Siemens 3RB1253-0FB00 Overload Relay, 50-205 A, Discontinued

The 3RB1253-0FB00: The 50-205 A current range covers medium to large motor loads — think pumps, compressors, or conveyors in the 25-100 kW ballpark depending on voltage. The adjustable trip class (5-30 F) lets you match the relay's thermal curve to the motor's starting profile: a lower class for quick-starting fans, a higher class for high-inertia loads like centrifuges. Ground fault signaling at DC 24 V integrates into a standard safety circuit, so a ground leak trips the relay and flags the fault on a PLC input without extra hardware.