Overview
The Siemens 3RH2921-1DA20 auxiliary switch is a high-quality, lateral auxiliary switch designed to enhance the functionality of Siemens contactors and relays. This switch features 2 NO (Normally Open) contacts with clearly labeled connections: left side (53/54, 63/64) and right side (33/34, 43/44), providing a reliable and organized current path.
Engineered for use with 3RT2 contactors and 3RH2 contactor relays, it comes equipped with screw terminals for secure and easy installation. Its durable design ensures long-lasting performance in industrial and commercial electrical systems, making it a dependable choice for professional electricians and automation engineers.
Key Benefit
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Reliable Performance: Provides consistent switching for contactors and relays.
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Easy Installation: Screw terminals allow quick and secure mounting.
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Versatile Compatibility: Works seamlessly with 3RT2 contactors and 3RH2 relays.
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Compact Lateral Design: Optimizes space in control panels.
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Durable Construction: Ensures long-lasting industrial use.
Function & Application
The 3RH2921-1DA20 auxiliary switch acts as an electrical signal repeater, mirroring the state of the main contactor. It is typically used for:
- Signaling: Providing visual indication (e.g., pilot lights) or electrical feedback to a PLC/control system when the contactor is energized.
- Interlocking: Creating safety circuits, such as an electrical interlock, to prevent simultaneous operation of two contactors (e.g., in a reversing starter).
- Control Logic: Expanding the number of auxiliary contacts for complex control schemes in motor starters, heating systems, and general industrial automation.
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