The Siemens SIRIUS 3SE7120-2DD01 is a cable-operated switch in a painted metal enclosure with a grey plastic cover, rated IP65. It carries one normally-closed and one normally-open safety-related switching contact, with silver contact material. The thermal current is rated at 6 A, and the insulation voltage at 400 V. Surge voltage resistance is 6 kV, and the ambient temperature range during operation is -25 to +70 °C.
The 6 A thermal current (Ith) is the continuous current the contacts can carry in free air — this is not the motor-breaking rating. The switching capacity depends on voltage: at 240 V AC it is rated 6 A, at 400 V AC also 6 A, but at 250 V DC it drops to 0.27 A. For a 24 V DC control circuit, the rated value is 3 A. The cable entry is a single M20 x 1.5 gland; the screw-type terminals accept 2x 0.5 to 2.5 mm² solid or 2x 20 to 14 AWG stranded wire.
Mounts via screw fixing — no DIN rail. The enclosure measures 172 mm high, 53 mm wide, 43 mm deep. Cable entry is a single M20 x 1.5 threaded hole. The circuit principle is a jump function (changeover contact). No status display or emergency stop function is built in.