SIRIUS non-fused direct starter — size S0, factory-matched sub-assemblies
The 3RA2125-4AA26-0AK6 is a Siemens SIRIUS non-fused motor starter, designed as a direct starter in size S0. It ships as a factory-matched assembly that includes the 3RT2026-1AK60 contactor and the 3RA2921-1AA00 link module — no separate ordering or matching of components is required for the basic starter function. The overload release is thermal bimetallic (Trip Class 10), which means it protects the motor against sustained overcurrent while allowing the inrush during a standard start — a Class 10 trip curve is the common choice for general-purpose induction motors driving pumps, fans, and conveyors where the start time stays under 10 seconds.
Mounting and panel integration — DIN rail snap-on with clearance envelope
The starter fastens by snap-on mounting to a DIN rail or, alternatively, by screw mounting with an additional push-in lug. The mounting position is vertical, which is the standard orientation for heat dissipation from the thermal overload. The enclosure footprint is 45 mm wide by 193.1 mm high by 97.1 mm deep. For airflow and wiring access, the required clearances are: 30 mm upward, 10 mm forward, 10 mm downward, 9 mm at the side, and 0 mm backward — the back face sits flush against the mounting surface. The degree of pollution is rated 3, which per IEC 60947-1 means the device is suitable for environments with conductive or dry non-conductive pollution — typical for control panels in industrial settings where dust and occasional condensation are present.
Environmental range and lifecycle status
These limits cover most indoor panel environments and unheated warehouses; the -20 °C lower operating bound is relevant for outdoor enclosures in cold climates.