The Siemens 5SY7220-8 is a SENTRON miniature circuit breaker — 2-pole, D-curve, 20 A rated at 35 °C, breaking 15 kA per EN 60898-1 and 25 kA per IEC 60947-2. That D characteristic means the magnetic trip fires between 10× and 20× In, so it handles the high inrush of motor-starting loads or transformer primaries without nuisance trips. The 25 kA IEC rating gives headroom on industrial panels with high fault-current availability; the 15 kA EN rating covers residential or light-commercial distribution boards.
Mounting & panel fit
Width is 36 mm (2 modular units), depth 76 mm, height 90 mm. Snaps onto DIN rail via the quick-assembly system; mounting position any. Installation depth 70 mm. The combined top/bottom terminals accept the same conductor range — no need to flip the breaker for feed direction. Sealable cover is standard, so it can be locked or tagged in safety-disconnect positions.
Thermal derating & environment
Rated 20 A at 35 °C; derates to 18.78 A at 40 °C, 18.14 A at 45 °C, 17.48 A at 50 °C, 16.8 A at 55 °C, and 16.08 A at 60 °C. Ambient range -40 °C to +75 °C. Pollution degree 3, overvoltage category III. Halogen-free and silicon-free construction — relevant for clean-room or controlled-atmosphere panels. Humidity tolerance: 95% up to 55 °C, then derated to 55% at 70 °C and 35% at 75 °C.
Compliance & lifecycle
Current-production part (lifecycle stage: current). Complies with IEC/EN 60898-1 and IEC/EN 60947-2 / UL1077. No neutral conductor switching (2-pole, both poles protected). Suitability marked for mechanical engineering and general industry. IP20 with connected conductors. The product designation follows EN 61346-2 and IEC 81346-2 function code F.