What it is and what it does
The Siemens SENTRON 5TT5733-2 is an insta contactor — a compact, DIN-rail-mount switching device designed for lighting and resistive loads in commercial and industrial panels. It carries 4 normally-closed (NC) contacts and zero normally-open (NO) contacts, so its job is to break a circuit when the coil is energized and close it when the coil drops out. That makes it a natural fit for fail-safe or emergency-off circuits where the load must be disconnected on loss of control power. Rated operating current is 24 A at AC, and the coil pulls in on 24 V AC/DC. The main contacts are rated for 230 V nominal with a maximum of 440 V. That 24 A rating at 230 V handles a 5.5 kW resistive load comfortably; the 440 V ceiling means it can also switch 400 V line-to-line circuits in a three-phase panel, though the 24 A rating applies at the rated voltage — derate for higher voltages per the thermal curve.
Where it fits in the panel
The 5TT5733-2 occupies 2 width units (36 mm) on a 35 mm DIN rail per DIN EN 50022. Body dimensions are 71 mm deep, 36 mm wide, 90 mm tall, with an installation depth of 64 mm. That shallow install depth leaves room behind the DIN rail for wiring troughs or busbars — a detail that matters when you're packing contactors into a crowded enclosure. IP20 protection means it's safe from finger contact but not from moisture or dust ingress — keep it inside a sealed enclosure in washdown or outdoor locations. The function code Q per DIN EN 61346-2 and DIN EN 81346-2 tells the panel designer this device is a switching function, not a protection or control element, which helps with consistent terminal marking across the build.