SIRIUS S0 power contactor — 27 A at 480 V, screw terminals, snap-on DIN rail
The Siemens SIRIUS 3RT2027-1AP00-1AA0 is a Size S0 power contactor rated 27 A at 480 V in AC-3 duty — the figure that governs motor switching on a 480 V line. It carries 5 hp at 230 V as a motor sizing shorthand. The coil is screw-type terminals; the main and auxiliary contacts share the same terminal style. An auxiliary switch is integrated into the assembly.
Duty-cycle limits and switching rates
Mechanical switching frequency is duty-dependent: 1 000 cycles/h at AC-1 (resistive), 750 cycles/h at AC-2 and AC-3, 250 cycles/h at AC-4. The AC-3e rating matches the AC-3 maximum at 750 cycles/h. Arcing time is 10 to 10 ms — essentially fixed at 10 ms. Pickup and dropout at AC supply is 4 to 16 ms. DC switching capacity is derated per voltage: 10 A at 24 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V, 3 A at 400 V, 0.6 A at 440 V. These are the rated values for the main contacts — use them for the DC load curve, not the AC-3 number.
Wire range and terminal capacity
Solid and stranded conductors both accept 1 to 10 mm². For dual-wire terminations: 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²).