Siemens SIRIUS 3RF23 and 3RB3 Overload Relays in 2026: Reading Motor Control Stocking Around the Circular Soft-Starter Launch, DC Protection Portfolio Expansion, and SIMOCODE 3UF7 Motor Management

Siemens SIRIUS 3RF23 and 3RB3 Overload Relays in 2026: Reading Motor Control Stocking Around the Circular Soft-Starter Launch, DC Protection Portfolio Expansion, and SIMOCODE 3UF7 Motor Management

Your motor starter cabinet is full of small blocks you barely think about. The 3RF23 solid-state relay on the heating circuit, the 3RB31 electronic overload on the conveyor, the SIMOCODE 3UF7 basic unit on the PROFIBUS line — none of them are headline parts. Then Siemens announced a circular soft starter in March 2026 and a DC protection portfolio in April 2026. Now those line items have a context shift to plan around.

This piece is for the engineer or buyer who suddenly has to decide whether to keep ordering 3RF2310-1AA04 the same way, or to start asking whether the surrounding 3RB3, 3RT, and 3UF7 family will follow the same circularity logic. The article walks through the 2026 Siemens announcements, what they actually change for a panel shop, and what our catalog currently carries across the SIRIUS motor-control range.

The market situation (as of August 2026)

Two announcements from Siemens in 2026 are reshaping how the SIRIUS family is positioned.

Siemens debuted a circular soft starter and an expanded semiconductor-based circuit protection portfolio in early March 2026. Siemens press release dated March 5, 2026 framed the launch as the first soft starter designed for a circular economy — refurbished drives and switchgear intended to be returned, remanufactured, and re-deployed rather than scrapped. Engineering.com, IT Brief Asia, and Indian Chemical News all carried the announcement on March 6, 2026 with the same framing: a refurbished starter built around the same SIRIUS 3RW form factor, but with a documented remanufacturing path. For panel shops and OEM skid builders, the relevant question is not whether the design is greener, but whether the circular soft starter pulls legacy 3RW40 / 3RW44 parts into an end-of-life window.

Siemens added a DC protection and switching portfolio in mid-April 2026. Siemens press release dated April 15, 2026 — and covered by Drives & Controls, Engineering.com (April 21, 2026), and Indian Chemical News (April 16, 2026) — framed this as a response to growing direct-current distribution on industrial sites. The portfolio covers solid-state DC breakers, semiconductor-based switching modules, and updated SIRIUS components engineered for DC up to 1500 V. For buyers already specifying 3RF23 solid-state relays for AC heating circuits, the announcement is a signal that the same semiconductor-switching line will see a DC-side variant — not a 1:1 replacement, but an expansion of what the platform covers.

Two market-research reports in August 2026 put the soft-starter market in a clear growth path. Future Market Insights published a Soft Starter Systems Market report on August 21, 2026 forecasting sustained growth through the mid-2030s, with industrial automation and HVAC as the leading application segments. SNS Insider published a Soft Starter Industry Trends & Leading Key Players report on August 10, 2026 listing Siemens, ABB, Schneider Electric, Eaton, and Rockwell Automation as the named suppliers. Both reports converge on the same conclusion: semiconductor-based starting and protection is moving from a premium option to a baseline expectation.

What this signals for panel builders

Three things, layered:

• Spec pressure: the soft-starter category is no longer a special order. As of August 2026, every major OEM datasheet in the SIRIUS / Altivar / PSE family includes a semiconductor variant. Buyers who still default to a direct-on-line contactor + thermal overload for new builds are missing a category that has shifted under them.
• Stock pressure: the circular soft starter launch is a soft signal that certain 3RW part numbers may move into a refurbished-only supply chain. That does not mean stock-out. It does mean the timing of orders matters more than it did two years ago.
• Substitution pressure: the DC protection portfolio expansion signals that semiconductor switching on the AC side (3RF23) and the DC side are converging on similar thermal-management designs. A panel shop specifying both AC heating control and DC bus switching can now order from a single supplier family, which simplifies approvals but also reduces your substitution options.

What this means for SIRIUS buyers

If your cabinet is built on SIRIUS — and most EU, UK, and Southeast Asia panels are — the 2026 announcements turn a routine re-order into a small decision tree.

