The Siemens 3RB1246-1EM40 is a SIRIUS overload relay with an analog output, covering a setting range of 25 to 100 A and a coil supply of 220 to 240 V at 50/60 Hz. It's the part you reach for when a motor protection relay needs to feed a current-proportional signal back to a PLC or drive — the analog output saves an extra transducer on the line.
The 25 to 100 A setting range covers most medium-frame induction motors (roughly 11 to 45 kW at 400 V). The 220 to 240 V 50/60 Hz supply is the control voltage for the relay's own electronics — not the motor voltage. If your panel runs 24 VDC control, this relay needs a separate control transformer; it won't run off a 24 VDC power supply. The analog output is the key differentiator here versus a standard bimetallic overload. It gives a continuous 4-20 mA or 0-10 V signal proportional to motor current, so a PLC or drive can trend load, detect a jam before the thermal trip, or log runtime data. No separate current transformer needed.
It's sized for the SIRIUS 3RT2 contactor range — the 3RB12 family shares the same footprint. The analog output routes back to a PLC analog input card, typically 4-20 mA, for remote current monitoring.