{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RB3123-4QB0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RB3123-4QB0","canonicalUrl":"https://aoctrl.com/siemens/3RB3123-4QB0","factsUrl":"https://aoctrl.com/api/mcp/products/3RB3123-4QB0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RB3123-4QB0 solid-state overload relay, Size S0, 25 A thermal current, adjustable trip class 5E/10E/20E/30E, screw terminals, for contactor mounting.","salesMarkdown":"## Solid-state motor protection for S0 contactors The 3RB3123-4QB0: It mounts directly onto the contactor (fastening method: contactor mounting), so the assembly stays within the same DIN-rail footprint as the contactor itself — no extra panel space for a separate overload block. ## Trip class adjustability and motor current window Trip class is field-adjustable across CLASS 5E, 10E, 20E, and 30E — the same relay can be set for fast tripping on a pump (5E) or slower tripping on a high-inertia fan (30E) without swapping hardware. The motor current must fall between the lower current setting value and the upper setting value x 3.5 — this defines the usable motor FLA window the relay can protect. Screw terminals require a Pozidriv PZ2 tip with a 5 to 6 mm shaft diameter — standard electrician's screwdriver, no special tooling. ## Environmental tolerance and mounting flexibility Shock resistance is 15g / 11 ms (signaling contact in tripped position: 9g / 11 ms), and vibration resistance covers 1-6 Hz at 15 mm amplitude and 6-500 Hz at 20 m/s² over 10 cycles — this relay holds calibration on a conveyor line or a compressor skid. This is a solid-state overload relay, not a bimetallic thermal type — it uses current measurement and an electronic trip circuit, so it provides temperature-compensated protection and adjustable trip class without heating elements.","metaTitle":"Siemens 3RB3123-4QB0 SIRIUS solid-state overload relay, S0","metaDescription":"Siemens 3RB3123-4QB0 SIRIUS solid-state overload relay, 25 A thermal current, S0 frame, adjustable trip class 5E-30E. Active production, sourced to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Overload Relays"],"specifications":{"Note":"for message \"tripped\"","Depth":"84 mm","Solid":"1x (0.5 ... 4 mm²), 2x (0.5 ... 2.5 mm²)","Width":"45 mm","title":"3RB3123-4QB0","Height":"87 mm","Maximum":"IMotor < upper current setting value x 3.5","Minimum":"IMotor > lower current setting value","at 24 V":"2 A","at 60 V":"0.55 A","Per Pole":"0.4 W","Stranded":"2x 10 mm²","at 110 V":"0.3 A","at 120 V":"4 A","at 125 V":"0.3 A","at 220 V":"0.11 A","at 230 V":"3 A","Trip Class":"CLASS 5E, 10E, 20E and 30E adjustable","Rated Value":"690 V","description":"Overload relay 6...25 A Electronic For motor protection Size S0, Class 5...30 Contactor mounting Main circuit: Screw Auxiliary circuit: Screw Manual-Automatic-Reset Internal ground fault detection","During Storage":"-40 ... +80 °C","Thermal Current":"25 A","lifecycle_stage":"current","During Operation":"-25 ... +60 °C","During Transport":"-40 ... +80 °C","Fastening Method":"Contactor mounting","Shock Resistance":"15g / 11 ms","For Main Contacts":"M4","Mounting Position":"any","Solid Or Stranded":"1x (0,5 ... 4 mm²), 2x (0,5 ... 2,5 mm²)","Product Brand Name":"SIRIUS","Product Designation":"solid-state overload relay","Vibration Resistance":"1-6 Hz, 15 mm; 6-500 Hz, 20 m/s²; 10 cycles","at 480 V rated value":"25 A","at 600 V rated value":"25 A","Size Of Overload Relay":"S0","For Main Current Circuit":"screw-type terminals","Temperature Compensation":"-25 ... +60 °C","Design Of Screwdriver Shaft":"Diameter 5 to 6 mm","Size Of The Screwdriver Tip":"Pozidriv PZ 2","according to IEC 60068-2-27":"15g / 11 ms; Signaling contact 97 / 98 in position \"Tripped\": 9g / 11 ms","at AC-3e rated value maximum":"690 V","Substance Prohibitance (Date)":"10/01/2009","Design Of The Auxiliary Switch":"integrated","Design Of The Overload Release":"electronic","Operating Frequency Rated Value":"50 ... 60 Hz","Operational Current Rated Value":"25 A","for AC motors at 500 V at 50 Hz":"4 ... 15 kW","for AC motors at 690 V at 50 Hz":"5.5 ... 22 kW","for remote-reset function at DC":"24 V","For Auxiliary And Control Circuit":"screw-type terminals","Between Main And Auxiliary Circuit":"690 V","Relative Humidity During Operation":"10 ... 95 %","With Type Of Assignment 2 Required":"gG: 63 A, J: 100 A","Display Version For Switching Status":"Slide switch","Surge Voltage Resistance Rated Value":"6 kV","With Type Of Coordination 1 Required":"gG: 125 A, RK5: 100 A","at AWG cables for auxiliary contacts":"1x (20 ... 14), 2x (20 ... 14)","for 3-phase motors at 400 V at 50 Hz":"3 ... 11 kW","Of The Auxiliary And Control Contacts":"M3","Between Auxiliary And Auxiliary Circuit":"300 V","due to burst according to IEC 61000-4-4":"2 kV (power ports), 1 kV (signal ports) corresponds to degree of severity 3","reference code according to IEC 81346-2":"F","Finely Stranded With Core End Processing":"1x (0.5 ... 2.5 mm²), 2x (0.5 ... 1.5 mm²)","Number Of Poles For Main Current Circuit":"3","For Main Contacts With Screw-Type Terminals":"2 ... 2.5 N·m","number of CO contacts for auxiliary contacts":"0","number of NC contacts for auxiliary contacts":"1","number of NO contacts for auxiliary contacts":"1","For Auxiliary Contacts With Screw-Type Terminals":"0.8 ... 1.2 N·m","operational current at AC-3e at 400 V rated value":"25 A","Size Of Contactor Can Be Combined Company-Specific":"S0","electrostatic discharge according to IEC 61000-4-2":"6 kV contact discharge / 8 kV air discharge","Type Of Voltage Supply Via Input/Output Link Master":"No","contact rating of auxiliary contacts according to UL":"B600 / R300","Installation Altitude At Height Above Sea Level Maximum":"2 000 m","Response Time Of The Grounding Protection In Settled State":"1 000 ms","Response Value Current Of The Grounding Protection Minimum":"0.75 x IMotor","Arrangement Of Electrical Connectors For Main Current Circuit":"Top and bottom","For Short-Circuit Protection Of The Auxiliary Switch Required":"fuse gG: 6 A","insulation voltage with degree of pollution 3 at AC rated value":"690 V","Product Component Removable Terminal For Auxiliary And Control Circuit":"Yes","power loss [W] for rated value of the current at AC in hot operating state":"1.2 W","Adjustable Current Response Value Current Of The Current-Dependent Overload Release":"6 ... 25 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$101.60","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/e8f519a4d1e2d30b79746a9b0e95bced.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=464178&mlfb=3RB3123-4QB0"},"ai":{"faq":[{"question":"What is the 3RB3123-4QB0 used for?","answer":"It is a solid-state overload relay for motor protection, mounted directly onto an S0-frame contactor. It protects the motor against overload by monitoring current and tripping the contactor when current exceeds the set threshold for longer than the selected trip class allows."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RB3123-4QB0","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/3RB3123-4QB0 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}}