What it is and what it does
This Siemens 3VA2440-7MS32-0JA0 is a 3-pole IEC frame 630 circuit breaker with a breaking capacity class C rating of Icu=110 kA at 415 V. It's built around the ETU310M trip unit, set for a rated current In=400 A, and configured for starter protection — meaning it handles short-circuit protection (adjustable Ii=3...15 x In) but omits overload protection, leaving that to an external overload relay. The integrated shunt trip on the left side operates on 110-127 V AC 50/60 Hz or DC, so you can remotely trip the breaker from a safety circuit or emergency stop chain.
Where it lands in the panel
This breaker mounts on a DIN rail inside the main distribution panel. The nut keeper kit helps secure the busbar connections, which is a small detail that saves time during assembly. The shunt trip occupies the left accessory slot — verify clearance if you're also fitting an auxiliary switch or alarm contact on the right side.