The 5SY4620-8CV is a 4-pole miniature circuit breaker with a D tripping characteristic, rated 20 A at 35 °C and carrying a 15 kA breaking capacity per IEC 60947-2. The 4-pole design with switched neutral (3+N) suits three-phase four-wire systems where you need to break all live conductors on a fault. Mounting position is unrestricted, and the quick-assembly system speeds rail installation.
The 15 kA breaking capacity at 440 V AC (multi-phase) per IEC 60947-2 is the key selectivity number. In a panel with a 25 kA prospective short-circuit current, you'd need a current-limiting upstream device — this breaker alone won't clear that. The D curve's magnetic trip at 10–20× In (200–400 A for the 20 A frame) is what makes it the go-to for motor branch circuits; a 7.5 kW motor on a 20 A D-curve MCB holds the start and trips on a locked-rotor event. Temperature derating matters in a warm panel. At 35 °C it's a full 20 A; at 40 °C it drops to 18.54 A, at 50 °C to 16.9 A, and at 55 °C to 16.08 A. If your panel ambient hits 50 °C, that 20 A breaker is effectively a 17 A device — size up if the continuous load is near the nameplate. The humidity limits follow a similar curve: max 95% RH up to 55 °C, then derating to 35% at 75 °C. The vibration resistance (±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz per IEC 60068-2-6) covers the typical shake on a machine-mounted panel.
The breaker is certified to IEC / EN 60947-2, the standard for low-voltage switchgear and controlgear. The functional designation per IEC 81346-2 and EN 61346-2 is F — protective device. This is the same compliance package the brand provides for the entire 5SY series; no separate UL or CSA listing is stated in the spec record.