The Siemens 5SY8201-7 is a SENTRON miniature circuit breaker (MCB) — a 2-pole, C-curve unit rated 1 A at 440 V AC multi-phase, with a 70 kA breaking capacity per IEC 60947-2.
The C-curve (tripping characteristic class C) means it holds 5–10× rated current momentarily before tripping — typical for motor-starting or transformer inrush where you need a little headroom. At 1 A rated, it's sized for a control transformer primary, a small pump motor, or a lighting subcircuit. The 70 kA IEC 60947-2 rating covers AC fault conditions; on DC circuits it's rated 15 kA up to 72 V — enough for battery-backed control power or DC bus protection.
Environment and mounting
That -40 °C floor is unusual for an MCB and matters for unheated enclosures or cold-storage lines. Halogen-free and silicon-free construction, so it won't outgas in sensitive electronics areas. Depth is 76 mm (70 mm installation depth), height 90 mm — check your gland-plate clearance.