SIRIUS S00 power contactor — 24V DC coil, spring-terminals, varistor
The Siemens 3RT1016-2KB42-ZX95 is a SIRIUS size S00 power contactor with a 24V DC magnet coil, built-in varistor surge suppression, and spring-loaded terminals on the main circuit. It's rated for motor switching up to 5.5 kW at 690 V AC (AC-3 duty), meaning it handles standard three-phase induction motors up to that power class. The 24V DC coil draws 2.3 W both on pickup and hold — a constant-power coil design that simplifies DC supply sizing in the panel. Snap it onto 35 mm DIN rail per EN 50022, or screw-mount. Side-by-side mounting is allowed with zero gap — the 6 mm side clearance spec is for air circulation, not mandatory spacing. At 45 mm wide, it fits standard 45 mm slot in a modular enclosure row.
Ratings and what they mean for your load
AC-3 motor switching: 4.5 kW at 500 V, 5.5 kW at 690 V. That's the rating that governs real motor loads — pumps, fans, compressors. AC-4 at 400 V is 8.5 A, for reversing or inching duty where the contactor makes and breaks stalled-rotor current. The AC-2 rating at 400 V is 4 kW, covering slip-ring motor starting. For resistive or lightly inductive loads (AC-1), the maximum operating current is 10 A at 400 V. The auxiliary contact ratings cover control circuits: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, 0.3 A at 220 V DC — enough for most PLC output or relay interface signals. Mechanical endurance is 30 million operating cycles typical — a high figure for an S00 frame, suited for frequent cycling applications like conveyor diverters or packaging machinery. Pollution degree 3 means it's rated for industrial environments with conductive contamination; the IP20 front and terminal protection keep fingers out but the contactor needs to live inside a cabinet.
Coordination and protection
For type 1 coordination (no damage to the contactor after a short-circuit, but may need replacement), the required upstream fuse is 35 A gL/gG. For type 2 coordination (contactor remains usable after a fault), use a 20 A gL/gG fuse. The varistor across the coil suppresses switching transients — no external RC snubber needed for the DC coil. Ambient operating range is -25 to +60 °C, with no derating stated below 2000 m altitude. The spring-loaded terminals accept 2x 0.25 to 2.5 mm² solid or stranded, or 2x 24 to 14 AWG — standard for panel wiring. Strip length and ferrule use follow the manufacturer's termination guide; the spring clamp holds firm under vibration common in machine-mounted enclosures.