The Siemens SENTRON 5SY8205-7 is a 2-pole miniature circuit breaker (MCB) from the 5SY8 series, rated at 0.5 A with a C tripping characteristic. It provides a 70 kA breaking capacity at 400 V AC per IEC 60947-2, giving substantial fault-current headroom for industrial panel feeders where high prospective short-circuit currents are expected.
Breaking capacity and coordination
The 70 kA rated short-circuit breaking capacity (Icu) at 400 V AC means this breaker can safely interrupt faults up to that level without upstream devices needing to clear the fault — critical for selectivity in main distribution boards or sub-distribution where the available fault current is high. At DC, the rated breaking capacity is 15 kA per IEC 60947-2, and under UL 1077 / CSA C22.2 No. 235 it carries a 5 kA interrupting rating at AC. The C-curve (tripping characteristic class C) means magnetic trip occurs at 5 to 10 times rated current, suited for moderate inrush loads like small motor starters, contactor coils, or control transformers where a B-curve would nuisance-trip but a D-curve is unnecessary.
Mounting and panel integration
Snaps onto DIN rail via the quick assembly system; occupies 2 width units (36 mm) in the enclosure. Mounting position is any, so it fits horizontal or vertical busbar arrangements without derating. Installation depth is 70 mm, with an overall depth of 76 mm including the terminal arc. Terminal capacity accepts solid or stranded conductors from 0.75 to 35 mm², with a tightening torque of 2.5 to 3.5 N·m for screw-type terminals. Combined terminals top and bottom simplify daisy-chaining.
Environmental and compliance
Rated for ambient temperatures from -25 to +55 °C, with storage from -40 to +75 °C. The housing is halogen-free and silicon-free, important for environments sensitive to outgassing (e.g., clean rooms, medical, or semiconductor support areas). Protection class is IP20 with connected conductors — standard for enclosed panel mounting. Touch protection is integrated. The part carries an overvoltage category III rating, suitable for fixed installation downstream of the main distribution board.