The Siemens SIRIUS 3RT1035-1AH20-1AA0 is a size S2 power contactor with a 48 V 50/60 Hz coil. That 55 mm width and 112 mm height mean it fits standard enclosure backplanes without crowding adjacent devices. The 115 mm depth is the dimension to watch when you're laying out gland plates or door clearance — it's not a shallow unit, so plan for that reach into the enclosure. Rated for 22 kW at 500 V and 11.4 kW at 690 V, this contactor handles the motor branch circuit for pumps, fans, and conveyors in that power band.
The coil pulls 48 V at either 50 or 60 Hz, with an operating range of 0.8 to 1.1 times rated voltage at 50 Hz and 0.85 to 1.1 at 60 Hz. That means the coil holds in reliably down to about 38.4 V on a 50 Hz supply — useful if your control transformer is lightly loaded or you've got long cable runs. That's enough cross-section for the full rated motor current without needing lug adapters. The auxiliary contacts are rated 10 A at 24 V, derating to 0.3 A at 220 V — enough for PLC inputs or pilot lights on the same control voltage. The IP20 front keeps fingers out; the IP00 terminal area expects enclosure protection. Mechanical life is typical 10 million operations, and the switching frequency tops out at 1 200 cycles per hour for AC-1 resistive loads, 1 000 for AC-3 motor starting. That's a solid 3-second cycle time at maximum — fine for rapid cycling applications like indexing conveyors.
That's fast enough for most motor control schemes but not so fast that you'll get nuisance dropouts from voltage sags. The coil suppression is built into the design — no external flyback diode needed for the AC coil.