Siemens 3RH1921-2CA10 SIRIUS Auxiliary Switch, 1 NO, 10 A
Siemens SIRIUS 3RH1921-2CA10 front-side auxiliary switch, 1 NO contact, spring-loaded terminals, 10 A maximum, for 3RT1 contactors.
Specifications
| Parameter | Value |
|---|---|
| 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 |
| Parameter | Value |
|---|---|
| Auxiliary contact reliability | 1 faulty switching per 100 million (17 V, 1 mA) |
| Parameter | Value |
|---|---|
| Mounting method | snap-on mounting |
| Parameter | Value |
|---|---|
| Operating temperature range | -25 ... +60 °C |
| Storage temperature range | -55 ... +80 °C |
| Parameter | Value |
|---|---|
| Width | 10 mm |
| Height | 38 mm |
| Depth | 51 mm |
Product details
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.
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.