The Siemens SENTRON 3VA9504-0JB32 is a sliding bar interlock accessory — a mechanical interlock that prevents two breakers from closing simultaneously, used in transfer-switch or dual-feed applications where you need to guarantee only one source is live at a time. It's part of the 3VA15/25 1000 family, and the TA3.2 terminal block handles stranded copper from 4/0 to 400 kcmil, which covers the heavy feeder cable range you'd typically run into a 1000 A frame. That 225 A rating on the terminal tells you the conductor path itself is sized for the full breaker current — no bottleneck at the lug.
This interlock mounts directly to the 3VA15/25 breaker frame — it's a mechanical add-on, not a standalone device. The TA3.2 terminal accepts both copper and aluminum stranded conductors in the same 4/0 to 400 kcmil range (–), which is useful if your site uses aluminum feeder. Stripped length is 1.02 inches, so prep your cables to that dimension for a proper bite under the lug. No control wire tap on this terminal — it's a straight power connection.
The sliding bar design is a mechanical interlock — it physically blocks the other breaker's handle from moving to ON when one is closed. No wiring, no auxiliary contacts, no logic. It's a field-installable kit, four units per order, so you get enough for a pair of breakers in a typical ATS configuration.