{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RH1140-1WB40","brand":"Siemens","brandSlug":"siemens","productSlug":"3RH1140-1WB40","canonicalUrl":"https://aoctrl.com/siemens/3RH1140-1WB40","factsUrl":"https://aoctrl.com/api/mcp/products/3RH1140-1WB40","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS auxiliary contactor, 3RH1140-1WB40, 24 VDC coil, 4 NO instantaneous contacts, S00 frame, IP20 front, with varistor surge suppression.","salesMarkdown":"It's part of the SIRIUS family, built on the S00 frame size, which is the compact footprint for smaller control loads. It carries 4 normally-open (NO) instantaneous contacts — no delayed, lagging, or make-before-break options on this variant. That means all four close the instant the coil picks up, and all four open the instant it drops out. Useful when you need multiple independent control signals to switch simultaneously. The coil is rated 24 VDC, with a pick-up threshold of 85% of rated voltage (so 20.4 VDC minimum to pull in) and a dropout around 15% (roughly 3.6 VDC). Holding power is a steady 1.4 W DC — no AC hum, no inrush spike to manage. The contact ratings are given per voltage for AC-12 duty (resistive loads at rated voltage): 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. For inductive or motor loads, derate accordingly — this is an auxiliary contactor, not a power contactor. The 10 A maximum at AC-12 tells you it's sized for control circuits, not main motor switching. Electrical life will be shorter depending on switched current and load type, but the mechanical figure gives you a sense of the design margin for high-cycle applications like conveyor interlocks or valve position feedback. Surge suppression is built in — a varistor across the coil. That saves you from adding an external snubber or diode on the DC coil, which is one less thing to wire and one less failure point. The varistor clips voltage spikes when the coil de-energizes, protecting nearby PLC outputs or relay contacts. ## Mounting and environment — what fits in the van The S00 frame is 45 mm wide, 57.5 mm tall, and 72 mm deep, so it tucks into tight enclosures alongside the main contactor. That covers most panel layouts without worrying about orientation derating. IP20 on the front — finger-safe but not sealed. No washdown rating here; it belongs in a closed cabinet, not on a food line or outdoors. Shock resistance is 10g for 5 ms and 5g for 10 ms — fine for most industrial panels on machine frames, but not rated for continuous vibration from a large unbalanced motor or crusher. If the panel is on a vibrating platform, you'll want to check the mounting position and add vibration dampers. Terminals accept solid or stranded wire: 2x 0.5 to 1.5 mm², 2x 0.75 to 2.5 mm², or 2x 4 mm². That covers common control wiring sizes — 1.5 mm² for most signal runs, 2.5 mm² for longer distances or daisy-chained commons. The dual-entry per terminal lets you loop through without a separate terminal block. Clearance on the sides is 0 mm — meaning you can butt it against adjacent devices on the DIN rail without derating. That's a space-saver in dense panels. Above that, air density drops and clearance/creepage distances may need to be increased. For most plant-floor installations below 2,000 m, this is a non-issue.","metaTitle":"Siemens SIRIUS 3RH1140-1WB40 Auxiliary Contactor, 24 VDC, 4","metaDescription":"Siemens SIRIUS 3RH1140-1WB40 auxiliary contactor, 24 VDC coil, 4 NO contacts, S00 frame, IP20 front, varistor suppression. Active production.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Contactors"],"specifications":{"Depth":"72 mm","Solid":"2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²), 2x 4 mm²","Width":"45 mm","Height":"57.5 mm","Maximum":"2 000 m","At The Side":"0 mm","Rated Value":"24 V","On The Front":"IP20","Initial Value":"0.85","Mounting type":"screw and snap-on mounting","During Storage":"-55 ... +80 °C","Leading Contact":"0","lifecycle_stage":"current","Auxiliary switch":"No","During Operation":"-25 ... +60 °C","During Transport":"-55 ... +80 °C","Full-scale value":"1.85","Shock resistance":"10g / 5 ms and 5g / 10 ms","Delayed Switching":"0","Lagging Switching":"0","Mounting position":"+/-180° rotation possible on vertical mounting surface; can be tilted forward and backward by +/- 22.5° on vertical mounting surface","Size of contactor":"S00","Product brand name":"SIRIUS","Degree of pollution":"3","Product designation":"Auxiliary contactor","at 24 V rated value":"10 A","Of Contactor Typical":"30 000 000","at 110 V rated value":"1 A","at 220 V rated value":"0.27 A","at 230 V rated value":"6 A","at 400 V rated value":"3 A","at 500 V rated value":"2 A","at 690 V rated value":"1 A","Instantaneous Contact":"4","For Auxiliary Contacts":"0","Make-Before-Break Switching":"0","Design of the surge suppressor":"with varistor","Closing power of magnet coil at DC":"1.4 W","Holding power of magnet coil at DC":"1.4 W","Operating current at AC-12 maximum":"10 A","Surge voltage resistance rated value":"6 kV","Reference code acc. to DIN EN 61346-2":"K","Reference code acc. to DIN EN 81346-2":"K","with low demand rate acc. to SN 31920":"40 %","with high demand rate acc. to SN 31920":"75 %","Finely Stranded With Core End Processing":"2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²)","at AWG conductors for auxiliary contacts":"2x (20 ... 16), 2x (18 ... 14), 1x 12","Contact reliability of auxiliary contacts":"1 faulty switching per 100 million (17 V, 1 mA)","For Auxiliary And Control Current Circuit":"screw-type terminals","Of Auxiliary Contacts Instantaneous Contact":"0","Number of NC contacts for auxiliary contacts":"0","Number of NO contacts for auxiliary contacts":"4","with degree of pollution 3 at AC rated value":"690 V","Type of voltage of the control supply voltage":"DC","Identification number and letter for switching elements":"40 E","For Short-Circuit Protection Of The Auxiliary Switch Required":"fuse gL/gG: 10 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$144.36","priceTiers":null},"links":{"datasheetUrl":null,"sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=235565&mlfb=3RH1140-1WB40","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RH1140-1WB40/alternatives.json"},"ai":{"faq":[{"question":"What are the key contact ratings for this auxiliary contactor?","answer":"AC-12 resistive ratings: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, 1 A at 690 V. The 10 A maximum at AC-12 defines its control-circuit capability."},{"question":"Does the 3RH1140-1WB40 include surge suppression?","answer":"Yes, a varistor is built across the coil. No external snubber or flyback diode is needed for the 24 VDC coil."},{"question":"What frame size and mounting options does this contactor have?","answer":"It's the S00 frame — 45 mm wide, 57.5 mm tall, 72 mm deep. Mounts via screw or snap-on to DIN rail. Side clearance is 0 mm for tight panel layouts."},{"question":"What wire sizes does the terminal block accept?","answer":"Solid or stranded wire: 2x 0.5 to 1.5 mm², 2x 0.75 to 2.5 mm², or 2x 4 mm² per terminal. Dual-entry allows looping through."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RH1140-1WB40","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/3RH1140-1WB40 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-09-02T08:15:54.622Z","lastPublished":"2026-09-02T08:15:54.622Z","indexable":true}}