Description

This Siemens auxiliary switch block is a modular expansion component designed to provide additional signaling and control capabilities for primary switching devices, such as 3RT contactors or 3RH modular relays within the Siemens SIRIUS range.

Functional Overview:

• Contact Configuration: 4NO (4 Normally Open). This means the unit contains four independent sets of contacts that remain open in the de-energized state and close simultaneously when the main device is actuated.
• Purpose: It acts as a “link” between the high-power circuit and the control system. While the main contactor switches the motor or load, this auxiliary block provides feedback to PLCs, activates indicator lights, or manages electrical interlocking.

Key Technical Features:

• Mounting Type: Typically available as a front-mounted (snaps onto the face of the contactor) or side-mounted version, saving space on the DIN rail.
• High Reliability: Designed with high contact stability, making it suitable for switching low voltages and currents used in electronic control circuits.
• Connection Technology: Usually available with either screw terminals for traditional wiring or spring-loaded terminals for vibration resistance and faster installation.

Common Applications:

• Status Feedback: Notifying a PLC or control room that a specific motor or heater is engaged.
• Logic Interlocking: Ensuring that two contactors cannot be closed at the same time (e.g., in a forward/reverse motor starter).
• Parallel Signaling: Simultaneously turning on a cooling fan or a “Running” pilot light when the main load is powered.
• Technical Tip: Ensure the auxiliary block’s part number matches your specific frame size (e.g., S00, S0, S2), as mounting clips vary between different sizes of Siemens contactors.