What it is and where it fits
The Siemens 5SJ4101-8HG41 is a 1-pole SENTRON miniature circuit breaker from the 5SJ4 series, designed with a D tripping characteristic. It protects branch circuits in control panels and distribution boards against overload and short-circuit, rated for 400 V AC and 60 V DC. The D curve means it tolerates high inrush currents — typical for motor starters, transformers, or welding equipment — without nuisance tripping, while still clearing faults at its rated breaking capacities. Rated for pollution degree 3 and overvoltage category III, meaning it's suited for fixed industrial installations where conductive contamination is possible (e.g., machine enclosures, panel interiors). IP20 with conductors connected; IP40 in the handle area — enough for enclosed panels, not for washdown zones.
Breaking capacity and selectivity
This breaker carries two breaking-capacity ratings: 10 kA per EN 60898 (household-type MCB standard) and 15 kA per IEC 60947-2 (industrial standard). The higher IEC figure is the one that governs panel SCCR coordination in an industrial line — it means the breaker can safely interrupt a 15 kA prospective fault at 400 V AC without upstream devices needing to clear first. For DC circuits, the maximum rated voltage is 60 V DC. The D characteristic (10–20× In magnetic trip) pairs well with loads that draw a brief inrush several times the rated current — think motor contactors, solenoid banks, or power supplies. For purely resistive or lightly inductive loads, a B or C curve would trip faster; the D curve is the right call where nuisance trips on start-up are the main concern.
Lifecycle and sourcing
Production status is current — this is an active catalog item, not a phase-out or NRND line. The 5SJ4 series remains Siemens' standard offering for panel-protection in the SENTRON family. Sourced and quoted to order against an RFQ through independent distribution; availability and current pricing confirmed at quote time.