• Heating and resistive loads: the 3RF23 family is unchanged in catalog position. The solid-state contactor remains a high-cycle, silent-switching alternative to a mechanical contactor on resistive heating, hot runner, or furnace control. What has shifted is the adjacent offering: the DC protection portfolio means a panel that mixes resistive heating and DC switching can be specified on a unified platform, which matters for CE / UL documentation cycles.
• Motor starting: the 3RW circular soft starter announcement is a positioning move, not a 3RW40 / 3RW44 EOL. Existing builds can keep ordering the same SKU. New builds where the panel-shop buyer has discretion should at least evaluate the circular path, especially on three-phase motor protection assemblies where the motor rating is between 5.5 kW and 250 kW — the range the circular soft starter targets.
• Overload protection: the 3RB31 electronic overload relay is the workhorse. It is not directly affected by either announcement. What is affected is the firmware and configuration expectation: as more panel builders adopt SIMOCODE 3UF7 with PROFINET / OPC UA, the 3RB31 becomes the local-fallback for cabinets that don't need full motor management. A reasonable panel-shop policy in late 2026 is to keep 3RB31 as the default for IP20 cabinets under 100 A, and move to SIMOCODE 3UF7 when there is a bus requirement.
• Motor management: SIMOCODE pro C (3UF7000) and SIMOCODE pro V (3UF7011) are the parts that benefit from the DC portfolio launch. PROFINET, OPC UA, and PROFINET system redundancy are now table stakes. The 3UF7210 operator panel and the 3UF7320 fail-safe digital module DM-F remain the add-ons that turn a basic SIMOCODE unit into a safety-integrated motor manager.

Where to be careful

Three pitfalls the announcements do not address but you will hit:

• DC protection is not a free upgrade to AC. A 3RF2310-1AA04 is rated for AC-51 use at 48-460 V, 10 A. The DC protection portfolio is a different SKU family. Do not assume a 3RF23 can be re-rated for DC just because Siemens released a DC portfolio.
• Circular does not mean stock-on-hand. A circular soft starter is a refurbished part. Lead time on the refurbished path is longer than a new 3RW in many regions because the take-back loop takes weeks.
• SIMOCODE 3UF7 needs the expansion modules sized in your BOM. A 3UF7011 basic unit alone gives you 4 inputs / 3 outputs. The DM-F fail-safe module (3UF7320) adds the safety I/O. Specify the whole stack — not just the basic unit — if the panel is meant to be SIL 2 / SIL 3.

What's in our catalog

Our Siemens SIRIUS stock spans the motor-control line. Here is what the catalog carries at aiDemandScore 95, and what each part does in real panel builds.

3RF23 — Solid-state relays and contactors

3RF2310-1AA04 — solid-state contactor, 1-phase, AC-51 / 10 A at 40 °C, 48-460 V load, 24 V DC control, screw terminal. Rated supply voltage 48-460 V at 50/60 Hz, ON-delay 1 ms plus half-wave. Width 22.5 mm, depth 88 mm, height 95 mm. This is the standard part for switching resistive heating elements — furnace banks, hot runner manifolds, plastic-extrusion heaters — where mechanical contactors wear out at switching frequencies above the 1 million-cycle range. aiDemandScore 95 reflects its presence in roughly every hot-runner panel coming out of the Pearl River Delta. Specs verified across two raw canonical data sources; commercial offer range is currently $0 to $179.14 across tracked channels.

3RB3 — Electronic overload relays

3RB3113-4PB0 — electronic overload relay, 1 to 4 A current setting, Size S00, trip class 5 / 10 / 20 / 30 adjustable, contactor mounting, screw main circuit, internal ground-fault detection. Rated insulation voltage 690 V with pollution degree 3, surge voltage resistance 6 kV, thermal current 4 A. Operating ambient -25 to +60 °C, storage -40 to +80 °C, vibration resistance 1-6 Hz at 15 mm / 6-500 Hz at 20 m/s², shock 15g / 11 ms. Power loss at AC hot state 0.1 W; AC-3e at 400 V rated operational current 4 A. For 3-phase motors at 400 V / 50 Hz: covers 0.37 to 1.5 kW. For AC motors at 500 V / 50 Hz: 0.37 to 2.2 kW. For AC motors at 690 V / 50 Hz: 0.55 to 3 kW. Auxiliary contacts: 1 NO + 1 NC. The grounding-fault response threshold is 0.75 × IMotor with a 1000 ms settled-state response. aiDemandScore 95 reflects its position as the most-requested S00-frame electronic overload for new conveyor and small-pump panels. Commercial offer range $0 to $343.12 across tracked channels.

3RT — Power contactors

3RT2026-1BM40 — power contactor, AC-3e / AC-3 25 A, 11 kW at 400 V, 3-pole, 220 V DC coil with integrated varistor, 1 NO + 1 NC auxiliary, screw terminal, Size S0. AC-3e rated operational voltage up to 690 V, AC-4 at 400 V up to 15.5 A, AC-2 at 400 V 11 kW. Surge voltage 6 kV main circuit, holding power 5.9 W DC, no-load loss typical 5.9 W. aiDemandScore 95; offer range $0 to $290.55.

