The Siemens SENTRON 3VA9588-0VK10 is a rear interlock mounting bracket accessory, designed for the 3VA15 and 3VA25 1000-frame molded case circuit breakers. It's the mechanical interlock piece that goes on the back of the breaker to prevent two sources from closing in on a common bus — a standard requirement for transfer or dual-feed panels.
What this bracket fits
Mounts to the rear of 3VA15 and 3VA25 breakers in the 1000-frame size. The '1000' in the description refers to the frame rating, not a current number — these are the larger frames in the 3VA family, typically used for main or feeder breakers in distribution panels. You need one bracket per pair of breakers you want to interlock. No wiring involved — it's a purely mechanical accessory. The bracket physically blocks the operating mechanism of one breaker when the other is closed, so it's a positive mechanical interlock, not an electrical one. That matters for code compliance on emergency transfer schemes where you can't rely on electrical interlocks alone.