What it is and what the ratings mean
The Siemens 3RB1035-2UB0 is an electronic overload relay in the SIRIUS 3RB10 family, sized S2 for direct contactor mounting. It covers a 13...50 A adjustment range with Class 20 trip curve — meaning it allows a 20-second thermal memory before tripping on a locked-rotor condition, which is the standard protection band for standard-duty induction motors driving pumps, fans, and conveyors. The screw terminals and manual-only reset (no auto-reset option) suit it for applications where a manual intervention after a fault is preferred — typical in unattended or remote panels where you want a positive reset action before restarting the line.