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Siemens 3RH1921-2CA10 — Contactors

Siemens 3RH1921-2CA10 SIRIUS Auxiliary Switch, 1 NO, 10 A

MPN3RH1921-2CA10
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Siemens SIRIUS 3RH1921-2CA10 front-side auxiliary switch, 1 NO contact, spring-loaded terminals, 10 A maximum, for 3RT1 contactors.

$5.10Ref. price · indicative, final on quote
Siemens 3RH1921-2CA10 datasheet (PDF)
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

3RH1921-2CA10 — Ratings & Performance
ParameterValue
Rated value @ 24 V10 A
Rated value @ 60 V4.7 A
Rated value @ 110 V3 A
Rated value @ 220 V1.2 A
3RH1921-2CA10 — Contacts & Poles
ParameterValue
Auxiliary contact reliability1 faulty switching per 100 million (17 V, 1 mA)
3RH1921-2CA10 — Connection & Mounting
ParameterValue
Mounting methodsnap-on mounting
3RH1921-2CA10 — Environmental
ParameterValue
Operating temperature range-25 ... +60 °C
Storage temperature range-55 ... +80 °C
3RH1921-2CA10 — Mechanical
ParameterValue
Width10 mm
Height38 mm
Depth51 mm

Product details

What the 10 A rating means for your control circuit

The 3RH1921-2CA10 is a front-side auxiliary switch block rated 10 A maximum — that's the thermal current (Ith) the contacts can carry continuously. Always size the auxiliary contact to the coil inrush of the device it's driving, not the thermal rating. That matters when the auxiliary feeds a 24 VDC digital input card.

Snap-on mounting and spring terminals

This auxiliary switch snaps onto the front of a 3RT1 contactor — the 'with 3RT1' note in the spec is the compatibility key. No DIN rail, no separate bracket; it clips directly to the contactor's front face. The 10 mm width means it adds almost no footprint to the contactor assembly. The IP20 front protection means finger-safe when installed in a closed panel — no special cover needed for the terminal area.

Frequently asked questions

What does 'with 3RT1' mean in the spec?

The 'with 3RT1' note means this front-side auxiliary switch is designed to mount directly onto Siemens 3RT1 series contactors. It clips onto the contactor's front face without needing a separate DIN rail bracket.

Will the 3RH1921-2CA10 drop into a panel wired for a 3RH2131-1AH00?

The 3RH2131-1AH00 is a different auxiliary switch block with different contact configuration and terminal layout. The 3RH1921-2CA10 is a 1 NO spring-terminal block for 3RT1 contactors; the 3RH2131-1AH00 is a screw-terminal block for a different contactor series. They are not direct drop-in replacements — check the contactor model and wiring scheme before substituting.

MPN
3RH1921-2CA10