{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RW4028-2BB04","brand":"Siemens","brandSlug":"siemens","productSlug":"3RW4028-2BB04","canonicalUrl":"https://aoctrl.com/siemens/3RW4028-2BB04","factsUrl":"https://aoctrl.com/api/mcp/products/3RW4028-2BB04","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RW4028-2BB04 soft starter, S0 frame, 38 A at 40 °C, 600 V insulation, integrated bypass, spring-loaded terminals, screw and snap-on DIN-rail mounting.","salesMarkdown":"## Rated current and thermal derating in the panel The 3RW4028-2BB04: The derating curve matters when the soft starter shares a crowded enclosure with other heat sources — the S0 frame's natural convection relies on the 60 mm upward and 40 mm downward clearance. The integrated bypass contact system switches the thyristors out of the circuit once the motor reaches full speed, cutting heat dissipation during run. This lets the unit handle the rated current without external bypass contactor wiring. ## Mounting and wiring for the S0 frame Screw and snap-on mounting to DIN rail — the snap-on feature lets you seat the unit without tools; the screw secures it against vibration. The S0 frame footprint is 45 mm wide by 150 mm high by 155 mm deep. No screwdriver needed for termination; the spring cage holds the conductor under vibration. ## Motor protection and adjustable current limitation Built-in motor overload protection and intrinsic device protection cover the soft starter's own thyristors against overtemperature and overcurrent. The adjustable current limitation lets you set the start ramp peak current as a percentage of the motor FLA — minimum load is 20 %. An external reset input allows remote fault reset from a PLC or pushbutton panel, keeping the starter in the loop without a manual walk to the cabinet.","metaTitle":"Siemens 3RW4028-2BB04 SIRIUS Soft Starter, 38 A, 600 V","metaDescription":"Siemens 3RW4028-2BB04 SIRIUS soft starter, 38 A at 40 °C, 600 V insulation, S0 frame, integrated bypass. Active production. Quoted to order.","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":"3RW4028-2BB04","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","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":"No","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":"-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":"$400.05","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/96e0ab6fa75c822890130253c8175906.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=138970&mlfb=3RW4028-2BB04"},"ai":{"faq":[{"question":"What is the rated current of the 3RW4028-2BB04 at different ambient temperatures?","answer":"The derating follows the natural convection limits of the S0 frame."},{"question":"Does the 3RW4028-2BB04 include an integrated bypass contactor?","answer":"Yes, the integrated bypass contact system shorts the thyristors after the motor reaches full speed, eliminating the need for an external bypass contactor and reducing heat in the panel during run."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RW4028-2BB04","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/3RW4028-2BB04 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}}