The Siemens 3RB1262-0LG21 is a solid-state overload relay from the SIRUS 3RB12 series, rated for motor protection from 200 to 820 A on AC supplies at 110 to 120 V, 50/60 Hz. It integrates thermistor motor protection and internal earth-fault detection, with separate bistable output contacts: 1NO/1NC for overload/thermistor and 1NO/1NC for earth fault. The 200 to 820 A range covers large-frame motors, compressors, and pumps in industrial panels. The solid-state design eliminates mechanical wear on the overload trip curve, and the integrated earth-fault detection saves a separate monitoring relay in the cabinet.
Deployment Context
Mounts on a DIN rail in the motor control center or panel enclosure. The 110 to 120 V control supply is typical for North American panels; the 50/60 Hz rating means it works on either line frequency without derating. The bistable outputs latch their state after a trip, so the relay remembers an overload or earth-fault condition even if control power is cycled — useful for remote fault indication without a separate memory circuit.