The Siemens 3RB1262-0LM00-0FM0 is a solid-state overload relay rated for 205-820 A AC at 220-240 V, 50/60 Hz. It integrates thermistor motor protection (compatible with Kloeckner-Moeller ZWA820 thermistors) and ground-fault monitoring via an external summation current transformer. The relay provides two sets of contacts: 1 NO + 1 NC for overload/thermistor alarm, and 1 NO + 1 NC for ground-fault alarm, both monostable.
The 205-820 A range covers large motor loads — think 150-600 kW induction motors at 400 V. The 220-240 V control supply is the relay's own operating voltage, not the motor voltage; it powers the internal electronics and the trip logic. The ground-fault monitoring requires an external summation current transformer (not included), so factor that into the BOM. The monostable contact action means the relay resets automatically when the fault clears — no manual reset needed, which suits remote or unmanned installations.
This relay goes into motor control centers (MCCs) and large control panels protecting pumps, compressors, conveyors, and fans. The solid-state design handles frequent starts and harsh environments better than a bimetallic overload. The integrated thermistor input lets it protect motors with PTC thermistor windings directly, without a separate thermistor relay module.