What these ratings mean for your panel
The Siemens 5SY4402-5 is a 4-pole SENTRON miniature circuit breaker with a 2 A rated current at 400 V AC and tripping characteristic class A — meaning it trips on very low overcurrents, suited for protecting semiconductor or sensitive electronic loads. If your BOM called for a 4P breaker in this frame, the 2 A rating is the first check: verify your load draw stays well under 2 A continuous.
Lockout and isolation — show me the rating
The 5SY4402-5 is sealable — it accepts a padlock hasp for positive lockout/tagout. If it's not locked, it's not safe. The IP20 rating (with conductors connected) means finger-safe terminals; pollution degree 3 covers industrial environments where conductive dust or moisture is present. Overvoltage category III confirms it can handle distribution-level transients on the line side.
Mounting and enclosure fit
Depth is 76 mm, width 72 mm, height 90 mm — 4 modular width units (4 M). Mounting position any, fastening is via the quick assembly system (standard DIN rail). Installation depth 70 mm; vibration resistance tested to ±1 mm at 5–25 Hz and 50 m/s² at 25–150 Hz. Temperature range -40 °C to 75 °C.
Breaking capacity — match your SCCR
Breaking capacities: 10 kA, 35 kA AC, 15 kA DC, 5 kA (UL/CSA). Verify system SCCR does not exceed the applicable rating. Supply frequency 50/60 Hz; rated voltage 400 V AC (440 V multi-phase).