3RT2035-1KB40 — power contactor, AC-3e / AC-3 41 A, 18.5 kW at 400 V, 3-pole, 24 V DC coil with integrated varistor, 1 NO + 1 NC auxiliary, screw terminal, Size S2. AC-3e up to 690 V, AC-2 at 400 V 18.5 kW, AC-4 at 400 V 35 A, 460/480 V 30 hp, 575/600 V 40 hp. Surge voltage 6 kV main circuit, holding power 1 W DC, no-load loss typical 1 W. aiDemandScore 95; offer range $0 to $271.23.

3RT2036-1AK60, 3RT2037-1KB40 — additional S2-frame contactors at 50 A and 65 A respectively, both at aiDemandScore 95. Sized for 22 kW and 30 kW @ 400 V three-phase motors.

3RA2 — Fuseless motor starter assemblies

3RA2115-0EA15-1AK6 — fuseless motor starter, direct-on-line, 600 V AC, Size S00, 0.28-0.4 A current setting, 110/120 V AC 50/60 Hz coil, screw connection. Width 45 mm, height 167.2 mm, depth 97.1 mm, trip class 10. aiDemandScore 95.

3RA2120-1GA24-0AP6 — fuseless motor starter, direct-on-line, Size S0, with wiring accommodations for rail mounting. aiDemandScore 95.

3RA2220-4DB27-0AP6 — fuseless motor starter, reversing operation, 600 V AC, Size S0, 20-25 A current setting, 220/240 V AC 50/60 Hz coil, screw connection. Width 90 mm, height 265 mm, depth 120 mm, trip class 10. aiDemandScore 95. This is the part to specify when the panel needs mechanical reversing via contactor interlocking rather than VFD control.

3UF7 — SIMOCODE motor management

3UF7000-1AU00-0 — basic unit, SIMOCODE pro C, PROFIBUS DP interface 12 Mbit/s, RS-485, 4 freely parameterizable inputs / 3 outputs, control supply 110-240 V AC/DC, thermistor input, current measuring module, blocking current evaluation, monitoring of number of start operations. IP20, 2.9 W active power consumption, 5.3 VA apparent. aiDemandScore 95; offer range $0 to $494.00 across tracked channels.

3UF7011-1AB00-1-ZI41 — basic unit, SIMOCODE pro V PN GP, Ethernet / PROFINET IO with PROFINET system redundancy, OPC UA server, web server, 100 Mbps transfer rate, 2 × RJ45 bus connection, 4 inputs / 3 outputs freely parameterizable, 24 V DC supply, monostable relay outputs, thermistor connection, expandable by 1 module (DM / TM / EM), firmware V3.0.0. aiDemandScore 95. This is the part to specify when the cabinet has a PROFINET backbone and the customer wants OPC UA telemetry.

3UF7210-1BA01-0 — operator panel with display for SIMOCODE pro V, for installation in cabinet door or front plate, plugs onto basic unit or expansion module. IP54 on the front, 0.3 W consumption, vertical mounting. aiDemandScore 95.

3UF7320-1AB00-0 — fail-safe digital module DM-F local, for fail-safe shutdown via hardware signal, 24 V DC supply, 2 relay enabling circuits, 2 relay outputs, safe isolation, monitoring of magnetically operated switches (NC-NC and NC-NO), 5 inputs, IP20. Buffers 60 ms on power loss, typical 8000 ms / maximum 8200 ms after power failure. aiDemandScore 95. Pair with 3UF7011 to bring the motor controller up to SIL 2 / SIL 3.

3RH21 — Auxiliary contactors

3RH2140-1AP00 — 4-pole auxiliary contactor for control circuit interlocking and signaling, aiDemandScore 95. Pairs with 3RT contactors in safety circuits.

3UF7 motor monitoring vs. 3RB31 electronic overload — when to use which

A practical panel-shop rule of thumb as of August 2026:

The 3RB31 is the right call for IP20 cabinets under 100 A and under 50 kW. Above that, or any time the cabinet has a bus requirement, SIMOCODE 3UF7 pays for itself in commissioning time.

Buying advice: RFQ / lead time / substitutes / authenticity

When to RFQ now vs. wait

For the parts in this article, RFQ now is the right move in three cases:

1. 3RB3113-4PB0 and the 3RT2035-1KB40 / 3RT2037-1KB40 pair: these are the volume movers in any panel shop shipping conveyors or HVAC pump skids in the second half of 2026. Lead times across the S0 and S2 frames have been quoted at 6 to 12 weeks through most franchised channels as of August 2026. Hold a 30-day rolling buffer on these SKUs if your build rate is stable.

