The Siemens 3RT1016-1AF01-1AA0 is a SIRIUS S00 power contactor rated 4 kW at 400 V in AC-3 duty — that's the motor-switching rating that governs most industrial loads like pumps, fans, and small conveyors. The AC-1 resistive rating is 10 A at 24 V, which covers heater banks and lighting contactor applications. For the tougher AC-4 reversing or plugging duty, it's rated 8.5 A at 400 V, so factor that in if you're cycling a motor direction frequently. The screw terminals accept 2x (0.5 to 1.5 mm²) solid or 2x (0.75 to 2.5 mm²) stranded, with a max of 2x (0.75 to 4 mm²). That's enough for the main circuit wiring on a 4 kW motor at 400 V.
Coordination and protection — type 1 vs type 2
For Type 1 coordination (contactor may need replacement after a fault), a 35 A gL/gG fuse is specified. If your panel spec requires Type 2 — common on critical process lines — size the upstream fuse at 20 A, not 35 A.