What this 4-pole MCCB delivers in the panel
The Siemens SENTRON 3VM1340-4GE42-0AA0 is a 4-pole molded case circuit breaker sized for line protection at 400 A continuous (rated at 40 °C, no derating needed until you cross 55 °C). It carries a TM220 thermal-magnetic overcurrent release — the thermal element handles overloads, the magnetic element clears short-circuit faults. Interrupting capacity is 121 kA at 240 V AC and 76 kA at 415/440 V, so it handles high-fault utility feeds or transformer secondaries without cascading upstream. That 400 A rating holds flat from 40 °C through 50 °C. At 55 °C it's 392 A; at 60 °C, 384 A; at 65 °C, 376 A; at 70 °C, 367 A. If your panel ambient runs hot — say next to a drive or transformer — you need that curve to size the breaker honestly, not the nameplate number.
Fit and footprint
The case measures 248 mm high, 184 mm wide, 110 mm deep. Four-pole width at 184 mm is standard for this class; verify the gland-plate knockout pattern and bus-bar centers before drilling the backplate. IP40 on the front keeps dust out of the mechanism — fine for a clean indoor panel, not for washdown.