What it is and what it does
The Siemens 5SY4106-8CC is a SENTRON miniature circuit breaker (MCB) with a D tripping characteristic, designed to protect branch circuits against overloads and short circuits. The D curve means it tolerates high inrush currents — typically 10–20× the rated current — making it the right choice for motor starters, transformers, and other inductive loads that draw a heavy surge on startup. It is a single-pole unit rated for AC operation at 400 V (single-phase or multi-phase) and carries a 10 kA breaking capacity per EN 60898, which is the standard for household and similar installations. Under UL 1077 and CSA C22.2 No.235, the interrupting rating is 5 kA, so verify which standard governs your panel's listing.
Panel fit and integration
At 18 mm wide (one modular width unit), this MCB snaps onto a standard DIN rail via the quick assembly system and can be mounted in any position. Depth is 76 mm, installation depth 70 mm — check gland-plate clearance if the panel is shallow. The IP20 rating applies with connected conductors, so it's intended for enclosed distribution boards, not wet areas. Pollution degree 3 and overvoltage category III suit it for industrial control panels where conductive dust or transient surges are present. Combined terminals at top and bottom accept both busbar and wire, and the unit is sealable for anti-tamper applications.
Environmental and service life
Rated for ambient temperatures from -40 °C to 75 °C, with humidity derating above 55 °C (max 95% RH at 55 °C, tapering to 35% at 75 °C). Mechanical service life is 10,000 operating cycles typical. The housing is halogen-free and silicon-free, which matters for clean-room or food-grade panels where outgassing must be controlled. Power loss per pole is 1.2 W at rated current in hot operating state — negligible for thermal budgeting in a dense DIN-rail row.