Skip to main content
Log in
Siemens 3RT1045-1AC20 — Contactors

Siemens 3RT1045-1AC20 SIRIUS Power Contactor, 45 kW at 500 V

MPN3RT1045-1AC20

Siemens SIRIUS 3RT1045-1AC20, size S3 power contactor, 45 kW at 500 V AC-3, screw-type terminals, 50/60 Hz coil 24 V, DIN rail mount.

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

3RT1045-1AC20 — Identification
ParameterValue
Contactor frame sizeS3
3RT1045-1AC20 — Ratings & Performance
ParameterValue
Rated operational current, AC-12, max.10 A
Rated operational current, AC-4 @ 400 V66 A
Rated value @ 400 V3 A
Rated value @ 500 V45 kW
Rated value @ 690 V21.1 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
3RT1045-1AC20 — Control & Coil
ParameterValue
Control supply voltage typeAC
Rated value @ 50 Hz0.8 ... 1.1
Rated value @ 50 Hz24 V
3RT1045-1AC20 — Contacts & Poles
ParameterValue
Main poles3
Main NO contacts3
Auxiliary contact reliability1 faulty switching per 100 million (17 V, 1 mA)
3RT1045-1AC20 — Protection & Coordination
ParameterValue
Short-circuit coordination type 1, fusefuse gL/gG: 250 A
Short-circuit coordination type 2, fusefuse gL/gG: 160 A
Aux. switch short-circuit protection, fusefuse gL/gG: 10 A
3RT1045-1AC20 — 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
3RT1045-1AC20 — Durability
ParameterValue
Durability (operating cycles, typ.)10 000 000
Durability with aux. switch block (cycles, typ.)10 000 000
3RT1045-1AC20 — Environmental
ParameterValue
Operating temperature range-25 ... +60 °C
Storage temperature range-55 ... +80 °C
Installation altitude, max.2 000 m
3RT1045-1AC20 — Mechanical
ParameterValue
Width70 mm
Height146 mm
Depth139 mm
3RT1045-1AC20 — Specifications
ParameterValue
At AC10 ... 25 ms

Product details

The Siemens 3RT1045-1AC20 is a SIRIUS size S3 power contactor, rated for switching motor loads up to 45 kW at 500 V in AC-3 duty, or 21.1 kW at 690 V. The 24 V 50/60 Hz coil draws the listed inrush and hold values. This is the current-production variant — no obsolescence flag on record.

The AC-1 rating (resistive load) would be higher, but for motor duty, AC-3 is the spec to match against your BOM. The AC-3 switching frequency is rated at 1 000 operating cycles per hour, which is typical for a size S3 contactor in conveyor or pump duty. The 24 V coil is rated for both 50 Hz and 60 Hz supply, with a tolerance band of 0.8 to 1.1 times rated voltage at 50 Hz and 0.85 to 1.1 at 60 Hz. The contactor carries IP20 on the front (finger-safe with cover/box terminal) and IP00 at the terminal itself — meaning the wiring area is not touch-safe without an additional enclosure. Side-by-side mounting is permitted, which saves panel width when grouping multiple contactors.

Frequently asked questions

What is the closest functional alternative if I cannot source this exact order code?

The 3RT1036-1AB00 is a smaller size S2 contactor from the same SIRIUS family. It will not drop into the same footprint without panel modification — the S3 frame is physically larger (146 mm height, 70 mm width, 139 mm depth vs the S2 dimensions). The AC-3 motor rating is lower on the S2, so verify your load current before substituting.

MPN
3RT1045-1AC20