The Siemens 5SY4320-7CV is a 3-pole miniature circuit breaker (MCB) rated for a 20 A C-trip curve with a 15 kA interrupting capacity (Icu) at 400 V AC. That 15 kA rating means it can safely clear a bolted fault up to that level without welding its contacts or rupturing the case — critical for downstream coordination in a panel feeding motor starters or distribution subfeeds where available fault current is high.
Snap-on DIN rail mount, standard 3-module width. The C20 curve handles moderate inrush from motor starters or small transformers — typical for a panel-fed machine cell where the load isn't purely resistive. The 15 kA Icu at 400 V matches the SCCR requirement for most industrial control panels built to UL 508A; verify the let-through of the upstream device to keep the series rating intact.