What this SIRIUS 3RA2 non-fused motor starter packs
This is a Siemens SIRIUS 3RA2115-4AD18-1AK6 non-fused motor starter — a direct starter in size S00, built as a pre-assembled unit combining a contactor and a thermal bimetallic overload relay. It ships with the 3RT2018-1AK61 contactor and the 3RA1921-1DA00 link module already matched, plus a busbar adapter (8US1251-5DS10) for snapping onto 60 mm busbar systems — no separate component selection needed for the motor branch.
Rated power and trip class — what they mean for motor protection
For longer start times (high-inertia loads like fans or centrifuges), you'd step up to Class 20 or 30. The thermal bimetallic overload release tracks motor heating through an indirect heating element — it's ambient-compensated within the -20 to +60 °C operating range, so seasonal temperature swings in the panel won't cause nuisance trips.
Panel fit — dimensions and mounting
Width is 45 mm (size S00 standard), depth 155.1 mm, height 200 mm — the depth is the dimension to watch when laying out the enclosure depth, especially if the busbar adapter protrudes. Mounts vertically with fastening for snapping onto 60 mm busbar systems — no DIN rail required if you're using the busbar adapter. Clearance needed: 20 mm above, 10 mm below, 9 mm to the side, and zero forward or backward. Degree of pollution 3 means it's rated for conductive pollution environments typical in industrial control panels — no additional conformal coating needed for normal factory-floor conditions.
For volume or blanket orders, the busbar adapter (8US1251-5DS10) and link module (3RA1921-1DA00) are included as supplied components — confirm the BOM line for the contactor (3RT2018-1AK61) is covered by this assembly.