Siemens 3RV2021-4DA10 is a three-pole motor protection switch (MPCB) in the S0 frame designed for DIN-rail mounting to protect three-phase motors from overloads and short circuits. It uses a Class 10 overload release with an adjustable current setting in the 18–25 A range (nominally 25 A) and provides short-circuit protection rated to 325 A, with 6 kV impulse withstand and IP20 front protection. The device employs spring-type terminals and can be augmented with an optional auxiliary contact via a product extension, with standard switching capacity for motor protection across a 220–690 VAC supply (typical installations around 11 kW).
