What this breaker carries
The Siemens 3VA1125-4GE42-0AA0-ZD00 is a 4-pole IEC frame 160 molded case circuit breaker with breaking capacity class S — rated Icu = 36 kA at 415 V AC. That interrupting rating means it can safely clear a fault up to 36 kA without welding its contacts or rupturing the arc chamber, which is the spec that governs whether it holds on a high-fault panelboard. It ships with a TM220 thermal-magnetic trip unit, fixed at In = 25 A, with overload protection adjustable Ir = 18 A to 25 A and instantaneous short-circuit pickup Ii = 12.8 × In (320 A at the 25 A setting). The N-conductor protection is set to 100 %.
Where it lands in a panel
This is a DIN-rail-mount MCCB sized for a 160 A frame, so it occupies the same footprint as other 3VA1 frame breakers. The 4-pole configuration covers three-phase-plus-neutral circuits — common in distribution panels feeding mixed single-phase and three-phase loads. The TM220 trip curve is thermal-magnetic: the thermal element handles sustained overloads (the Ir adjustment band), and the magnetic element clears short-circuit faults instantaneously at the Ii threshold. No electronic trip unit here, so no auxiliary power supply needed for the trip logic.