The Siemens 3RV2021-0AA10-0DA0 is a SIRIUS 3RV2 motor starter protector in the size S0 frame. The A-release is set for 0.11 to 0.16 A with a fixed short-circuit release of 2.1 A. Screw terminals, standard switching capacity. This is the overcurrent and short-circuit protection piece for a motor branch circuit — sits upstream of the contactor in a standard IEC starter combo.
The S0 frame is the most common size in the 3RV2 line — fits the same footprint as the contactor it pairs with. Screw terminals accept standard ferruled or solid copper up to the rated cross-section. Packaged singly; dimensions 102 x 57 x 104 mm.