The Siemens SENTRON 5SY5450-7CC is a 4-pole miniature circuit breaker rated for 880 V DC with a 10 kA breaking capacity per IEC 60947-2. The C-curve tripping characteristic (5–10× In) makes it suitable for moderate inrush loads like motor control circuits and industrial DC supplies where you need selectivity against downstream faults. The 50 A rating covers the common DC bus size for a mid-range drive or a distribution subfeed in a 24–48 V control cabinet converted to 880 V PV string combiner boxes.
DC ratings and breaking capacity
Rated 880 V DC with a maximum of 1 000 V DC — this covers the nominal voltage of most utility-scale solar arrays (typically 600–1000 Vdc) and industrial DC link circuits. The 10 kA breaking capacity at 880 V DC (IEC 60947-2) is the figure that governs fault clearing in a DC bus; at 400 V AC per UL 1077/CSA C22.2 No.235 it carries 5 kA. For a DC circuit, polarity must be observed on the supply cord — the breaker is not polarity-agnostic, so pre-wire with the marked line and load orientation.
IP20 with connected conductors — finger-safe front, but the terminals require the panel to be closed during normal operation.
Rated for ambient temperatures from -40 °C to +75 °C, with humidity derating above 55 °C (95% RH up to 55 °C, 55% RH up to 70 °C, 35% RH up to 75 °C). Pollution degree 2 (non-conductive dust, occasional condensation). Overvoltage category II — suitable for downstream distribution, not the main service entrance.