Siemens 6GK5991-1AF00-8GA0 SCALANCE X SFP991-1LD A 100 Mbit/s LC Single-Mode 26 km SFP Transceiver Module

The Siemens 6GK5991-1AF00-8GA0 (SFP991-1LD A) is an active plug-in SFP transceiver for the SCALANCE X media module slot, adding one 100 Mbit/s optical LC port. It runs single-mode fiber and covers a range of up to 26 km at 1310 nm on the 100BASE-LX link. Operating temperature extends to -40...+95 degrees C, and IP20 latched mounting keeps installation straightforward inside the switch housing.

Technical Specifications

Certifications & Standards

• CE
• C-Tick
• EPD

Selection Notes

The A suffix on the SFP991-1LD A marks Siemens' extended-temperature build: -40 to +95 degrees C operation, with a 16-hour rating at the top end, versus the -40 to +85 degrees C spec on the standard SCALANCE X media modules, making it the choice for switches in unheated cabinets or direct sun exposure. Its single-mode link reaches up to 26 km, far beyond the 5 km limit of the multimode ST/BFOC media module in this series, so it is the transceiver to specify whenever the fiber run between two SCALANCE X switches exceeds multimode distance limits. Pick a standard-temperature single-mode SFP instead when the installation stays inside a climate-controlled cabinet, since the optical budget is the same at a lower net weight.