What it is and what it does
The Siemens 3RT1016-2KB42 is a SIRIUS power contactor in frame size S00, designed for switching motor loads and resistive loads in industrial control panels. It mounts on a 35 mm DIN rail per EN 50022, with a 45 mm width that fits standard panel layouts. The coil is rated 24 VDC, with a holding power of 2.3 W and closing power of 2.3 W — a DC coil means no AC hum and lower inrush compared to an equivalent AC coil, but verify your control transformer can supply the DC bus cleanly. Main power terminals are spring-loaded, accepting 2x (0.25 to 2.5 mm²) solid or stranded wire, or 2x (24 to 14 AWG). Spring-cage termination speeds up panel wiring and holds better under vibration than screw terminals, but requires the correct ferrule or stripped length.
Key ratings and what they mean for fit
Rated operational current at AC-12 (resistive load) is 10 A maximum. For motor duty, the AC-3 rating at 400 V is 4.5 kW, and at 690 V it is 5.5 kW — these are the numbers that govern real motor switching, not the resistive maximum. The contactor carries an AC-4 rating of 8.5 A at 400 V, which covers reversing or inching duty where the contactor makes and breaks the motor at full current. If your application cycles the contactor under load, this is the rating to size against. The built-in varistor surge suppressor clamps coil voltage spikes on the DC coil. This is standard for SIRIUS contactors and means you do not need an external suppression diode across the coil — but verify polarity: the varistor is polarity-sensitive. Operating temperature range is -25 to +60 °C, with degree of pollution 3 (conductive pollution or dry non-conductive pollution that becomes conductive due to condensation). This suits most industrial enclosures but not clean-room or sealed environments without derating. Front-side protection is IP20 — finger-safe but not sealed. Side-by-side mounting is permitted with a 6 mm gap at the side for heat dissipation. No forced derating for side-by-side mounting is stated, but in a densely packed panel, check the thermal rise.
Where it is used
This class of SIRIUS power contactor is used in motor control centers, conveyor systems, pump panels, and HVAC control for switching three-phase induction motors up to 5.5 kW at 690 V. The S00 frame is the smallest in the SIRIUS family, suited for compact sub-distribution boards and machine control cabinets.