The Siemens 3RT2017-1UB42-1AA0 is a SIRIUS 3RT series power contactor, 3-pole, rated AC-3e/AC-3 at 12 A and 5.5 kW at 400 V. The AC-3e rating covers standard squirrel-cage motor switching — making and breaking running motors — so the 12 A figure is the motor full-load current it can handle, not a resistive-heater rating. The 24 V DC coil includes an integrated varistor for surge suppression, which saves adding an external snubber on the coil circuit. The auxiliary contact block carries 1 NC contact, screw-terminated. Size S00 is the smallest SIRIUS frame, so it fits tight DIN-rail layouts in control panels where space is at a premium. Upright mounting position is specified; if you lay it sideways, derate per the manufacturer's mounting guidelines.
Compliance documentation is available: RoHS compliant since October 2009, and REACH Article 33 data is published for the candidate list.
Cross-reference identifiers
The Siemens group code for this line is R711, and the product group is 5330. These are internal Siemens cataloging fields that sometimes appear on legacy BOMs or in SAP lookups — useful if you are reconciling a spare-parts list that uses those codes instead of the order code.