SIRIUS S0 power contactor — 24 VDC coil, screw terminals, DIN-rail mount
The Siemens 3RT2026-1BB40-ZW96 is a SIRIUS S0 power contactor with a 24 VDC coil and screw-type terminals, designed for switching motor loads and resistive circuits in industrial control panels. It snaps onto a 35 mm DIN rail per DIN EN 60715 and occupies a 45 mm width, fitting standard enclosure layouts. The coil draws 10 A at 24 V rated value, with a pick-up threshold of 0.8 x rated voltage and a drop-out of 1.1 x full-scale value — meaning the contactor holds in reliably down to about 19.2 V and releases cleanly above 26.4 V. Switching times are 15 to 17.5 ms DC for the main contacts, with an arcing time of 10 ms.
Duty-cycle and switching frequency
Maximum switching frequency depends on the load duty: 1 000 operations per hour for AC-1 (resistive), 750/h for AC-2 and AC-3 (motor starting/running), and 250/h for AC-4 (plugging/inching). The AC-3e rating also allows 750/h. These limits govern thermal rise in the coil and contacts — exceeding them shortens life or causes nuisance tripping. Mechanical life is typical 10 million operations, so the contactor outlasts most panel cycles when operated within the rated electrical duty.
Mounting and wiring
Mounting position is flexible: the contactor can be rotated ±180° on a vertical surface and tilted forward/backward ±22.5°. Minimum clearances are 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the side — important for heat dissipation and arc flash clearance in dense panels. Main circuit terminals accept solid or stranded wire from 1 to 10 mm², with auxiliary contacts accepting 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) solid or stranded. The screw-type terminals are standard for panel wiring.