Siemens 3RH2911-4FB22 Auxiliary Switch Block 2NO+2NC, Front Mount Original Brand New

Overview

The Siemens 3RH2911-4FB22 is a high-quality, front-mountable auxiliary switch block from the SIRIUS line, designed to expand the contact capabilities of SIRIUS 3RT2 power contactors and 3RH2 contactor relays.

This essential accessory features a 2 NO (Normally Open) + 2 NC (Normally Closed) contact configuration, providing a total of four auxiliary contacts. It utilizes a ring cable lug connection for robust and reliable wiring. Its design ensures quick and easy front snap-on mounting onto the compatible base units, making it ideal for control circuit applications, especially those requiring force-guided contacts for safety functions.

The unique contact path designation of 1 NO, 1 NC (instantaneous) and 1 NC (lagging), 1 NO (leading) allows for specific timing requirements in demanding control systems (Designation: 11 U, .3/.4, .1/.2, .5/.6, .7/.8).

Key Features / Specification

• Product ID: 3RH2911-4FB22
• Contact Configuration: 2 NO (Normally Open) + 2 NC (Normally Closed)
• Mounting: Front Snap-on Mounting
• Connection Type: Ring Cable Lug Connection (formerly terminal designation: 11 U, .3/.4, .1/.2, .5/.6, .7/.8)
• Contact Path: 1 NO Instantaneous, 1 NC Instantaneous, 1 NC Lagging, 1 NO Leading
• Compatibility: For SIRIUS Contactor Relays 3RH2 and Power Contactors 3RT2 (Sizes S00/S0)
• Rated Insulation Voltage: 690 V
• Application Suitability: Control Circuits, Safety Applications (often meets requirements for force-guided operation)

Benefit

• Enhanced Control: Easily expands the switching capacity of your 3RT2 contactors or 3RH2 relays, allowing for complex control and interlocking functions.
• Safety Compliance: The front auxiliary contacts often fulfill the characteristics of force-guided operation, making them suitable for safety-related applications as per IEC 60947-5-1
• Time-Saving Installation: Simple and quick snap-on mounting on the front of the base unit.
• Robust Connection: Secure ring cable lug terminals ensure a lasting and reliable electrical connection.
• Optimized Timing: Includes contacts with special timing characteristics (leading/lagging) for critical sequence control.

Function & Application

The 3RH2911-4FB22 auxiliary switch block is used to provide feedback signals and create interlocks within a control circuit. Its primary function is to multiply the control signals from the main contactor or relay.

Typical Applications Include:

1. Interlocking: Preventing two contactors from being energized simultaneously (e.g., in a reversing starter).
2. Status Indication: Providing signals to PLCs, indicator lights, or control panels to show the ON/OFF status of the main contactor.
3. Complex Control Schemes: Utilizing the leading and lagging contacts for sequence control, ensuring one function starts slightly before or after another.
4. Safety Circuits: Used in conjunction with safety relays where force-guided contacts are mandatory for monitoring machine guards and emergency stops.

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