What it is and what it does
The Siemens SENTRON 5SL3101-7 is a 1-pole miniature circuit breaker (MCB) with a C-curve trip characteristic, rated 1 A at 230/400 V AC. It occupies a single modular width unit (18 mm) on a DIN rail and is designed for branch-circuit protection in residential and light-commercial distribution boards. The C-curve means it trips between 5 and 10 times the rated current — standard for protecting inductive loads like small motors, lighting ballasts, and transformer primaries where inrush is moderate. Breaking capacity is 4.5 kA per EN 60898 and 5 kA per IEC 60947-2 at 400 V AC. That 5 kA figure under the industrial standard (IEC 60947-2) is the one to use when the breaker sits in an industrial panel with higher prospective fault current — the EN rating governs domestic consumer units.
Where it fits and how it mounts
Snaps onto standard 35 mm DIN rail. At 18 mm wide (1 MW), it leaves room for adjacent breakers, RCDs, or auxiliary contacts in a crowded enclosure. Mounting position is unrestricted — any orientation works. Installation depth is 70 mm; overall depth including terminals is 76 mm. That 6 mm difference is the terminal screw projection — factor it into your enclosure depth clearance. Rated IP20 with connected conductors — protected against finger contact but not moisture. Suitable for dry indoor enclosures only; no washdown or outdoor exposure.
Key ratings at a glance
Rated 1 A at 230 V single-phase (line-to-neutral) and 400 V multi-phase (line-to-line). Frequency 50/60 Hz. Overvoltage category III, pollution degree 2 — standard for fixed-installation distribution boards. Mechanical service life is 10,000 operating cycles typical. Power loss per pole at rated current in hot state is 1.2 W — negligible thermal contribution in a populated enclosure. Energy limitation class 3 means it limits let-through energy effectively, reducing stress on downstream equipment during a fault. Accepts supplementary devices (auxiliary switches, shunt trips, alarm contacts) via the accessory slot.