The Siemens SENTRON 5TT5031-2 is an Insta contactor — a panel-mount switching device sized for DIN-rail enclosures. It carries 3 normally-open and 1 normally-closed contact, rated for 400 V at 25 A, with a control coil that accepts AC or 24 V DC.
The Ratings That Drive Fit
Rated 400 V maximum and 25 A, the 5TT5031-2 handles single-phase or three-phase loads up to that current at line voltage. The 24 V AC/DC control coil means you can drive it from a standard 24 VDC power supply or an AC control transformer — no separate coil voltage variant needed. Power loss runs 2.2 W per pole in hot operating state, so the heat adds up in a multi-contactor enclosure; the datasheet calls for spacers between units to keep dissipation under control.
Width is 35 mm (2 modular width units on a standard DIN rail), depth 71 mm, height 90 mm. That 35 mm footprint is what you care about when laying out a crowded enclosure — it's two 17.5 mm slots. The IP20 finger-safe housing is fine for dry indoor panels. The design accepts supplementary add-on devices (auxiliary contact blocks, etc.) which snap on without extra wiring.