What this overload relay does for a motor circuit
The Siemens 3RB1246-1PM00 is a solid-state overload relay sized for full motor protection in the 1.25 to 6.3 A range, fitting S00 and S0 contactor frames. It's a standalone-install unit — you mount it separate from the contactor, not ganged — with a straight-through main circuit path (no looping the motor leads back through). The trip class is adjustable from 5 to 30, so you can dial in fast or slow overload response depending on the motor start profile. The auxiliary circuit uses screw terminals, and the relay supports manual, automatic, and remote reset modes. It also includes ground-fault signaling as a standard function — not a bolt-on module.
What the trip-class range means on the line
Class 5 trips fast for short-duration starts; Class 30 suits high-inertia loads. The 1.25–6.3 A range covers fractional to small integral-horsepower motors.