Part identity and core ratings
The Siemens SIRIUS 3RT2016-2KB42 is a coupling contactor in size S00, designed for switching loads in control panels where galvanic isolation or signal-level switching is required — not a power motor starter, but a relay-grade interface between a controller and a higher-current circuit. The coil pulls in at 24 VDC nominal, and the main contacts are rated for 10 A at that same 24 V, which tells you this part lives on the control-voltage side of the panel, not the load side. Provided the contactor is mounted on a 35 mm DIN rail per DIN EN 60715, with the specified clearances — 10 mm upwards and forwards, 6 mm at the sides — the thermal path holds the unit on the grid through the rated operating range of -25 to +60 °C.
Termination and wiring
The magnet coil terminates via spring-type terminals, which accept solid or stranded conductors from 0.5 to 4 mm², and up to 2x (0.5 to 4 mm²) when doubling up. That spring-cage design eliminates the need for a screwdriver torque check during commissioning — push the ferrule in, it holds. The main contact wiring range follows the same cross-section, so a single wire gauge serves the whole contactor. Strip length is not listed here, but the standard for Siemens spring terminals on this frame is 10 mm; verify against the unit in hand before terminating.
Mounting and clearances
Mounting is screw or snap-on onto 35 mm DIN rail per DIN EN 60715. The mounting position allows +/-180° rotation on a vertical surface, and can be tilted forward or backward by +/-22.5° — useful when the contactor sits on a swing-frame panel or a gland plate that isn't perfectly plumb. Clearance requirements: 10 mm upwards, 10 mm forwards, 6 mm at the sides, and 10 mm downwards. The depth is 73 mm, width 45 mm, height 70 mm — this is a compact S00 frame, so it leaves room for adjacent devices on the same DIN rail, provided you respect those side gaps for heat dissipation.
Switching performance and endurance
Mechanical endurance is rated at 30,000,000 operations typical — that is the contactor's structural life before wear-out, not the electrical life under load. Electrical switching frequency depends on the duty category: at AC-1 (resistive loads) the maximum is 1,000 operations per hour; at AC-2 and AC-3 (motor starting, slip-ring motors) it drops to 750 ops/h; at AC-4 (plugging, inching) it is 250 ops/h. The arcing time is 10 to 15 ms, and the DC switching time (operate + release) is 7 to 20 ms. For a coupling contactor that sees frequent signal-level switching, the mechanical life is generous; the electrical life at 24 VDC and 10 A will be the limiting factor — derate if switching inductive loads like small solenoids.