What it is and where it fits
The Siemens 3RV2011-1BA15-ZW96 is a SIRIUS motor protection circuit breaker — the thing that sits between your contactor and the motor, combining overload and short-circuit protection in one 45 mm wide package. Screw it onto a 35 mm DIN rail per DIN EN 60715, and you've got a coordinated protection device for a three-phase motor branch. Trip Class 10 means it will trip within 10 seconds at 7.2× the thermal setting — standard for general-purpose motor starting where the inrush doesn't drag out. Phase failure detection is built in, so a single-phased motor won't cook itself waiting for the overload curve. The interrupting ratings are serious: 100 kA at 240 V and 400 V, dropping to 10 kA at 690 V. That 100 kA at 400 V means it can sit downstream of a transformer with high fault current without needing a separate current-limiting fuse — saves a fuse holder and a wiring step.
Mounting and spacing
Width is 45 mm — three TE on a DIN rail. Depth 97 mm, height 97 mm. Clearance requirements: 50 mm above and below, 30 mm to the side, zero forward or backward. That's tight enough for a crowded panel but leaves room for cable bending below the terminals. Mounting position is any orientation, which helps when you're squeezing it into a sub-panel or a machine-mounted enclosure. Screw and snap-on onto 35 mm rail — the screw terminals are M3 for the main contacts, accepting 2× (0.5 to 2.5 mm²) solid or stranded.