3RH1921-2FA31 SIEMENS

3RH1921-2FA31 Siemens Basis unit

Brand：SIEMENS Model number：3RH1921-2FA31

Country of origin: Germany Product weight：0.55kg

HS code：8517623990

Inquire Now

Product Details：

Product Dimensions：

The 3RH1921-2FA31 belongs to the SIRIUS 3RH19 accessory range. It is a front-mounting auxiliary switch block, meaning it snaps directly onto the face of a compatible 3RT1 power contactor (sizes S00 through S3) or 3RH1 contactor relay. This specific model features a 4-pole configuration utilizing spring-loaded terminals (Cage Clamp technology), which offer superior vibration resistance compared to standard screw terminals. The internal contact arrangement consists of 3 Normally Open (NO) and 1 Normally Closed (NC) contacts. Its design ensures positive-driven contact operation, making it suitable for safety-related feedback loops.

Product Parameters

Product Brand Name: SIRIUS
Product Designation: Auxiliary switch block
Suitability for Use: For contactor relays and power contactors (3RH1 and 3RT1)
Contact Configuration: 3 NO + 1 NC (3 Normally Open / 1 Normally Closed)
Connection Method: Spring-loaded terminals (Cage Clamp)
Number of Poles: 4 poles
Operating Current at AC-15: Typically $6 \text{ A}$ at $24 \text{ V}$ , $6 \text{ A}$ at $230 \text{ V}$ , and up to $3 \text{ A}$ at $400 \text{ V}$
Operating Current at DC-13: Approximately $6 \text{ A}$ at $24 \text{ V}$ , $0.3 \text{ A}$ at $220 \text{ V}$ , and $0.1 \text{ A}$ at $600 \text{ V}$
Insulation Voltage: $690 \text{ V}$ rated value
Surge Voltage Resistance: $6 \text{ kV}$ rated value
Mechanical Endurance: Approximately 10 million operating cycles
Ambient Temperature: Operating limits between $-25\text{°C}$ and $60\text{°C}$ ( $-13\text{°F}$ to $140\text{°F}$ )
Protection Class: IP20 on the front side

Product Advantages

A major benefit of the 3RH1921-2FA31 is its Spring-Loaded Terminal Technology. This design maintains a constant clamping force on the wire, completely eliminating the need for periodic retightening and making it ideal for high-vibration industrial environments. The Snap-On Mounting System allows for tool-free installation directly onto the front of the contactor, which minimizes assembly time during panel building.

The High Contact Reliability ensures that even low-voltage, low-current signals (such as those entering electronic PLC inputs) are switched cleanly without oxidation interference. Additionally, the Mirrored Contact Design ensures that the NC contact cannot be closed simultaneously with a power contact if a fault occurs, facilitating compliant safety feedback signals.

Important Considerations and Precautions

When installing the 3RH1921-2FA31, ensure that the Front Face of the Host Contactor is Clean and free of debris before snapping the block into place, as alignment offsets can prevent the mechanical actuator from engaging correctly. While spring-loaded terminals accept both solid and stranded wires, it is important to use the Correct Screwdriver Size to open the cage clamp during wiring to avoid damaging the internal spring mechanism.

Be aware of Contact Electrical Ratings; exceeding the AC-15 or DC-13 current limits can cause contact welding or premature degradation of the switching face. When deploying the block in safety circuits, always verify that the configuration aligns with the mirror-contact or force-guided parameters specified in your safety system documentation. Lastly, ensure that the Total Power Dissipation and Space within the enclosure allow for adequate heat migration, especially when multiple auxiliary blocks are stacked in high-ambient control cabinets.

Product Applications

The Siemens 3RH1921-2FA31 is widely integrated into industrial control panels where auxiliary logic state tracking is necessary.

Motor Control Centers (MCCs): Providing status feedback (On/Off/Fault) from main motor starters to centralized control rooms or PLC inputs.
Safety Interlocking Circuits: Utilizing the NC contact to monitor contactor state within safety relays or modular safety controllers to prevent hazardous restarts.
Control Relay Multiplication: Expanding the number of available contacts in a complex control relay array for sequencing operations.
Material Handling Systems: Signalling conveyor belt status, gate positions, and diversion arm activations via auxiliary routing lines.
HVAC Infrastructure: Interlocking compressor contactors with fan motor contactors to ensure correct system operational sequences.

6ES7972-0CB20-0XA0 SIEMENS

We have the same series of models in stock. If you don't find the model you need, please contact us and we will provide you with an official quotation！

SIEMENS6SE6440-2UD13-7AA1

SIEMENS6SL3224-0BE37-5AA0

SIEMENS6DD1684-0BC0

SIEMENS6DD1684-0AH0

SIEMENS6AV6542-0CA10-0AX0

SIEMENS3RT1044-1AG20

SIEMENS6AV6647-0AH11-3AX0

SIEMENS3RT2017-1AF01

SIEMENS6ES7321-1CH20-0AA0

SIEMENS6ES7331-7HF01-0AB0

SIEMENS6ES7195-7HA00-0XA0

SIEMENS6SE70386GL841JA1