The Siemens 5TT5540-0CC is a SENTRON OUPA overvoltage undervoltage fused switch in a 1P+N design. It carries a 40 A rated operational current at AC and is rated for 230 V AC only — that 40 A at 230 V is the full-load switching capacity for this single-pole-plus-neutral form factor.
At 36 mm width and 2 modular width units, this switch occupies two standard 18 mm DIN-rail module spaces. The single NO contact (no NC, no CO) is the auxiliary signal output — it closes when the device trips, giving a remote status indication. The 230 V AC operating coil draws from the line it protects; no separate control supply needed.