2. 3UF7011-1AB00-1-ZI41 (SIMOCODE pro V PN GP): PROFINET-system-redundancy stock is thinner than the basic PROFIBUS SIMOCODE pro C. If your cabinet design has just locked onto PROFINET redundancy, lock the supply too. Lead times on PROFINET V basic units are commonly 8 to 16 weeks depending on the firmware version.

3. 3RA2220-4DB27-0AP6 reversing assemblies: the S0-frame reversing starter is a slow-mover at the distributor level and many channels keep only single-digit stock. A 4-week ordering buffer is reasonable.

When to wait

• 3RF2310-1AA04 is widely held across distributors; routine orders can run on standard procurement cadence.
• 3UF7000-1AU00-0 (SIMOCODE pro C, PROFIBUS) is a legacy part but still in active production; standard 4-6 week lead time applies.

MOQ and packaging

For these part numbers, MOQ is one piece. Distributors will sell singles for build use; you do not need to commit to case-pack quantities. If your panel shop is buying more than 50 pieces of any single SKU per quarter, ask the distributor for a serialized stock release — many independent industrial automation distributors will reserve partial-lot stock against a blanket PO.

Substitutes that work (and ones that don't)

Schneider Altivar ATS480 substitutes for 3RW-series soft starters on three-phase motors up to 900 A, but the form factor is different and the cabinet layout has to be redesigned. Don't substitute at the panel-shop RFQ stage without a layout review.

ABB PSE soft starters substitute for 3RW on 5.5 to 250 kW three-phase motors. Same caveat on form factor.

Chint NXC and NXR contactors substitute for 3RT2026 / 3RT2035 on the mechanical side, but the coil voltages and the auxiliary contact layout are not 1:1. The catalog carries Chint NC1 contactors for cost-optimized builds; those suit greenfield builds where the customer accepts the certification delta, not on UL 508A panels with a Siemens specification carry-over.

For solid-state relays, Crydom and Carlo Gavazzi RGC / RGS series are the closest substitutes for 3RF23 — but again, verify the thermal-management envelope; a 10 A AC-51 solid-state relay has very different heat-sink requirements across brands.

Authenticity checks on Siemens SIRIUS

Siemens labels on SIRIUS 3RF23 / 3RB3 / 3RT / 3UF7 should pass three checks before installation:

1. Laser-etched label, not printed. A genuine SIRIUS label is laser-etched into the housing face, not printed on adhesive paper. A printed label that rubs off with isopropyl alcohol is a counterfeit signal.
2. Data matrix code on the side face. Every current-production SIRIUS carries a data matrix code on the side face that resolves in the Siemens Industry Online Support portal to a verified article number. Scan with any smartphone Industry Support app — if the code does not resolve, do not install.
3. SIRIUS molded mark on the housing. A genuine SIRIUS 3RF23, 3RB3, or 3UF7 has the SIRIUS brand mark molded into the housing at the factory. A missing brand mark is a major counterfeit signal.

If a quote comes in significantly below distributor cost on a 3RB3113-4PB0 or 3UF7011-1AB00-1-ZI41, treat it as a flag, not a discount. Counterfeit Siemens SIRIUS motor protection has been documented in the open market, especially on the legacy 3RB30 thermal overload family.

A note on the circular soft starter announcement

The Siemens circular soft starter is a real product, but it is not a direct replacement for the 3RW40 / 3RW44 stock you have on hand. The circular path is a refurbished-supply option intended for customers with a documented take-back process and a longer planning horizon. For panel shops shipping 10-50 panels a month with standard 3RW ordering, the right call for the rest of 2026 is:

• Continue to order 3RW40 and 3RW44 from your current channel.
• Lock a 6-week buffer on the 3RW ratings your shop uses most.
• If a customer explicitly asks for circular, ask Siemens or your distributor for the take-back loop and the typical refurbishment lead time in your region before committing to a delivery date.

The DC protection portfolio expansion is more directly relevant. If your 2026-2027 builds are starting to include DC bus switching on solar-coupled or battery-backed industrial systems, the new Siemens DC product family is worth evaluating — not as a replacement for AC-side SIRIUS, but as an addition to the BOM.

The takeaway

The SIRIUS family is not in EOL. It is being reorganized around a circular-economy positioning on the soft-starter side and a DC-switching expansion on the protection side. Panel shops that keep their 3RF23 / 3RB3 / 3UF7 stocking rhythm and add a small DC-evaluation branch to the 2027 specification tree are positioned well. Panel shops that read the circular soft starter as a signal to stop ordering 3RW should re-check the press release; the take-back loop is a supply option, not an exit notice. Order what the cabinet needs, verify each Siemens label on arrival, and keep the BOM lean across 3RF23, 3RB3, and SIMOCODE 3UF7 — that is the path through the rest of 2026 and into 2027.