3RA2934-2B

The Siemens 3RA2934-2B is a mechanical interlocking device from the SIRIUS 3RA29 series. It is suitable for contactors of S2 and S3 sizes and is installed between two side-by-side contactors. Its purely mechanical structure ensures that only one contactor can be engaged at any given time. It is commonly used in forward and reverse starters or dual-circuit switching applications to improve system operational safety.

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Siemens 3RA2934-2B SIRIUS mechanical interlock device S2/S3

Product Positioning

The 3RA2934-2B is a purely mechanical interlocking device installed between two side-by-side SIRIUS contactors. It is suitable for S2 and S3 sizes and uses structural latches to ensure that the two contactors will not engage simultaneously. Compared to relying solely on electrical interlocking circuits, mechanical interlocking can maintain safety protection even when the control circuit malfunctions, making it a key safety component in the design of forward and reverse starters.

Core Product Advantages and Features

Purely mechanical interlock

The structural locking mechanism prevents two contactors from engaging simultaneously, without relying on electrical signals.

Applicable to S2 and S3 sizes

Compatible with contactor mounting on SIRIUS S2 or S3 frames.

Enhance security redundancy

Provides an additional layer of mechanical protection beyond electrical interlocking.

Installed between contactors

It is directly clipped into the middle position of two side-by-side contactors.

Commonly used in forward and reverse starters

It is a common safety accessory in the design of reversible motor starters.

project	Specification
Product Type	Mechanical interlocking device
Applicable size	S2, S3
Applicable series	SIRIUS 3RA29 series
net weight	Approximately 37.6 grams

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