The Siemens 6EP1331-2BA10 is a SITOP PSU100M series regulated switch-mode power supply that takes a 120-230 V AC line input and delivers a safety extra-low voltage (SELV) 24 V DC output rated at 0.5 A continuous. It snaps onto a standard DIN rail EN 60715 35x7.5/15, occupying just 22.5 mm of panel width — a single module slot. The 74% efficiency figure is typical for this class at full load; at lighter draws it runs cooler, which matters when you stack several units in a sealed enclosure.
The 0.5 A output at 24 V DC (12 W) is sized for small control loads: a handful of relays, a compact PLC, or a few sensors. It is not a motor-starter supply. The input accepts 120-230 V AC, 47-63 Hz, which covers single-phase mains globally. The internal fuse is a non-accessible T 2 A/250 V — if it blows, the unit is replaced, not repaired. The I²t rating of 0.3 A²·s tells you the inrush energy the output can handle; keep the capacitive load on the 24 V bus under that threshold to avoid nuisance tripping on power-up.
Snaps onto DIN rail EN 60715 35x7.5/15. The 22.5 mm width means it takes one standard module position — useful when you are filling a crowded row. Input terminals: L, N, PE each accept one 0.5-2.5 mm² conductor. Output side: one terminal for +, two terminals for - (allowing daisy-chain return wiring). The recommended upstream protection is a 3 A characteristic C miniature circuit breaker.