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Siemens 3RH2122-4KB40-0LA0 — Contactors

Siemens 3RH2122-4KB40-0LA0 SIRIUS Auxiliary Contactor, 24 VD

MPN3RH2122-4KB40-0LA0

Siemens SIRIUS auxiliary contactor, size S00, 24 VDC coil with integrated suppressor diode, 2 NO instantaneous contacts, screw and snap-on mounting on 35 mm DIN rail, 117 mm depth, 45 mm width.

Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

3RH2122-4KB40-0LA0 — Identification
ParameterValue
Contactor frame sizeS00
3RH2122-4KB40-0LA0 — Ratings & Performance
ParameterValue
Rated operational current, AC-12, max.10 A
Rated value @ 400 V3 A
Rated value @ 500 V2 A
Rated value @ 690 V1 A
Rated value @ 230 V10 A
Rated value @ 24 V10 A
Rated value @ 60 V4.7 A
Rated value @ 110 V3 A
Rated value @ 220 V1.2 A
3RH2122-4KB40-0LA0 — Control & Coil
ParameterValue
Control supply voltage typeDC
3RH2122-4KB40-0LA0 — Contacts & Poles
ParameterValue
Auxiliary contact reliability1 faulty switching per 100 million (17 V, 1 mA)
3RH2122-4KB40-0LA0 — Connection & Mounting
ParameterValue
Mounting methodscrew and snap-on mounting onto 35 mm DIN rail
3RH2122-4KB40-0LA0 — Durability
ParameterValue
Durability (operating cycles, typ.)30 000 000
Durability with aux. switch block (cycles, typ.)10 000 000
3RH2122-4KB40-0LA0 — Environmental
ParameterValue
Operating temperature range-40 ... +70 °C
Storage temperature range-55 ... +80 °C
Installation altitude, max.2 000 m
3RH2122-4KB40-0LA0 — Mechanical
ParameterValue
Width45 mm
Height57.5 mm
Depth117 mm
3RH2122-4KB40-0LA0 — Specifications
ParameterValue
At AC10 000 1/h

Product details

The S00 frame is 45 mm wide, 57.5 mm tall, and 117 mm deep, so it fits the standard S00 footprint that shares the same rail spacing as the 3RT2 contactors.

The 2 NO contacts are rated for AC switching at 10 000 operations per hour, with an arcing time of 10 to 15 ms. DC switching is specified at 7 to 20 ms. The contacts handle a range of voltages: 10 A at 24 V AC, 10 A at 230 V AC, 3 A at 400 V AC, and 1 A at 690 V AC. For DC loads, the ratings drop — 4.7 A at 60 V, 3 A at 110 V, 1.2 A at 220 V, 0.5 A at 440 V, and 0.26 A at 600 V. That's typical for a S00 auxiliary contactor; the DC derating is steep because DC arcs don't self-extinguish at zero-crossing.

Coil and environmental specs

The 24 VDC coil draws 13 W on pickup and 4 W holding — the holding power is low enough that a standard 24 VDC power supply can keep it energized continuously without overheating. Operating temperature range is -40 to +70 °C, storage is -55 to +80 °C, with relative humidity minimum 10 %.

Frequently asked questions

Where can I buy 3RH2122-4KB40-0LA0 and get a price?

This part is sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time — submit an RFQ for a firm price and lead time.

Will 3RH2122-4KB40-0LA0 drop into a panel specified around 3RH2122-1BA40 without rewiring?

Both are S00 frame auxiliary contactors with the same DIN rail footprint and 45 mm width, so the mechanical fit is identical. The difference is the coil voltage — 3RH2122-4KB40-0LA0 has a 24 VDC coil with an integrated suppressor diode, while the 1BA40 variant uses a different coil voltage. If the panel was wired for a 24 VDC coil, this part drops in without rewiring. Verify the coil voltage matches your control circuit before swapping.

MPN
3RH2122-4KB40-0LA0