What this part is and what it does
The Siemens 3RB1246-1QG20 is an overload relay for full motor protection, sized for S00/S0 contactor frames. It covers a 6.3...25 A setting range with adjustable trip Class 5...30, so you can match the thermal curve to the motor's starting profile — fast for pumps, slower for high-inertia loads. This is a standalone-installation unit with straight-through main circuit wiring and screw terminals on the auxiliary circuit. It offers manual, automatic, and remote reset options, plus integrated ground fault detection with monostable outputs for ground fault signaling at AC 110...120 V, 50/60 Hz.
What the ratings mean for fit
The 6.3...25 A setting range determines which motor FLA this relay can protect. The adjustable Class 5...30 lets you dial in the trip delay: Class 5 for fast protection on short-start motors, Class 30 for high-inertia loads like fans or centrifuges that take longer to reach speed. Integrated ground fault detection with monostable outputs means the relay can signal a ground fault condition separately from an overload — useful for systems where ground faults need distinct alarming or a different response than a standard trip.
Where it goes in the panel
This relay mounts on a DIN rail in the control panel, sized for S00/S0 contactor frames. The straight-through main circuit wiring simplifies bus-bar or cable routing, and the screw terminals on the aux circuit are standard for panel builders — no special tooling needed.