What this MCCB carries — and what that means for your panel
The Siemens 3VA1332-7EF32-0AH0 is a SENTRON molded case circuit breaker (MCCB) built for high-fault-duty distribution and motor branch circuits. Three poles, rated 320 A continuous at 40 °C, with a TM240 thermal-magnetic trip unit — the thermal element handles overloads, the magnetic element clears short-circuits. The headline number is the interrupting rating: 440 kA at 240 V AC. That is not a typo — this is a current-limiting MCCB designed for installations where available fault current is extreme, typically downstream of large transformers or in heavy industrial switchgear. At 415 V it still clears 242 kA, and at 690 V it holds 17 kA, which covers most 690 V industrial networks.
Ratings that decide the fit
Rated insulation voltage (Ui) is 800 V, so the breaker is rated for 690 V systems with margin. The 320 A rating holds flat from 40 °C through 50 °C — no derating needed in a warm enclosure up to that point. At 55 °C it derates to 313 A, at 60 °C to 306 A, at 65 °C to 299 A, and at 70 °C to 292 A. If your panel ambient runs hot, that derating curve is the real-world rating to size against. Power loss at rated load is 80.1 W maximum — relevant for enclosure thermal calculations, especially in a sealed or high-density panel. The breaker includes 2 auxiliary switches plus 1 trip alarm switch (HQ design), which gives remote status indication without an add-on module.
Physical footprint and integration
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. That 110 mm depth is the body only — allow for handle throw and wiring space behind the panel door. The 138 mm width is standard for a 3-pole frame in this class; verify your existing busbar or cable lug spacing against the terminal centers before committing the drill pattern.