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Siemens 3RH2122-2BA40 SIRIUS Auxiliary Contactor, S00, 2 NO

MPN3RH2122-2BA40

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Siemens SIRIUS 3RH2122-2BA40 auxiliary contactor, size S00, 2 NO instantaneous contacts, screw and snap-on mounting on 35 mm DIN rail, 73 x 45 x 70 mm.

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Siemens 3RH2122-2BA40 datasheet (PDF)

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

Specifications

3RH2122-2BA40 — Identification
Parameter	Value
Contactor frame size	S00

3RH2122-2BA40 — Ratings & Performance
Parameter	Value
Rated operational current, AC-12, max.	10 A
Rated value @ 400 V	3 A
Rated value @ 500 V	2 A
Rated value @ 690 V	1 A
Rated value @ 230 V	10 A
Rated value @ 24 V	10 A
Rated value @ 60 V	4.7 A
Rated value @ 110 V	3 A
Rated value @ 220 V	1.2 A

3RH2122-2BA40 — Control & Coil
Parameter	Value
Control supply voltage type	DC

3RH2122-2BA40 — Contacts & Poles
Parameter	Value
Auxiliary contact reliability	1 faulty switching per 100 million (17 V, 1 mA)

3RH2122-2BA40 — Connection & Mounting
Parameter	Value
Conductor cross-section, solid or stranded	2x (0,5 ... 4 mm²)
Conductor cross-section, finely stranded w/ ferrule	2x (0.5 ... 2.5 mm²)
Mounting method	screw and snap-on mounting onto 35 mm standard mounting rail

3RH2122-2BA40 — Durability
Parameter	Value
Durability (operating cycles, typ.)	30 000 000
Durability with aux. switch block (cycles, typ.)	10 000 000

3RH2122-2BA40 — Environmental
Parameter	Value
Operating temperature range	-25 ... +60 °C
Storage temperature range	-55 ... +80 °C
Installation altitude, max.	2 000 m

3RH2122-2BA40 — Mechanical
Parameter	Value
Width	45 mm
Height	70 mm
Depth	73 mm

3RH2122-2BA40 — Specifications
Parameter	Value
At AC	10 000 1/h

Product details

The 3RH2122-2BA40: At 400 V AC, the 3 A switching capacity suits it for isolating smaller contactor coils or indicator loads; the DC ratings drop sharply above 60 V due to arc extinction limits, so at 600 V DC it manages only 0.26 A.

Wiring and compliance

The auxiliary switch extension is supported (product extension auxiliary switch: yes), allowing field addition of extra contact blocks without removing the contactor from the rail. RoHS compliance effective from 10 January 2009 (substance prohibitance date), and the product carries the SIRIUS brand designation for full traceability to Siemens industrial catalog.

Frequently asked questions

What is the 3RH2122-2BA40 used for?

It is an auxiliary contactor for control-circuit switching — typically used to interlock contactor coils, route PLC digital outputs to motor starters, or provide additional NO contacts in a SIRIUS S00 starter assembly.