The Siemens 3RB1262-0LG10 is a SIRIUS overload relay rated 200-820 A for full motor protection, fitting the S10/S12 frame sizes. It's designed for continuous or individual mounting with busbar connection on the main circuit and screw terminals on the auxiliary circuit. The relay offers adjustable trip class from 5 to 30, manual-automatic-remote reset, monostable outputs, and an overload warning function on AC 110-120 V, 50/60 Hz control supply.
Busbar connection on the main circuit means no lug crimping for the power path — the relay clamps onto the busbar system, which saves panel space and reduces wiring errors at high current. The auxiliary circuit uses screw terminals, so a standard slotted or Pozidriv driver is all you need for the control wiring. The AC 110-120 V control coil draws its supply from the same control transformer feeding the contactor; verify the control transformer VA rating covers both the contactor holding current and this relay's control circuit draw.
The 200-820 A range covers large motor loads — think 250-600 hp at 480 V, depending on motor full-load current. The adjustable trip class (5-30) lets you match the relay's thermal curve to the motor start profile: Class 5 for fast starts with low inertia loads like centrifugal pumps, Class 10 for general-purpose, Class 20 for high-inertia loads like fans or crushers, and Class 30 for extremely long acceleration times. The overload warning output (monostable) can trigger a PLC alarm before the trip threshold is reached, giving the operator a heads-up on an impending overload condition.