{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RW4028-1BB05","brand":"Siemens","brandSlug":"siemens","productSlug":"3RW4028-1BB05","canonicalUrl":"https://aoctrl.com/siemens/3RW4028-1BB05","factsUrl":"https://aoctrl.com/api/mcp/products/3RW4028-1BB05","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RW4028-1BB05 soft starter, 38 A at 40 °C, size S0, screw and snap-on mounting, integrated bypass.","salesMarkdown":"The Siemens 3RW4028-1BB05 is a SIRIUS soft starter, size S0, rated 38 A at 40 °C. It uses thyristors to ramp motor voltage during start, reducing inrush current and mechanical stress on the load. The integrated bypass contact system bridges the thyristors once the motor is at full speed, eliminating heat dissipation from the semiconductors during run — that's the main reason this size S0 frame can handle 38 A continuously without an external heatsink. The 38 A rating at 40 °C is the baseline; at 50 °C it derates to 34 A, and at 60 °C to 31 A. The minimum load is 20 % of the rated current, so it won't regulate properly on a motor drawing less than about 7.6 A. Insulation voltage is rated 600 V, and the operating frequency covers 50 to 60 Hz. The S0 footprint is 45 mm wide, 125 mm tall, 155 mm deep. Clearance: 60 mm above, 40 mm below, 15 mm to the side. With an additional fan, the mounting surface can be vertical and rotated up to ±90° or tilted ±22.5° front/back. Without a fan, keep it within ±10° rotation and ±10° tilt. Main circuit and auxiliary/control connections are screw-type terminals; the main circuit accepts 2x (0.5... 2.5 mm²) solid or stranded. Maximum motor cable length is 300 m. ## Protection and control features Built-in motor overload protection and intrinsic device protection are standard. The adjustable current limitation lets you set the start current between the minimum load and the device's rated current — useful for matching the soft starter to the actual motor FLA without changing hardware. An external reset input is provided, and a red fault signal display is on the front. The control circuit is 24 V AC/DC (both 50 and 60 Hz). No internal delta circuit or motor brake output on this variant.","metaTitle":"Siemens 3RW4028-1BB05 SIRIUS Soft Starter, 38A, Size S0","metaDescription":"Siemens 3RW4028-1BB05 SIRIUS soft starter, 38A at 40°C, size S0, integrated bypass, adjustable current limitation, screw and snap-on mounting. Active production.","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":"3RW4028-1BB05","Height":"125mm","Upwards":"60mm","Downwards":"40mm","Thyristors":"Yes","At The Side":"15mm","description":"SIRIUS soft starter S0 38 A, 22 kW/500 V, 40 °C 400-600 V AC, 24 V AC/DC Screw 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%","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":"No","at standard circuit at 40 °C rated value":"22kW","at standard circuit at 50 °C rated value":"30hp","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":"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%","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":"$647.00","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/6eba852ea4929d93e8bb5df26c4f3dbf.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=469902&mlfb=3RW4028-1BB05"},"ai":{"faq":[{"question":"What are the key ratings for this soft starter?","answer":"Rated 38 A at 40 °C, size S0, 600 V insulation voltage, 50/60 Hz operating frequency, with integrated bypass and adjustable current limitation."},{"question":"What is the mounting method and footprint?","answer":"Screw or snap-on DIN rail mounting. Dimensions: 45 mm wide, 125 mm tall, 155 mm deep. Requires 60 mm clearance above, 40 mm below, 15 mm to the side."},{"question":"Does the 3RW4028-1BB05 have an integrated bypass?","answer":"Yes, the integrated bypass contact system bridges the thyristors after start, so the soft starter doesn't dissipate heat during continuous running."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RW4028-1BB05","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/3RW4028-1BB05 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}}