The Siemens 3RB1246-1EM31 is a solid-state overload relay that covers the 25 to 100 A motor protection range on a 220 to 240 V AC supply, 50/60 Hz. It integrates thermistor motor protection and internal earth-fault detection into a single device, with bistable output contacts: 1NO/1NC for overload, thermistor, or earth-fault, plus a separate 1NO/1NC for overload warning. The current lifecycle stage is active, so it remains a current-production line item for new panel builds and BOM replacements.
The 25 to 100 A current range is the adjustable overload trip band for a motor branch circuit — it directly determines which motor FLA this relay can protect. The 220 to 240 V AC control supply powers the internal electronics; the relay won't energize if that voltage is outside the specified range. Integrated thermistor protection means the relay accepts a PTC thermistor chain from the motor windings and trips on overtemperature, covering a failure mode that a standard bimetallic overload cannot. The internal earth-fault detection monitors for leakage to ground, adding a layer of protection that normally requires a separate module. Bistable outputs latch their state after a trip — they don't drop out when control power is lost, so the trip condition is preserved for diagnostics even in a power-down scenario.