What it is and what it does
The Siemens SENTRON 5SQ2370-2YA16 is a 3-pole miniature circuit breaker (MCB) with C-curve tripping characteristic, rated 16 A at 400 V AC. It is built to EN 60898 with a 3 kA breaking capacity, making it suitable for branch-circuit protection in commercial and light-industrial panels where the prospective short-circuit current stays under that threshold.
What the ratings mean for fit
The C-curve means the breaker trips at 5 to 10 times rated current — a common choice for motor circuits, transformers, and lighting banks with moderate inrush. At 16 A it protects a 3-phase load drawing roughly 11 kW at 400 V. The 3 kA breaking capacity is the maximum fault current it can safely interrupt per EN 60898; if your panel's available fault current exceeds that, you need a higher-rated MCB or a current-limiting upstream device. Thermal derating is built in: at 40 °C ambient the continuous rating drops to 15.2 A, at 50 °C to 14.4 A, and at 60 °C to 13.6 A (–). If the breaker lives in a hot enclosure (stacked with other heat sources), size the load to the derated value, not the 30 °C nameplate.
Installation and panel fit
It occupies 3 modular width units on a DIN rail, with a shallow 55 mm installation depth — useful for tight enclosures where the standard 70–76 mm depth of many SENTRON MCBs won't clear the gland plate or door. Pollution degree 3 and overvoltage category III mean it's rated for fixed installations in industrial environments where transient overvoltages are expected. IP20 provides finger-safe terminal protection once the busbar and wiring are in place.