{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RW4427-3BC35","brand":"Siemens","brandSlug":"siemens","productSlug":"3RW4427-3BC35","canonicalUrl":"https://aoctrl.com/siemens/3RW4427-3BC35","factsUrl":"https://aoctrl.com/api/mcp/products/3RW4427-3BC35","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RW4427-3BC35 soft starter, 161 A at 40 °C, 690 V insulation voltage, integrated bypass, screw fixing, 170 x 192 x 270 mm.","salesMarkdown":"## Rated current and thermal derating — the real-world numbers The 3RW4427-3BC35 is rated 161 A at 40 °C ambient — that's the headline figure for a standard panel environment. At 50 °C the continuous rating drops to 142 A, and at 60 °C it's 125 A. The derating temperature threshold is 40 °C, so any enclosure that runs hotter needs the next frame up or forced ventilation. Minimum load is 8 % of the rated current — important for lightly loaded motors or pumps that start near no-load. Below that threshold the soft starter may not trigger the bypass reliably. ## Integrated bypass and inside-delta wiring An integrated bypass contact system is built in — once the motor reaches full speed, the thyristors are shorted out, eliminating heat dissipation in the power section during run. This means the enclosure thermal budget is based on start duty only, not continuous conduction. Inside-delta circuit connection is supported, which lets the soft starter handle higher motor currents by wiring the power section inside the delta loop of a six-lead motor. This is a common retrofit trick to keep the same starter when upsizing a motor without rewiring the panel. Motor overload protection is included, and the device also provides intrinsic device protection — the thyristor junction temperature is monitored, not just the motor current. Adjustable current limitation gives you a hard cap on starting current, useful for weak supply lines or generator-fed sites. ## Mounting and wiring — panel fit and clearances Fastening is screw fixing, not DIN rail snap-on. The dimensions are 170 mm wide, 192 mm high, 270 mm deep — that's a substantial footprint, so check the backplate layout before committing. Mounting position allows vertical surface with +/-90° rotation and +/-22.5° tilt front-to-back, giving flexibility in tight enclosures. Clearance requirements: 100 mm above, 75 mm below, 5 mm at the sides. The 75 mm below is the critical one — it's needed for the main power cable bend radius and for accessing the box terminals. Main current circuit uses box terminals, accepting stranded cable 2x (4... 50 mm²) or using both clamping points 2x (10... 1/0 AWG). The auxiliary and control circuit uses spring-loaded terminals for 2x (24... 16 AWG) solid or stranded. Maximum wire length from the starter to the motor is 500 m — beyond that, voltage drop and cable capacitance can cause nuisance trips. The SIRIUS brand is Siemens' industrial controls family, and this soft starter sits in the 3RW44 series — the high-feature line with integrated bypass, inside-delta capability, and adjustable current limit. For a panel-builder or MRO buyer, this is the part to specify when the motor is over 100 A and the panel has the vertical clearance.","metaTitle":"Siemens 3RW4427-3BC35 SIRIUS Soft Starter, 161A, 690V","metaDescription":"Siemens 3RW4427-3BC35 SIRIUS soft starter, 161A at 40°C, 690V insulation voltage, integrated bypass. Active production, sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Soft Starters"],"specifications":{"Depth":"270mm","Solid":"2x (0.25 ... 1.5 mm²)","Width":"170mm","title":"3RW4427-3BC35","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 spring-type terminals!!! Phased-out product!!! Successor is SIRIUS 3RW5, Preferred successor type is >>3RW5527-3HA16<<","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 (24 ... 16)","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":"spring-loaded 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 (0.25 ... 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":"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%","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":"$4,465.32","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/bd3f7060ac9325725ca7abd7bbb4c47a.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=265837&mlfb=3RW4427-3BC35"},"ai":{"faq":[{"question":"What is the 3RW4427-3BC35 rated current at different temperatures?","answer":"The derating temperature threshold is 40 °C."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RW4427-3BC35","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/3RW4427-3BC35 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}}