The Siemens SENTRON 5SP3763-3 is a 1-pole miniature circuit breaker rated 63 A at 230 V AC, 50 Hz, with an E tripping characteristic and a 25 kA breaking capacity per EN 60898.
The E characteristic (between standard B and C curves) trips at 10–20× rated current, so it's suited for circuits feeding small motors, pumps, or lighting ballasts that draw a brief startup surge a B-curve would misread as a fault.
Accepts solid or stranded copper from 2.5 mm² up to 50 mm² at the saddle terminals — enough for the full 63 A without pigtailing. The 76.3 mm depth fits standard 80 mm deep enclosures; the 128 mm height is within the usual 2-row DIN rail spacing. Integrated locking slide accepts a padlock, wire seal, or cable tie for lockout/tagout. The sealable cover (yes) lets you secure the toggle position after commissioning — useful for circuits that must stay locked on or off during maintenance.