The Siemens 3RT1026-3XF40-0LA2 is a SIRIUS power contactor in the S0 frame size, designed for switching motor loads in control panels. It carries a 110 VDC coil with an integrated varistor surge suppressor, and is rated for AC-4 duty at 15.5 A at 400 V — the figure that governs reversing or plug-stop applications where the contactor makes and breaks stalled-rotor current.
Mounting and panel integration
Snap-on mounting onto 35 mm DIN rail per EN 50022, with screw terminals for the main circuit. The 45 mm width and 119 mm height fit standard S0 contactor footprints; side-by-side mounting is permitted, so multiple contactors pack tightly on the rail without derating for heat buildup.
Switching capacity and coil
The 110 VDC coil pulls in at 70 % of rated voltage (77 V) and drops out below that threshold. Switching capacity varies by voltage: at 110 VDC it handles 1 A, at 220 VDC 0.3 A, and at 24 VDC 10 A — the DC load curve drops sharply with voltage, so verify the load's make/break current against the table. For AC motor duty, the AC-4 rating at 400 V is 15.5 A, which covers reversing or inching applications on motors up to roughly 7.5 kW.