Siemens 3RH1921-1KA11 Side-mounted Auxiliary Contact Block 1NO+1NC

Description

Siemens 3RH1921-1KA11 Side-mounted Auxiliary Contact Block 1NO+1NC

Product Dimensions：

The Siemens 3RH1921-1KA11 is a side-mounting Auxiliary Switch Block designed for the SIRIUS 3RT1 contactor and 3RH1 contactor relay family (specifically size S00 to S3). It expands the control signal capability of contactors without taking up valuable panel depth.

Product Detailed Description

The 3RH1921-1KA11 snaps directly onto the side of a SIRIUS contactor. It contains two auxiliary contacts: 1 Normally Open (1 NO) and 1 Normally Closed (1 NC). It uses standard screw terminals for wiring and incorporates force-guided (positively driven) contacts, making it suitable for safety monitoring circuits where contact state feedback is required.

Technical Parameters

Product Advantages

• Space-Saving Design: Mounting to the side keeps the front profile clear, ideal for shallow cabinets where front-mounted accessories might interfere with door clearance.
• Positive Guidance / Safety Ratings: Features positively driven contacts according to IEC 60947-5-1, ensuring the NO and NC contacts cannot both be closed at the same time—essential for safety-related feedback loops.
• Tool-Free Installation: Snaps easily onto the side of compatible contactors without needing additional screws or mounting hardware.
• High Switching Reliability: Features self-cleaning contacts designed to maintain electrical continuity even under low-current, low-voltage control signals.

Important Considerations (Precautions)

• Contactor Series Compatibility: This module belongs to the 3RT1 / 3RH1 generation. If you are using the newer 3RT2 / 3RH2 SIRIUS Modular System, verify mechanical fit—3RT2 contactors typically use the 3RH2911 accessory series.
• Side-Mounting Limits: Most SIRIUS contactors allow only one side-mounted auxiliary block on each side (left/right). Check the maximum allowable auxiliary contact combination in the Siemens catalog for your specific contactor frame size.
• Wiring Tightening Torque: Always adhere to the recommended screw terminal torque (0.8 to 1.2 N\cdotm) to ensure a solid connection without stripping the housing.

Product Applications

• Contactor State Interlocking: Providing electrical interlocking between two contactors (e.g., reversing starter circuits using the 1 NC contact).
• PLC Signal Feedback: Feeding the contactor’s actual operational status back to a PLC input module via the 1 NO contact.
• Status Indication: Driving panel door indicator lights or remote alarms to show when a motor circuit is energized or tripped.
• Safety Circuits: Used in safety feedback loops to monitor whether a main power contactor has successfully opened upon a safety trip request.

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