The Siemens 3RT2316-1BA40 is a SIRIUS contactor in size S00, rated for 4 kW at 400 V in AC-3 duty — that's the motor-switching curve for a standard 4-pole induction motor up to that load. The 12 V DC coil pulls in cleanly on a 24 V DC bus with a dropping resistor or a dedicated 12 V supply; verify the coil suppression diode polarity if the panel uses free-wheel diodes on the PLC output card. The contactor carries an integrated auxiliary switch, so you get one N.O. or N.C. feedback pair without bolting on a separate block.
Side-by-side mounting is allowed — no derating gap needed for the magnetic field. Main circuit terminals accept solid or stranded wire: 2×(0.5…1.5 mm²), 2×(0.75…2.5 mm²), or 2×4 mm². Stranded alone goes up to 4 mm².
Electrical and environmental
Coil voltage is 12 V DC; the pick-up dropout threshold is 0.8 × rated (9.6 V), and the full-scale overvoltage limit is 1.1 × rated (13.2 V). Relative humidity minimum is 10 %. The main circuit impulse withstand voltage is 6 kV; the auxiliary circuit shares the same 6 kV rating. DC operating time is 7 to 13 ms. The contactor is rated for 30 million mechanical operations typical.