What the integrated protection functions mean for your motor circuit
The 3RB1246-1PG00-0FM0: This relay combines three monitoring functions in one DIN-rail-mount housing: thermal overload protection via a solid-state sensing circuit, thermistor (PTC) motor protection for embedded winding-temperature monitoring, and ground-fault detection through the connection of an external summation current transformer. The ground-fault monitoring is a separate channel with its own 1 NO / 1 NC output, independent of the overcurrent/thermistor channel which also provides 1 NO / 1 NC contacts. All contacts are monostable, meaning they return to their de-energized state on loss of control power — a safety-relevant feature that ensures a fault condition is not masked by a power failure.
The 1.25...6.3 A setting range covers small to medium motor loads — typical for pumps, fans, or conveyors up to roughly 3 kW at 400 V. The solid-state design eliminates the mechanical wear and ambient-temperature drift of a bimetal overload, making it suited for applications requiring repeatable trip performance or frequent starting cycles. Ground-fault monitoring requires an external summation CT (not included); the relay provides the trip logic and output contacts.