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Siemens 3RT1044-1BW40 — Contactors

Siemens 3RT1044-1BW40 SIRIUS Power Contactor, Size S3, 37 kW

MPN3RT1044-1BW40

Siemens SIRIUS power contactor, size S3, 3RT1044-1BW40, 37 kW at 500 V AC-3, screw-type terminals, snap-on mounting.

Source DocumentedChannel stated on listing & quote
Condition PhotosReal unit photos / video on request
WhatsApp AnswersFast human replies for machine-down parts
Worldwide DispatchDHL/FedEx — transit quoted per order
Independent China distributor & sourcing agent· Listing updated Sep 2026

Specifications

3RT1044-1BW40 — Identification
ParameterValue
Contactor frame sizeS3
3RT1044-1BW40 — Ratings & Performance
ParameterValue
Rated operational current, AC-12, max.10 A
Rated operational current, AC-4 @ 400 V55 A
Rated value @ 400 V3 A
Rated value @ 500 V37 kW
Rated value @ 690 V18.6 kW
Rated value @ 230 V6 A
Rated value @ 24 V10 A
Rated value @ 60 V2 A
Rated value @ 110 V1 A
Rated value @ 220 V0.3 A
3RT1044-1BW40 — Control & Coil
ParameterValue
Control supply voltage typeDC
3RT1044-1BW40 — Contacts & Poles
ParameterValue
Main poles3
Main NO contacts3
Auxiliary contact reliability1 faulty switching per 100 million (17 V, 1 mA)
3RT1044-1BW40 — Protection & Coordination
ParameterValue
Short-circuit coordination type 1, fusefuse gL/gG: 250 A
Short-circuit coordination type 2, fusefuse gL/gG: 125 A
Aux. switch short-circuit protection, fusefuse gL/gG: 10 A
3RT1044-1BW40 — Connection & Mounting
ParameterValue
Main circuit connectionscrew-type terminals
Aux. / control circuit connectionscrew-type terminals
Conductor cross-section, solid2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²), max. 2x (0.75 ... 4 mm²)
Conductor cross-section, solid or stranded2x (2.5 ... 16 mm²)
Conductor cross-section, finely stranded w/ ferrule2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²)
Mounting methodscrew and snap-on mounting onto 35 mm and 75 mm standard mounting rail
Side-by-side mountingYes
3RT1044-1BW40 — Durability
ParameterValue
Durability (operating cycles, typ.)10 000 000
Durability with aux. switch block (cycles, typ.)10 000 000
3RT1044-1BW40 — Environmental
ParameterValue
Operating temperature range-25 ... +60 °C
Storage temperature range-55 ... +80 °C
Installation altitude, max.2 000 m
3RT1044-1BW40 — Mechanical
ParameterValue
Width70 mm
Height146 mm
Depth152 mm

Product details

Rated for 37 kW at 500 V in AC-3 duty (motor starting/switching) and 55 A at 400 V in AC-4 duty (reversing/inching), the contactor handles the mechanical endurance of 10 million typical cycles. The AC-3 switching rate reaches 1000 operations per hour; AC-4 is derated to 300 operations per hour. Main circuit connections use screw-type terminals. Solid wire acceptance ranges from 2x 0.5...1.5 mm² up to 2x 0.75...4 mm²; stranded wire accepts 2x 10...50 mm². The auxiliary/control circuit accepts 2x 2.5...16 mm² solid or stranded. The enclosure carries IP20 on the front with the cover or box terminal fitted; the terminal itself is rated IP00.

Dimensions are 146 mm high, 70 mm wide, 152 mm deep. The 70 mm width is a standard S3 footprint, allowing direct replacement in panels where a size S3 contactor was originally specified. Snap-on mounting onto 35 mm or 75 mm DIN rail speeds installation; screw mounting is also supported for vibration-prone environments. Side-by-side mounting is explicitly permitted, so multiple contactors can be ganged without additional spacing — useful for grouped motor starter assemblies where panel width is constrained.

The contactor carries no known material compliance gaps for EU or global industrial markets.

Ratings in Context

The 37 kW rating at 500 V AC-3 is the headline motor-switching capacity. At 690 V, the motor power rating is 18.6 kW, reflecting the reduced current capability at higher voltage. For resistive loads (AC-1), the switching rate is 1000 operations per hour; for AC-4 reversing duty, the rate drops to 300 operations per hour due to increased contact wear. The DC switching ratings are modest: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V. Arcing time in DC circuits is 14...20 ms, compared to 10...15 ms for AC. This contactor is primarily intended for AC motor loads; DC applications should be verified against the load break current. The wider storage range reflects handling and transport conditions, not running operation.

Frequently asked questions

What is the closest alternative to 3RT1044-1BW40?

The 3RT1044-1FB46 is a functional peer within the same SIRIUS size S3 family. The key difference is the coil voltage: the 1BW40 uses a 48 V DC coil (rated value 48 V), while the 1FB46 uses a different coil voltage. Verify coil compatibility before substituting.

Will 3RT1044-1BW40 drop into a panel specified for 3RT1044-1FB46?

Mechanically yes — both are size S3 with the same 70 mm width, 146 mm height, 152 mm depth, and snap-on DIN rail mounting. The wiring terminals are identical. The only difference is coil voltage, so verify the control circuit voltage before substitution.

MPN
3RT1044-1BW40