Motor switching and coil drive
The Siemens 3RT2017-1HA41 is a SIRIUS 3RT series power contactor rated for AC-3e/AC-3 duty at 12 A, switching 5.5 kW at 400 V — the AC-3e rating means it's tested for the higher electrical endurance of modern motor starting profiles, not just the older AC-3 curve. The 12 V DC coil operates across 0.7 to 1.25 times the rated control supply voltage, so it holds in reliably at 8.4 V and picks up cleanly at 15 V DC. That wide tolerance is useful when the control transformer is shared with other loads that sag the bus during simultaneous pick-up.
Frame size and auxiliary configuration
This contactor uses the S00 frame size — the smallest in the SIRIUS 3RT family, sized for panel density where every millimeter counts. It ships with one built-in normally open auxiliary contact on screw terminals. A key constraint: no auxiliary switch block can be added later, so the single NO is all you get. If your circuit demands a second auxiliary pole or a NC break before the main contacts, step up to the S0 frame variant. The screw terminals accept solid or ferruled stranded conductors typical of control panels, and the compact 61.5 x 50 x 77.5 mm footprint fits standard DIN-rail mounting.