Siemens 5SP3216-3 SENTRON — 2-pole E-curve MCB at 400 V
The Siemens 5SP3216-3 is a 2-pole main miniature circuit breaker from the SENTRON family, rated at 400 V AC with a 25 kA breaking capacity per EN 60898. The E tripping characteristic is designed for applications requiring delayed overload response — typically feeder protection in residential and infrastructure panels where inrush currents from transformers or long cable runs need to ride through without nuisance tripping. Snaps onto 35 mm DIN rail per EN 60715 and occupies 3 modular width units. The enclosure is rated IP40 with conductors connected, suitable for enclosed distribution boards. Pollution degree 3 and overvoltage category IV mean it's rated for the harsh end of the mains interface — think service entrance or main switchboard positions, not just final subcircuits.
E-curve selectivity and coordination
The E characteristic sits between the standard B/C curves and the selective S curve. At 400 V, the 25 kA breaking capacity gives solid headroom for most residential and light commercial service entrances. The 690 V rated insulation voltage (Ui) and 6 kV surge voltage resistance confirm the part is built for main-panel duty, not just branch protection. For a 2-pole main breaker at this voltage class, the 25 kA SCCR is the number that governs coordination with the upstream transformer — it interrupts faults up to that level without cascading.
Panel integration and wiring
Terminals accept solid or stranded conductors from 2.5 mm² up to 50 mm² — sized for the main feeder, not just tap conductors. Saddle terminals and box-terminal infeed are standard. The integrated locking slide accepts a padlock, wire seal, or cable tie for lockout/tagout. Depth is 76.3 mm, height 128 mm — check the gland plate clearance if the panel is shallow; the 3-module width is standard for a 2-pole main breaker on DIN rail.
Environmental and mechanical ratings
Rated for ambient temperatures from -40 °C to +70 °C, covering unheated enclosures and outdoor-adjacent installations. Shock resistance is 30 g for 11 ms duration, vibration resistance 2 g across 5–150 Hz per IEC 60068-2-6. Mechanical service life is 20,000 operating cycles typical. The switch position indicator shows green for OFF, red for ON — a quick visual check without opening the panel door.