctrl.com/api/mcp/products/3RW4028-2TB04","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RW4028-2TB04 soft starter, Size S0, 38 A at 40 °C, 600 V insulation voltage, 50/60 Hz, 24 V AC/DC control, spring-loaded terminals, integrated bypass contact system.","salesMarkdown":"## Sizing against the thermal envelope The 3RW4028-2TB04: That derating starts at 40 °C, so if your enclosure runs hotter than that — common with drives or transformers sharing the cabinet — size the bypass rating for the 60 °C figure, not the 40 °C headline. The integrated bypass contact system means once the motor is at speed, the thyristors are shorted out — no continuous heat dissipation from the power semiconductors, just the bypass contact resistance. ## Termination and panel fit Main current circuit and auxiliary/control circuits both use spring-loaded terminals — no screw torque to check, no re-torquing after thermal cycling. The main circuit accepts 2x (16... 10) plus 1x 8 AWG; auxiliary side takes 2x (24... 14) AWG. Mounting is screw or snap-on onto DIN rail, Size S0 footprint: 45 mm wide, 150 mm tall, 155 mm deep. Clearance needs: 60 mm above, 40 mm below, 15 mm at the sides. Mounting position matters — with the optional fan the unit can rotate ±90° on a vertical surface or tilt ±22.5° front/back; without the fan, rotation is limited to ±10°. ## Protection and control logic Built-in motor overload protection and intrinsic device protection cover the soft starter itself and the downstream motor — no separate overload relay needed for most applications. Adjustable current limitation lets you set the starting current between 20 % and 100 % of the rated current — useful for gentle starts on pumps or conveyors where mechanical shock is the concern. External reset input and a red fault signal LED give the panel operator a clear indication and remote reset capability without opening the enclosure.","metaTitle":"Siemens 3RW4028-2TB04 SIRIUS Soft Starter, 38 A, 600 V","metaDescription":"Siemens 3RW4028-2TB04 SIRIUS soft starter, 38 A at 40 °C, 600 V insulation, size S0. Active production; quoted to order. Integrated bypass, spring terminals.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Soft Starters"],"specifications":{"Depth":"155mm","Solid":"2x (0.25 ... 2.5 mm²)","Width":"45mm","title":"3RW4028-2TB04","Height":"150mm","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 spring-type 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%","For Main Contacts":"16 ... 10, 1x 8","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 (24 ... 14)","For Main Current Circuit":"spring-loaded 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":"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":"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%","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":"-20%","relative negative tolerance of the control supply voltage at AC at 60 Hz":"-20%","relative positive tolerance of the control supply voltage at AC at 50 Hz":"20%","relative positive tolerance of the control supply voltage at AC at 60 Hz":"20%","Adjustable Motor Current For Motor Overload Protection Minimum Rated Value":"23A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/a7bed232f99738ec7420718e2e5480ee.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=316322&mlfb=3RW4028-2TB04"},"ai":{"faq":[{"question":"How do I get current pricing and availability for 3RW4028-2TB04?","answer":"Submit an RFQ through this listing. No stock-holding claim — availability is verified per request."},{"question":"Does the 3RW4028-2TB04 have an integrated bypass?","answer":"Yes — the integrated bypass contact system shorts the thyristors after start, eliminating continuous heat dissipation from the power semiconductors. This means the 38 A rating at 40 °C applies to the bypass, not just the starting duty."},{"question":"What compliance documentation does Siemens provide for 3RW4028-2TB04?","answer":"The unit carries a pollution degree of 3 per IEC 60947-4-2, which covers industrial environments with conductive pollution. Insulation voltage is rated 600 V. Siemens provides the standard CE declaration of conformity and IEC/UL certifications — request specific documentation at RFQ time."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RW4028-2TB04","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/3RW4028-2TB04 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-22T19:47:38.189Z","lastPublished":"2026-07-22T19:47:38.189Z","indexable":true}}