The Siemens 5SY4616-8CV is a 3-pole-plus-neutral miniature circuit breaker with a D16 tripping characteristic and a rated ultimate breaking capacity (Icu) of 15 kA at 400 V AC.
The 15 kA Icu at 400 V gives selectivity headroom in a panel fed by a larger upstream breaker — you can coordinate downstream faults without cascading. The 3P+N format suits three-phase four-wire systems (TN-S or TN-C-S) where the neutral is switched. Snap onto standard DIN rail in a distribution board or motor control center.