The Siemens 3RA2115-0HD15-1AP6 is a SIRIUS non-fused motor starter in size S00, configured as a direct starter with a thermal bimetallic overload relay and a magnetic short-circuit trip. It ships as a factory-assembled unit including the 3RT2015-1AP61 contactor, the 3RV2011-0HA15 circuit-breaker, the 3RA1921-1DA00 link module, and the 8US1251-5DS10 busbar adapter — one order code, one assembly, ready to snap onto a 60 mm busbar system.
The Trip Class 10 means the bimetallic overload relay will trip within 10 seconds at 7.2× the thermal setting, which is the standard for standard-duty induction motors (pumps, fans, compressors) that don't need the slower Class 20 or faster Class 5. The 45 mm width and 200 mm height fit the S00 footprint — the smallest Siemens load feeder size, which is the one you reach for when panel space is tight but you still need a full motor branch (contactor + overload + breaker) in one package. The 155.1 mm depth includes the busbar adapter; the 20 mm upward clearance and 10 mm downward clearance are the minimum free air space around the enclosure for heat dissipation from the bimetallic element.
Mounts vertically by snapping onto a 60 mm busbar system — no DIN rail required, no additional adapter. The supplied 8US1251-5DS10 busbar adapter is already included, so you don't order it separately. Main contacts accept stranded conductors from 0.5 to 4 mm² (single) or 2× (0.75 to 2.5 mm²) for paralleled feeds; AWG equivalents are 2× (20–16) for the contactor side and 2× (18–14) or 2× 12. The auxiliary switch extension is available as a product extension option if you need additional signaling contacts beyond what the base unit provides.