Skip to main content
Siemens 3RT2018-4KB42-0LA0 — Contactors

Siemens SIRIUS 3RT2018-4KB42-0LA0 Contactor, Size S00, 24 VD

MPN3RT2018-4KB42-0LA0

Siemens SIRIUS contactor, Size S00, 3RT2018-4KB42-0LA0, 24 VDC coil with ring cable lug, extended operating range, screw and snap-on 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

3RT2018-4KB42-0LA0 — Identification
ParameterValue
Contactor frame sizeS00
3RT2018-4KB42-0LA0 — Ratings & Performance
ParameterValue
Rated operational current, AC-12, max.10 A
Rated operational current, AC-4 @ 400 V11.5 A
Rated value @ 400 V3 A
Rated value @ 500 V2 A
Rated value @ 690 V1 A
Rated value @ 230 V2 hp
Rated value @ 24 V10 A
Rated value @ 60 V2 A
Rated value @ 110 V1 A
Rated value @ 220 V0.3 A
3RT2018-4KB42-0LA0 — Control & Coil
ParameterValue
Control supply voltage typeDC
3RT2018-4KB42-0LA0 — Contacts & Poles
ParameterValue
Main poles3
Main NO contacts3
3RT2018-4KB42-0LA0 — Protection & Coordination
ParameterValue
Short-circuit coordination type 1, fusegG: 50A (690V,100kA), aM: 25A (690V,100kA), BS88: 50A (415V,80kA)
Short-circuit coordination type 2, fusegG: 25A (690V,100kA), aM: 20A (690V,100kA), BS88: 25A (415V,80kA)
Aux. switch short-circuit protection, fusegG: 10 A (500 V, 1 kA)
3RT2018-4KB42-0LA0 — Connection & Mounting
ParameterValue
Main circuit connectionRing cable lug connection
Aux. / control circuit connectionring terminal lug connection
Conductor cross-section, solid2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²), 2x 4 mm²
Mounting methodscrew and snap-on mounting onto 35 mm standard mounting rail according to DIN EN 60715
Side-by-side mountingYes
3RT2018-4KB42-0LA0 — Durability
ParameterValue
Durability (operating cycles, typ.)30 000 000
Durability with aux. switch block (cycles, typ.)10 000 000
3RT2018-4KB42-0LA0 — Environmental
ParameterValue
Operating temperature range-40 ... +70 °C
Storage temperature range-55 ... +80 °C
Installation altitude, max.2 000 m
3RT2018-4KB42-0LA0 — Mechanical
ParameterValue
Width45 mm
Height61 mm
Depth117 mm

Product details

It has an extended operating range with a pickup threshold of 0.7 times rated value. Physically it's compact: 45 mm wide, 61 mm tall, 117 mm deep. That puts it in the standard S00 footprint that fits tightly packed DIN-rail enclosures. Mounting is via screw or snap-on onto 35 mm rail per DIN EN 60715, and side-by-side mounting is allowed with the specified clearances — 10 mm upward, 10 mm forward, 10 mm downward, 6 mm at the side.

What the DC switching ratings mean for your load

This contactor carries a full set of DC-1 / DC-13 style switching ratings across the voltage range, and the values tell you exactly what it can break without welding contacts. At 24 V DC it's rated 10 A — that's the sweet spot for most control and small DC motor loads. At 48 V and 60 V it drops to 2 A, at 110 V to 1 A, at 220 V to 0.3 A, and at 690 V to 1 A. The 480 V and 600 V entries (14 A and 11 A respectively) look like AC ratings — likely AC-3 motor duty — so don't confuse those with DC interrupt capability at those voltages. That's fast enough for most interlocking and sequencing circuits, but if you're paralleling contacts for higher DC current, account for the total arcing energy across the gap.

The auxiliary switch is integrated (yes), so there's no separate add-on block to order for basic status feedback.

The coil connection uses a ring cable lug. The main power terminals accept solid conductors: 2x 0.5 to 1.5 mm², 2x 0.75 to 2.5 mm², or 2x 4 mm². That helps when you're fitting it into a crowded panel or a non-standard orientation.

Frequently asked questions

What are the key dimensions of this contactor?

Width is 45 mm, height is 61 mm, depth is 117 mm. That's the standard S00 footprint.

What wire sizes does the main terminal accept?

Solid conductors: 2x 0.5 to 1.5 mm², 2x 0.75 to 2.5 mm², or 2x 4 mm².

Will this contactor work in a panel designed for 3RT2026-4BB40?

No — the 3RT2026-4BB40 is Size S0, which has a different width and mounting footprint. The 3RT2018-4KB42-0LA0 is Size S00. You would need to re-drill the mounting rail or use an adapter plate, and the busbar system would not align.

MPN
3RT2018-4KB42-0LA0