3RH2122-1JB40
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Siemens 3RH2 Series
806 variants · Siemens
Siemens 3RH2 — SIRIUS Auxiliary Relay for Control Signal Switching and Contact Multiplication
The Siemens 3RH2 series is the S0 frame auxiliary relay in the SIRIUS switching device family, providing up to 8 contacts (4NO+4NC) for control signal switching, contact multiplication, and signal isolation. With over 800 variants, the 3RH2 extends the auxiliary relay concept to higher contact counts than the S00 frame 3RH1.
3RH2 vs 3RH1
| Feature | 3RH1 (S00) | 3RH2 (S0) |
|---|---|---|
| Frame size | S00 (45mm) | S0 (55mm) |
| Max contacts | 4NO+4NC | 4NO+4NC |
| Rated thermal current | 10A | 10A |
| Larger terminals | No | Yes (for multiple conductors) |
Select 3RH2 when the larger terminal capacity is required for multiple conductor connections or when all relays in the panel are S0 frame for uniformity with 3RT2 contactors.
Applications
- Contact Multiplication: A single PLC output drives multiple relay coils or contactor coils via 3RH2 contacts, providing galvanic isolation between the PLC and load circuits.
- Signal Level Adaptation: Convert a 24V DC control signal to switch a 230V AC annunciator or status lamp circuit.
- Safety-Related Circuits: Positively-driven contacts for feedback circuits in safety-related control systems.
Availability
3RH2 auxiliary relays: broadly stocked at Siemens distributors.
About the Siemens 3RH2 Series
The Siemens 3RH2 Series series groups 806 related part numbers, each listed with full specifications, a datasheet where available, and an RFQ option. The listed variants share a common arcing time of 10 ... 15 ms. Variants differ by depth, height and width, so you can match the exact depth your application requires using the selection guide below.
Select a variant by
- Depth
- 73 mm · 117 mm
- Height
- 57.5 mm · 70 mm
- Width
- 45 mm · 90 mm
Shared specifications
- Arcing time
- 10 ... 15 ms
Variant comparison
| Parameter | 3RH2140-1AP00 | 3RH2422-1AK60 | 3RH2253-1BB40 | 3RH2122-1KB40 | 3RH2244-4AK60 | 3RH2244-4BG40 |
|---|---|---|---|---|---|---|
| Depth | 73 mm | 73 mm | 117 mm | 73 mm | 117 mm | 117 mm |
| Height | 57.5 mm | 57.5 mm | 57.5 mm | 57.5 mm | 57.5 mm | 57.5 mm |
| Width | 45 mm | 90 mm | 45 mm | 45 mm | 45 mm | 45 mm |
Request a quote on any Siemens 3RH2 Series part number and we confirm price, availability and lead time per line — including end-of-life and allocation-constrained variants.
