Siemens SIRIUS 3RH1921-1EA02 Auxiliary Switch Block, 2NC Contacts, Lateral Mount, Screw Terminal, For 3RT1 Contactors Original Brand New

Overview: Siemens SIRIUS 3RH1921-1EA02 Auxiliary Switch

The Siemens 3RH1921-1EA02 is a high-quality, laterally mountable auxiliary switch block designed specifically for expanding the auxiliary contact capability of the Siemens SIRIUS 3RT1 Contactor series (Sizes S0 to S12). This essential component of the SIRIUS modular system provides reliable status signaling and control circuit functions.

It features two Normally Closed (2NC) instantaneous auxiliary contacts, making it ideal for interlocking, signaling, and control functions where a closed circuit during the contactor’s rest position is required. Installation is quick and tool-free thanks to its snap-on mounting mechanism to the side of the main contactor. The screw terminals ensure robust and secure electrical connections in industrial control panels.

Key Benefit

• System Expansion: Easily adds 2 Normally Closed (2NC) auxiliary contacts to your main 3RT1 contactor, increasing control flexibility.
• Time-Saving Installation: Features a lateral snap-on mounting design for quick, tool-free attachment and removal.
• Reliable Connections: Equipped with secure screw terminals for long-term operational integrity in demanding industrial environments.
• SIRIUS Quality: Part of the globally recognized Siemens SIRIUS modular system, ensuring high mechanical and electrical endurance (e.g., 10 million mechanical operating cycles typical).
• Safety Functionality: Functions as a Mirror Contact according to IEC 60947-4-1 (in combination with the 3RT1 contactor).

Function

The auxiliary switch block operates in sync with the main contactor’s armature. When the contactor coil is energized, the 2NC contacts open, signaling the operational status to the control circuit (e.g., PLC or relays).

Application

The 3RH1921-1EA02 is primarily used in control panels, motor starters, and automation systems for:

• Status indication (contactor ON/OFF).
• Electrical interlocking of contactors.
• Switching of small control loads (AC-15, DC-12/13).
• Feedback loops in complex control circuits.

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