The Siemens SENTRON 5SP3320-3 is a 3-pole miniature circuit breaker (MCB) rated 20 A at 400 V AC, with a 25 kA breaking capacity per EN 60898. It carries the type E tripping characteristic — a delayed curve that handles inrush from transformers or motor starters without nuisance trips, while still clearing a hard short fast. Out here in the grease, that means it won't pop when a pump kicks on, but it'll still save the wire if something goes wrong.
Ratings and what they mean for the panel
Rated 20 A at 30 °C, the breaker derates to 19 A at 40 °C, 18.5 A at 45 °C, and 18 A at 50 °C. If your panel runs hot — and most do — plan the load at the derated value, not the nameplate 20 A. The 25 kA breaking capacity at 400 V per EN 60898 means it can interrupt a fault up to that level without welding contacts or scattering arc products; that's enough for most commercial and light industrial service entrances. Insulation voltage rated at 690 V, overvoltage category IV, pollution degree 3. That's the heavy-duty end of the residential/infrastructure spec — suitable for main distribution panels where the breaker sits close to the utility transformer and sees dirty power.
Mounting and panel fit
Snaps onto standard DIN rail (35 mm). Occupies 4.5 modular width units — a bit wider than a standard 3-pole MCB (usually 3 MWUs), so check your DIN rail space before committing. Depth is 76.3 mm; height 128 mm. Accepts solid or stranded wire up to 50 mm², minimum 2.5 mm². Saddle terminals and box-terminal infeed are standard. IP40 with conductors connected; sealable with an integrated locking slide that accepts a lock, wire seal, or cable ties.
Lifecycle and sourcing
Listed as current production. No end-of-life notice or successor has been issued. The part is sourced to order against an RFQ through independent distribution; availability and current pricing are confirmed at quote time.