What this 4-pole contactor does on your line
The Siemens 3RT1326-1BM40 is a SIRIUS power contactor — size S0 frame, 4 NO main contacts, rated for motor loads up to 11 kW at AC-2 400 V. Coil is 220 VAC. The magnet holds at 5.4 W DC both closing and holding, so the control transformer supplying it needs to handle that inrush without droop. Side-by-side mounting is permitted (no derating gap needed), which saves rail space in a crowded panel. Front face is IP20 — safe to touch, but the terminals underneath are IP00, so the contactor must live inside a panel or enclosure.
The S0 frame is 61 mm wide, 85 mm tall, 101 mm deep — fits standard panel layouts. Side-by-side mounting allowed, so you can pack contactors across the rail without spacing.
These values let you size the upstream protection without guesswork.