Siemens 3RH1921-1DA11 Side-mounted Auxiliary Contact Block

Description

Siemens 3RH1921-1DA11 Side-mounted Auxiliary Contact Block

Product Dimensions：

The Siemens 3RH1921-1DA11 is a lateral (side-mounting) auxiliary switch block designed for use with Siemens SIRIUS 3RT1 contactors and 3RH1 contactor relays. It expands the control and signaling capabilities of contactors without adding depth to the installation.

Siemens 3RH1921-1DA11 Auxiliary Switch Block. 来源：eBay

Product Detailed Description

The 3RH1921-1DA11 features a 1 NO + 1 NC (1 Normally Open + 1 Normally Closed) contact configuration. Unlike front-mounting blocks that clip onto the face of a contactor, this unit clips onto the side (lateral mounting), making it an excellent solution when cabinet depth is limited. It provides reliable status feedback to PLCs, pilot lights, or secondary control circuits.

Technical Parameters

Product Advantages

• Space Optimization: Side mounting keeps the front profile of the contactor clear, preserving depth clearance in shallow control panels or enclosures.
• High Contact Reliability: Features self-cleaning contacts suitable for switching low voltages and low currents (e.g., direct PLC inputs).
• Easy Tool-Free Installation: Snaps directly onto the side of compatible 3RT1 power contactors (sizes S0 through S12) or 3RH1 contactor relays.
• Mechanically Linked Contacts: Ensures positively driven action, preventing the NO and NC contacts from closing simultaneously—a crucial feature for safety interlocks.

Important Considerations & Precautions

• Compatibility: Designed specifically for 3RT1 contactors and 3RH1 relays. For newer 3RT2 contactors, check compatibility with the 3RH29 accessory series.
• Mounting Limitations: Verify the available lateral space in your DIN rail layout, as adding side blocks increases the overall width of the contactor assembly.
• Terminal Torque: Tighten the screw terminals according to the manufacturer’s specified torque rating to prevent loose connections or terminal stripping.

Product Applications

• Status Feedback: Providing “ON/OFF” position status of a main contactor to a PLC or SCADA system.
• Control Interlocking: Mechanically interlocking two contactors (such as in a reversing starter setup) so both cannot be energized at the same time.
• Visual Indication: Directly driving panel indicator lights or audible alarms when a contactor state changes.

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