What this MCCB carries — and what it doesn't
The Siemens SENTRON 3VM1450-4EE32-0AA0 is a 3-pole molded case circuit breaker rated 500 A continuously at 40 °C, with full current hold through 50 °C — above that it derates linearly to 452 A at 70 °C. That thermal curve matters if this breaker lives in a hot panel next to a drive or transformer. The TM220 overcurrent release is a thermal-magnetic fixed-trip design: thermal element handles overloads, magnetic element clears short circuits. No trip indicator, no undervoltage release, no ground-fault monitoring — this is a straight line-protection breaker, not a multifunction feeder.
Breaking capacity — the number that decides selectivity
At 240 V AC this breaker interrupts 121 kA; at 415 V and 440 V it holds 76 kA; at 500 V it drops to 53 kA. Those are the symmetrical fault-current ratings that govern whether this breaker coordinates with the upstream device. For a 500 A main on a 480 V panel, the 76 kA at 415 V gives headroom above typical utility transformer impedances. The rated insulation voltage is 800 V, operating voltage 690 V AC — so it's spec'd for 600 V class systems with margin.
Panel fit — 110 mm depth, 138 mm width, IP40 front
The body measures 110 mm deep by 138 mm wide by 248 mm tall. That depth (110 mm) is the dimension that decides whether it clears a shallow enclosure backpan. Front protection is IP40 — finger-safe on the operator side, but no ingress protection on the rear or sides; mount it inside a sealed cabinet if the environment is dusty or wet. Power loss at rated load is 123 W maximum — account for that heat in the enclosure thermal calculation.