Siemens 3RT2027-1AB00 SIRIUS S0 Power Contactor
The Siemens 3RT2027-1AB00 is a SIRIUS S0-frame power contactor rated for motor switching at 27 A in AC-3 duty at 480 V, making it a direct fit for controlling three-phase induction motors up to that load current in a 480 V distribution. It carries a 1 NO + 1 NC auxiliary contact block built in, screw-type coil terminals, and mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715 — standard panel integration for a 45 mm wide device.
The AC-3 rating of 27 A at 480 V is the key figure for motor starting — it governs the contactor's ability to handle inrush and break running current for squirrel-cage motors. For resistive loads (AC-1), the maximum switching frequency is 1,000 cycles per hour; for AC-3 motor duty it's 750 cycles per hour, and for the more severe AC-4 plugging/reversing duty it drops to 250 cycles per hour. The DC switching capacity is specified across multiple voltages: 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, and 3 A at 400 V — useful for DC brake or control circuits fed from the same contactor. Mechanical endurance is listed at 10 million operating cycles typical, and the contactor operates in ambient temperatures from -25 °C to +60 °C, with storage from -55 °C to +80 °C.
The S0 frame measures 85 mm high, 45 mm wide, and 97 mm deep. Clearance distances are specified: 10 mm upwards, downwards, and forwards; 6 mm at the sides. Main circuit terminals accept solid or stranded conductors from 1 to 10 mm², with fine-stranded (ferruled) capacity of 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²).