What it is and what it does
The Siemens 5SY4100-7XX02 is a 1-pole SENTRON miniature circuit breaker (MCB) with a C-curve tripping characteristic rated at 2.5 A. It protects branch circuits against overload and short-circuit in industrial control panels, distribution boards, and machinery — the C-curve means it tolerates moderate inrush (5–10× rated current), so it suits mixed resistive-inductive loads like contactor coils, small transformers, and motor starters where a B-curve would nuisance-trip on energisation.
Breaking capacity — what the ratings mean for fit
Three breaking-capacity figures govern where this MCB can be installed. Under EN 60898 it is rated 10 kA — that is the standard for final circuits in residential and light commercial distribution boards where the prospective short-circuit current (PSCC) stays under 10 kA. Under IEC 60947-2 it carries 35 kA, which qualifies it for industrial panels where fault levels are higher; the 60947-2 standard covers performance under industrial conditions (pollution degree 3, overvoltage category III). Under UL 1077 and CSA C22.2 No. 235 it is rated 5 kA, so it can serve as a supplementary protector in North American equipment — but not as a branch-circuit main (that requires a UL 489 listing). The buyer must match the applicable standard to the jurisdiction and the panel's available fault current.
Voltage and duty
Rated 400 V AC (50/60 Hz) and 72 V DC maximum. On a single-pole MCB the DC rating is important — many 1P breakers are AC-only; this one handles DC circuits up to 72 V, so it can protect a 48 V DC control supply or a 24 V DC bus. The multi-phase AC rating goes to 440 V, meaning it can be used in 3-phase 400 V systems with one pole per phase. The auxiliary switch (1 NO + 1 NC) integrated into the design allows remote status monitoring — a common requirement for PLC-based fault annunciation or for signalling a tripped breaker in an automated line.
Panel fit and environment
Width is 27 mm (1 width unit), depth 76 mm, installation depth 70 mm. Mounts on a DIN rail via the quick-assembly system — snap-on, no tools. Any mounting position is allowed, which simplifies panel layout. IP20 with connected conductors (finger-safe when wired). Operating temperature range -40 °C to 75 °C, with derating for humidity: max 95% RH at 55 °C, tapering to 35% RH at 75 °C. Halogen-free and silicon-free construction matters for environments where outgassing can contaminate contacts or optics (e.g., clean rooms, semiconductor fabs). Sealable terminals are available for anti-tamper requirements.