What this LED-stack module is
The Siemens 3RA9012-5CF57 is a GM-SET / item number 12878 light and alarm LED-stack module kit. It is a green light module with an integrated LED, operating on 24 VDC, and includes both the light module and the LED as a single kit.
Sourced through independent distribution channels.
Where it fits in a panel
This LED-stack module mounts onto a Siemens motor starter or control system signal tower base. The 24 VDC supply means it integrates directly into standard industrial control voltage circuits without an additional transformer. The green LED signals a normal or running condition — common in motor starter applications where the stack indicates motor status (running, stopped, fault) at the panel or machine face.