The Siemens 3RA2316-8XB34-1DB4 is a SIRIUS reversing contactor assembly — a pre-wired pair of contactors with mechanical and electrical interlock, so that only one direction can be energized at a time. It ships with two 3RT2016-1DB44 contactors already installed, each rated 4 kW at 400 V in AC-3 duty (cites:) and 4 kW at 400 V in AC-4 reversing duty (cites:). The coil is 24 VDC and includes a built-in varistor surge suppressor (cites:) to clip the inductive kickback on dropout — a detail that saves you an external suppression module and keeps noise off the DC supply.
Clearance around the unit: 6 mm upwards, forwards, downwards, and to the side; zero clearance needed backwards (cites:,). Overall dimensions are 90 mm wide x 68 mm high x 145 mm deep (cites:,).
Terminal wiring
Both the main current circuit and the magnet coil use screw-type terminals (cites:,). The power terminals accept: 2x (0.5... 1.5 mm²), 2x (0.75... 2.5 mm²), or 2x 4 mm² solid or stranded (cites:,). That covers the common motor-lead sizes for a 4 kW load at 400 V — no special ferrules or bootlace crimps required, though stranded wire benefits from them for a consistent clamp.