Siemens 3RH29112XA200MA0 Auxiliary Switch Block
Application Context and Function
Auxiliary switch blocks attach to the front face of 3RH coupling relays and 3RT contactors in the Siemens SIRIUS modular system. The 3RH29112XA200MA0 adds two normally-open (2NO) auxiliary contacts to a contactor or relay base unit, enabling auxiliary control-circuit signaling and coil-control interlocking without replacing the power-switching device.
The block ships as a boxed unit (encapsulation: Box) with Active product status and ROHS3 Compliant designation.
Contact Configuration and Compatibility
Contact Arrangement
The primary unit carries two normally-open contacts. The contact function is fixed by the mechanical design of the block; no field adjustment of NO/NC allocation is listed in the catalog records for this specific MPN.
Compatible Device Series
All parts in this catalog group share the same compatibility scope: 3RH (coupling/interface relays) and 3RT (contactors). The base product prefix 3RH29112 identifies the mounting interface standard.
Catalog Comparison — Contact Variants
The 3RH29112 base series offers multiple contact-arrangement options. Comparison rows below show the in-catalog alternatives sharing the same base product, accessory type, series, and package. Similarity scores reflect parametric proximity only; they are not interchange endorsements.
| MPN | Contact Arrangement | Similarity |
|---|---|---|
| 3RH29112XA400MA0 | 4NO | 0.95 |
| 3RH29112XA310MA0 | 3NO+1NC | 0.95 |
| 3RH29112XA200MA0 | 2NO (primary) | — |
| 3RH29112XB220MA0 | 2NO+2NC | 0.91 |
| 3RH29112XA040MA0 | 4NC | 0.90 |
Why the top peers are similar
All five share the same front-mount form factor on the 3RH29112 base interface, same SIRIUS series, same box packaging, and the same ROHS3/Active status. The variation between them is purely contact-function count and NO/NC ratio. The 3RH29112XA400MA0 (4NO) and 3RH29112XA310MA0 (3NO+1NC) share the same MPN prefix length and similarity score because their contact counts differ only incrementally from 2NO. The 3RH29112XB220MA0 (2NO+2NC) introduces NC contacts alongside the NO complement, offering a mixed-signal profile not present in the primary.
Additional catalog rows at lower similarity (0.87) include the 1NO+3NC, 1NO+2NC, and lateral-mount variants; the lateral versions (3RH29112DA20, 3RH29112DA02) mount to the side of the device rather than the front face, which changes enclosure layout requirements.
Selection Considerations
- Contact count: The 2NO variant provides two independent normally-open paths. If more auxiliary contacts are needed, the 4NO or mixed-configuration blocks offer higher density on the same mounting interface.
- NO vs. mixed polarity: Blocks without NC contacts (2NO, 4NO) are suited for control circuits that only require asserted (energized) signal paths. Mixed configurations add break (NC) paths useful for fault-indication or inhibit circuits.
- Mounting position: Front-mount blocks occupy the front face and may affect panel depth or cover clearance. Lateral-mount blocks (where required) move to the side but use a different MPN series.
No electrical ratings (current/voltage) appear in the supplied catalog records for this MPN or its alternates.
FAQ
What contact arrangement does the 3RH29112XA200MA0 provide? It provides two normally-open (2NO) auxiliary contacts.
Which contactor and relay series are compatible with this switch block? The block mounts on 3RH coupling relays and 3RT contactors within the SIRIUS series.
Are the lateral-mount auxiliary switch blocks interchangeable with the front-mount versions? No. Lateral-mount blocks (e.g., 3RH29112DA20) use a different mechanical interface and mounting position. They are separate catalog items requiring their own qualification.