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Siemens 3RT1025-3KF40 — Contactors

Siemens 3RT1025-3KF40 SIRIUS Power Contactor, 110 VDC Coil,

MPN3RT1025-3KF40

Siemens SIRIUS power contactor, size S0, 3RT1025-3KF40, 110 VDC coil with varistor, screw and snap-on 35 mm DIN rail mount, IP20 front / IP00 terminals.

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

3RT1025-3KF40 — Identification
ParameterValue
Contactor frame sizeS0
3RT1025-3KF40 — Ratings & Performance
ParameterValue
Rated operational current, AC-4 @ 400 V15.5 A
Rated value @ 400 V3 A
Rated value @ 500 V10 kW
Rated value @ 690 V11 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
3RT1025-3KF40 — Control & Coil
ParameterValue
Control supply voltage typeDC
3RT1025-3KF40 — Contacts & Poles
ParameterValue
Main poles3
Main NO contacts3
Auxiliary contact reliability1 faulty switching per 100 million (17 V, 1 mA)
3RT1025-3KF40 — Protection & Coordination
ParameterValue
Short-circuit coordination type 1, fusefuse gL/gG: 63 A
Short-circuit coordination type 2, fusefuse gL/gG: 25 A
Aux. switch short-circuit protection, fusefuse gL/gG: 10 A
3RT1025-3KF40 — Connection & Mounting
ParameterValue
Conductor cross-section, solid2x (0.25 ... 2.5 mm²)
Conductor cross-section, finely stranded w/ ferrule2x (0.25 ... 1.5 mm²)
Side-by-side mountingYes
3RT1025-3KF40 — Durability
ParameterValue
Durability (operating cycles, typ.)10 000 000
3RT1025-3KF40 — Environmental
ParameterValue
Operating temperature range-25 ... +60 °C
3RT1025-3KF40 — Mechanical
ParameterValue
Width45 mm
Height88 mm
Depth100 mm

Product details

This contactor is rated for motor duty: 7.5 kW at AC-2 (400 V) and 15.5 A at AC-4 (400 V). AC-2 covers slip-ring motor starting and reversing; AC-4 covers plugging and inching — the harder duty cycle. If you're switching a standard squirrel-cage motor on a pump or conveyor, those are the numbers that tell you whether it'll hold up. At 500 V it's good for 10 kW and at 690 V for 11 kW, so it spans common European voltage levels without derating surprises. The coil is a straight 110 V DC, pulling 4.2 W on both pick-up and hold. That constant-power coil means the control transformer or DC supply doesn't see a current spike on closure — useful when you're driving several contactors from one supply. The varistor across the coil clips the inductive kickback, which protects nearby PLC outputs and keeps the panel quiet. Mechanically, it's rated for 10 million typical operations, which is a long service life for a contactor this size.

Side-by-side mounting is allowed, which keeps the panel dense. The main circuit terminals accept solid or stranded wire: 2x (0.25 to 2.5 mm²) for the control circuit, and up to 2x 10 mm² or 1x 8 AWG for the power circuit. That's enough for the motor leads on a 7.5 kW load at 400 V. The front of the contactor is IP20 — safe to touch with tools — but the terminals are IP00, so live parts are exposed once the wire is landed. That's standard for panel-mount contactors; just means the panel door needs to be interlocked or the contactor placed behind a cover. That lets you choose between tighter protection or higher fault tolerance depending on the application.

Frequently asked questions

What are the key motor ratings for this contactor?

At 400 V, it's rated 7.5 kW in AC-2 duty and 15.5 A in AC-4 duty. At 500 V it handles 10 kW, and at 690 V it's good for 11 kW. The coil is 110 V DC with a built-in varistor suppressor.

Does the 3RT1025-3KF40 fit on a standard DIN rail?

Yes, it mounts on a 35 mm standard rail per DIN EN 50022, using either screws or the snap-on clip. Side-by-side mounting is permitted, and the S0 frame is 45 mm wide.

What wire sizes does this contactor accept?

The control circuit terminals accept 2x (0.25 to 2.5 mm²) solid or stranded. The main power terminals accept up to 2x 10 mm² or 1x 8 AWG. For AWG, that's 2x (16 to 12) or 2x (14 to 10) on the main contacts.

MPN
3RT1025-3KF40