The Siemens 3RT7016-1AN21 is a Size S00 contactor from the SIRIUS family — three main poles, normally open, screw-type terminals on both the main and control circuits. It snaps onto a 35 mm DIN rail per DIN EN 50022 and can be mounted in any orientation within ±180° rotation and ±22.5° tilt on a vertical surface, which is handy when you're squeezing it into a crowded panel.
In AC-1 duty (resistive loads like heaters) it's rated 6 A at 230 V and 3 A at 400 V. The AC-3 switching rate tops out at 750 operations per hour, while AC-4 (inching/plugging) is limited to 250 per hour — that's the mechanical wear limit for the contacts under high inrush. Fuse coordination: for type 2 coordination (no damage to the contactor under short circuit) the required upstream fuse is a 20 A gL/gG NH 3NA; for type 1 (contactor may need replacement) it's 35 A. That tells you the short-circuit withstand capability.
Coil and control side
The DC coil draws 0.8 W on pickup and holds at 0.27 W. Auxiliary switch blocks can be added on the front (product extension auxiliary switch is supported), and the contactor can be mounted side-by-side without derating in still air.