Siemens Auxiliary Switch 3RH2122-1FB40
Original price was: $61.72.$56.57Current price is: $56.57.
Short Description
Siemens SIRIUS 3RH2 Auxiliary Contactor Relay – Reliable Control Circuit Switching
Complete SIRIUS 3RH2 auxiliary contactor relay portfolio from Siemens. Available in 4-pole and 8-pole versions with contact configurations of 4 NO, 3 NO + 1 NC, and 2 NO + 2 NC. Compact S00 frame (45 mm width) for high-density control panels. Control voltage range 24 V to 230 V AC/DC. Rated insulation voltage 690 V, operational current up to 10 A (AC-12). Mechanical life of 30 million operating cycles. Available with screw, spring-loaded, or ring cable lug connections. Coupling relay variant available for direct PLC interface with integrated varistor. Ideal for control circuit switching, signal multiplication, interlocking, and PLC output coupling in industrial automation and motor control centers.
Siemens SIRIUS 3RH2 Auxiliary Contactor Relay
| Feature / Specification | Details |
|---|---|
| Product Family | SIRIUS 3RH2 Contactor Relay |
| Product Type | Auxiliary Contactor Relay |
| Frame Size | S00 (45 mm width) |
| Pole Configurations | 4-pole (3RH21), 8-pole (3RH22), 2 NO + 2 NC |
| Control Voltage Range | 24 V to 230 V AC/DC (preferred voltages) |
| Rated Insulation Voltage | 690 V |
| Rated Surge Voltage | 6 kV |
| Contact Rating (AC-12) | 10 A max |
| Contact Rating (AC-15) | 10 A at 230 V; 3 A at 400 V; 1 A at 690 V |
| Mechanical Life | 30,000,000 operating cycles |
| Terminal Types | Screw, spring-loaded, ring cable lug |
| Protection Class | IP20 |
| Ambient Temperature | -25°C to +60°C (operation) |
| Mounting | 35 mm DIN rail or screw mounting |
Typical Applications & Industries:
✓ Control circuit switching and amplification ✓ Signal multiplication and isolation
✓ PLC output coupling (coupling relays) ✓ Interlocking and logic control
✓ Machine tool and automation panels ✓ Motor control centers (MCC)
Detailed Description – Siemens SIRIUS 3RH2 Auxiliary Contactor Relay
1. Series Overview – Reliable Control Circuit Switching
The SIRIUS 3RH2 is a contactor relay designed specifically for switching in the auxiliary and control circuits of industrial electrical systems. Unlike power contactors that switch main loads, the 3RH2 handles the lower-power signals that control, interlock, and monitor machinery .
The 3RH2 portfolio covers 4-pole (3RH21) and 8-pole (3RH22) versions, with contact configurations including 4 NO, 3 NO + 1 NC, and 2 NO + 2 NC . All versions share the compact S00 frame size (45 mm width), making them ideal for high-density control panels .
2. Key Features
High Contact Reliability – The 3RH2 relays feature gold-plated or bifurcated contacts on select models, ensuring reliable switching even at low voltages and currents (17 V, 1 mA) . This makes them suitable for PLC interface applications.
Wide Voltage Range – The operating mechanisms are available for AC and DC control voltages from 24 V to 230 V, with preferred voltage versions stocked for rapid delivery .
Modular Expansion – The 3RH2 can be expanded with front-mounting auxiliary switch blocks (3RH29 series), adding up to 4 additional contacts without increasing the device width .
Robust Construction – With a mechanical service life of 30 million operating cycles, the 3RH2 is built for continuous industrial duty .
3. Technical Specifications
| Parameter | Specification |
|---|---|
| Size | S00 (45 mm width) |
| Pole Configurations | 4-pole, 8-pole |
| Rated Insulation Voltage | 690 V (pollution degree 3) |
| Rated Surge Voltage | 6 kV |
| Operational Current (AC-12) | 10 A max |
| Operational Current (AC-15) | 10 A at 230 V; 3 A at 400 V; 1 A at 690 V |
| Operational Current (DC-12, 1 path) | 10 A at 24 V; 3 A at 110 V; 1 A at 220 V |
| Mechanical Life | 30,000,000 operating cycles |
| Closing Delay (AC) | 8–33 ms |
| Opening Delay (AC) | 4–15 ms |
4. Connection Systems
The 3RH2 is available with three connection technologies to match any wiring requirement :
| Connection Type | Availability |
|---|---|
| Screw connection | ✓ Standard |
| Spring-loaded connection | ✓ Vibration-proof, maintenance-free |
| Ring cable lug connection | ✓ For high-reliability applications |
5. Coupling Relay Variant (3RH2 for PLC)
A specialized coupling relay variant (e.g., 3RH2122-2LV40) is available for direct interface with PLC outputs. This version features :
Integrated varistor for surge suppression
Extended operating range: 0.7–1.25 × Us
DC control voltage: 36 V DC (and other options)
Not expandable with auxiliary switches (compact, fixed configuration)
Selection Guide – Understanding the Naming Convention (Siemens 3RH2)
Part Number Format: 3RH2 [Pole Code] [Contact Code] - [Terminal] [Voltage Code]
Example: 3RH2122-2AP60
| Code Position | Meaning | Options |
|---|---|---|
| 3RH2 | Product family: Contactor relay | 3RH2 |
| 1 | Pole count | 1 = 4-pole, 2 = 8-pole |
| 2 | Contact configuration | 2 = 2 NO + 2 NC, 3 = 3 NO + 1 NC, 4 = 4 NO |
| 2 | Design variant | (varies) |
| -2 | Terminal type | 1 = Screw, 2 = Spring-loaded |
| AP | Voltage code | AP = 220 V AC 50 Hz / 240 V AC 60 Hz |
| 60 | Frequency | 60 = 60 Hz, 50 = 50 Hz |
Model Decoder Examples:
| Model Number | Decoding |
|---|---|
| 3RH2122-2AP60 | 8-pole, 2 NO + 2 NC, spring-loaded terminal, 220 V AC 50 Hz / 240 V AC 60 Hz |
| 3RH2122-2LV40 | 8-pole, 2 NO + 2 NC, spring-loaded terminal, 36 V DC coupling relay with varistor |
| 3RH2122-1AG60 | 8-pole, 2 NO + 2 NC, screw terminal, 100 V AC 50 Hz / 100-110 V AC 60 Hz |
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