What the 70 kA SCCR means for your panel
The Siemens 5SY8205-8 is a 2-pole SENTRON miniature circuit breaker with a D tripping characteristic, rated 0.5 A at 400 V AC. The D-curve (10–20× In magnetic trip) is deliberate: it rides out the inrush of a small transformer, solenoid bank, or motor starter without nuisance tripping, then clears fast on a hard fault.
Thermal derating and environmental range
The 0.5 A rating is at 45 °C ambient. At 50 °C it derates to 0.48 A, and at 55 °C to 0.47 A — a linear drop of about 4% per 5 °C step. The operating range spans -40 °C to 75 °C, with humidity limits of 95% at 55 °C, tapering to 35% at 75 °C. That wide thermal envelope suits unheated enclosures or outdoor cabinets in temperate to hot climates.
Snap-on quick assembly system, mountable in any position. Touch protection is built in, so no additional finger-safe shrouds needed for the front panel.
DC and UL ratings
For DC circuits per IEC 60947-2, the breaking capacity is 15 kA. Under UL 1077 and CSA C22.2 No. 235 (supplementary protector recognition), it is rated 5 kA at 400 V AC. Vibration resistance per IEC 60068-2-6: ±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz. These ratings confirm it for industrial machinery panels that see moderate vibration from nearby drives or conveyors.