What it is and what the ratings mean
The Siemens 3VA1225-4FF42-0KA0 is a 4-pole IEC frame 250 molded case circuit breaker from the 3VA1 series, configured for line protection with a TM240 thermal-magnetic trip unit. The 36 kA breaking capacity at 415 V (class S) means it safely interrupts fault currents up to that level without upstream cascading — critical for panel selectivity in industrial distribution. The TM240 trip provides adjustable overload protection (Ir = 175–250 A) and fixed short-circuit pickup (Ii = 5–10 × In), letting you dial in the continuous current to match the downstream load without swapping the breaker body.
Built-in shunt trip and N-conductor protection
This variant ships with a factory-installed shunt trip on the left side, rated 208–277 V AC 50/60 Hz and 220–250 V DC. That remote-trip capability is typical for emergency-stop circuits or remote shutdown in conveyor and pump panels. The N-conductor protection at 50% means the neutral pole trips at half the phase-pole setting — common for 4-wire systems where neutral current is limited by harmonic content. The nut keeper kit is included for secure panel-mounting on the DIN rail or direct plate.