54 mm busbar-mount — the fit constraint for this AS-i slice
The 3RK1901-3FA00 is a Siemens AS-Interface support module, 54 mm wide, designed to mount on a busbar with 40 mm or 60 mm centre-line spacing — it does not carry a PE or neutral conductor connection, so it sits upstream of the load feeder modules that handle the protective-earth and neutral terminations.
Sourcing and compliance — what the record shows
The 3RK1901-3FA00 carries no UL, CSA, CE, or marine approval markings in the available spec record — the buyer should confirm the required certification against the site's local code before committing the BOM line. The module is sourced through independent distribution; availability and current pricing are confirmed at RFQ time against the specific order quantity.