{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RW4427-1BC35","brand":"Siemens","brandSlug":"siemens","productSlug":"3RW4427-1BC35","canonicalUrl":"https://aoctrl.com/siemens/3RW4427-1BC35","factsUrl":"https://aoctrl.com/api/mcp/products/3RW4427-1BC35","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RW4427-1BC35 soft starter, 161 A at 40 °C, 690 V insulation voltage, 50/60 Hz, integrated bypass, screw-type terminals.","salesMarkdown":"## Rated current and thermal derating — what the 161 A figure actually means for your motor The 3RW4427-1BC35: At 50 °C the rating drops to 142 A, and at 60 °C it falls to 125 A, so the panel ambient temperature directly governs the motor FLA you can connect. Derating begins at 40 °C; above that, the output must be reduced per the natural convection curve of the SIRIUS enclosure. ## Integrated bypass and inside-delta wiring — why this matters for heat and panel space An integrated bypass contact system is built in, so once the motor reaches full speed the thyristors are shorted and all heat generation stops — no external bypass contactor needed. Inside-delta circuit wiring is supported, which lets the soft starter handle a motor with the windings connected in delta while the starter sees phase current rather than line current — effectively doubling the current capability for the same unit. ## Mounting, clearances, and pollution degree — fitting it into the enclosure Mounting is by screw fixing; the unit can be rotated ±90° on a vertical surface or tilted ±22.5° front-to-back, giving flexibility in tight cabinets. Required clearances: 100 mm above, 75 mm below, and 5 mm at the sides — the vertical gap is critical for the thyristor heat sink convection path. Dimensions: 192 mm high, 170 mm wide, 270 mm deep — confirm the backpanel depth before laying out the gland plate. ## Protection, control, and minimum load — what the soft starter handles on its own Motor overload protection is built in, along with intrinsic device protection (thyristor overtemperature, phase imbalance, etc.) — no separate overload relay is required for most applications. Adjustable current limitation lets you set the starting current between the motor's no-load current and the unit's rated current, which is useful for limiting supply dips on weak grids. Minimum load is 8 % of the rated current — below that the soft starter may not detect the motor load correctly, so verify the motor no-load current exceeds this threshold. Maximum motor cable length is 500 m — beyond that, capacitive charging currents can cause nuisance tripping or thyristor misfiring. External reset input is available, and a display shows fault signals for on-device diagnostics.","metaTitle":"Siemens 3RW4427-1BC35 SIRIUS Soft Starter, 161 A at 40 °C","metaDescription":"Siemens 3RW4427-1BC35 SIRIUS soft starter, 161 A at 40 °C, 690 V insulation, integrated bypass, adjustable current limit. Active production, sourced per RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Soft Starters"],"specifications":{"Depth":"270mm","Solid":"2x (0.5 ... 2.5 mm²)","Width":"170mm","title":"3RW4427-1BC35","Height":"192mm","Upwards":"100mm","Stranded":"2x (4 ... 50 mm²)","Downwards":"75mm","Thyristors":"Yes","At The Side":"5mm","description":"SIRIUS soft starter Values at 575 V, 50 °C standard: 82 A, 75 hp Inside-delta: 142 A, 125 hp 400-600 V AC, 115 V AC Screw terminals!!! Phased-out product!!! Successor is SIRIUS 3RW5, Preferred successor type is >>3RW5527-1HA16<<","During Storage":"-25 ... +80°C","External Reset":"Yes","lifecycle_stage":"current","During Operation":"60°C","Fastening Method":"screw fixing","Minimum Load [%]":"8%","Mounting Position":"with vertical mounting surface +/-90° rotatable, with vertical mounting surface +/- 22.5° tiltable to the front and back","Product Brand Name":"SIRIUS","Degree Of Pollution":"3, acc. to IEC 60947-4-2","Product Designation":"Soft starter","Wire Length Maximum":"500m","Derating Temperature":"40°C","Inside-Delta Circuit":"Yes","at 50 Hz rated value":"115V","at 60 Hz rated value":"115V","at 40 °C rated value":"161A","at 50 °C rated value":"142A","at 60 °C rated value":"125A","For Auxiliary Contacts":"2x (20 ... 14)","For Main Current Circuit":"box terminal","Motor Overload Protection":"Yes","Using Both Clamping Points":"2x (10 ... 1/0)","Intrinsic Device Protection":"Yes","Adjustable Current Limitation":"Yes","Using The Back Clamping Point":"10 ... 2/0","Insulation Voltage Rated Value":"690V","Using The Front Clamping Point":"10 ... 2/0","Operating Frequency Rated Value":"50 ... 60Hz","Display Version For Fault Signal":"Display","Integrated Bypass Contact System":"Yes","For Auxiliary And Control Circuit":"screw-type terminals","Product Component Motor Brake Output":"Yes","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":"55kW","at standard circuit at 50 °C rated value":"75hp","Finely Stranded Without Core End Processing":"2x (4 ... 35 mm²)","number of CO contacts for auxiliary contacts":"1","number of NC contacts for auxiliary contacts":"0","number of NO contacts for auxiliary contacts":"3","Type Of Voltage Of The Control Supply Voltage":"AC","at inside-delta circuit at 40 °C rated value":"110kW","at inside-delta circuit at 50 °C rated value":"125hp","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","Operating Voltage At Inside-Delta Circuit Rated Value":"400 ... 600V","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 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":"55W","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":"18A","Relative Negative Tolerance Of The Operating Voltage At Inside-Delta Circuit":"-15%","Relative Positive Tolerance Of The Operating Voltage At Inside-Delta Circuit":"10%"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/85cfda0aff1d06c53736a6e756cf6ff9.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=334366&mlfb=3RW4427-1BC35"},"ai":{"faq":[{"question":"What is the maximum motor cable length for the 3RW4427-1BC35?","answer":"The maximum motor cable length is 500 m. Beyond this distance, capacitive charging currents in the cable can interfere with the thyristor firing and cause nuisance trips."},{"question":"Does the 3RW4427-1BC35 include an integrated bypass contactor?","answer":"Yes, an integrated bypass contact system is built in. Once the motor reaches full speed, the thyristors are bypassed and all heat generation stops — no external bypass contactor is needed."},{"question":"What is the minimum load current for the 3RW4427-1BC35?","answer":"The minimum load is 8 % of the rated current. For the 161 A version, that is about 12.9 A — verify the motor no-load current exceeds this threshold for reliable operation."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RW4427-1BC35","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/3RW4427-1BC35 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}}