The Siemens 3RB1025-2RB0 is an electronic overload relay rated 0.1 to 0.4 A, designed for direct contactor mounting in size S0. It provides Class 20 trip protection for motor circuits, with screw terminals and manual-only reset — no auto-reset option, so it locks out after a trip until an operator clears it. That manual-reset choice suits applications where an unexpected restart could be a safety or process risk, like a conveyor or crusher drive.
This relay snaps onto a Siemens S0 contactor (e.g., 3RT20 series) without additional hardware. The manual-reset button and trip-indicator flag are visible on the front face, so a panel walk-through confirms the relay state without opening the enclosure.