Siemens 3RT2026-2DB40 SIRIUS Power Contactor — 24 VDC, Size S0, Spring-Terminal
It uses a 24 VDC coil and spring-type terminals for tool-free wiring. Rated operational current for the main contacts is 18 A (AC-3 duty at 400 V), which means it can handle a 7.5 kW motor at 400 V three-phase — the typical rating for a small conveyor, pump, or fan drive.
The 24 VDC coil draws 6 A at rated voltage — a significant inrush for a control transformer; size the DC supply for at least 150% of this to handle the pick-up surge. Coil operate time is 15 to 17.5 ms DC, arcing time 10 ms, so the contactor makes and breaks fast enough for most motor-starting sequences. Switching frequency limits vary by duty: up to 1000 operations per hour for resistive loads (AC-1), 750/h for motor starting (AC-3 and AC-3e), and 250/h for plugging or inching (AC-4). For high-cycle applications like a stamping press or rapid indexing conveyor, stay within the AC-4 limit to avoid contact welding. Spring-type terminals accept solid or stranded wire from 1 to 10 mm², or two conductors of 0.5 to 2.5 mm² each. No screwdriver needed for termination — just push and lock, which speeds up panel wiring and reduces torque errors. This matters when packing contactors side-by-side in a high-density panel — you need that 6 mm gap for arc flash isolation.