The Siemens SIRIUS 3RT1016-2MB42-0KT0 is a size S00 power contactor with a 24 VDC coil, rated 10 A at 24 V for AC-12 duty.
The 10 A AC-12 rating at 24 V is the resistive-load switching capacity — that's the figure to match against your control transformer or heater load, not the motor-duty numbers. For motor switching, the contactor is rated 4.5 kW at 500 V and 5.5 kW at 690 V, so it handles standard three-phase induction motors up to about 5.5 kW at 690 V line voltage. The coil holds at 1.4 W DC (closing and holding power are the same), and the mechanical life is 30 million cycles — that's a long service interval for a panel that cycles once per minute. For short-circuit protection, type of coordination 2 requires a gL/gG fuse rated 20 A; type 1 coordination allows a 35 A fuse. That's the spec your panel designer needs to size the upstream protection device.
Integration notes
Side-by-side mounting is allowed (6 mm spacing at the side), so you can pack multiple units in a row without derating. The spring-loaded terminals accept 2x (0.25 to 2.5 mm²) solid or stranded wire (AWG 24 to 14) — strip length is not stated here, but standard practice for spring-cage is 8–10 mm.