400 A MCCB for main feeder or large motor protection
The Siemens 3VA1340-4EE42-0AA0 is a SENTRON molded case circuit breaker rated for 400 A continuous current (Iu) at up to 50 °C ambient, with a 4-pole configuration and TM220 thermal-magnetic release. It carries a 121 kA interrupting rating at 240 V AC, which drops to 76 kA at 415 V and 440 V, then to 53 kA at 500 V, and 10.5 kA at 690 V — so the available fault current at your service voltage determines whether this breaker clears without upstream coordination. The TM220 release means the thermal element is fixed at 400 A; the magnetic pickup is adjustable, typically 5–10x In for the 3VA platform, letting you dial in motor start or transformer inrush without nuisance trips.
Current derating and thermal budget
Above that, it derates: 392 A at 55 °C, 384 A at 60 °C, 376 A at 65 °C, and 367 A at 70 °C. Maximum power loss is 92.1 W, which matters for enclosure heat rise calculations when grouping multiple breakers.
Mounting dimensions and panel fit
The breaker measures 184 mm wide by 248 mm high by 110 mm deep. That depth includes the handle and arc chamber — verify your enclosure depth clears 110 mm plus wiring bend radius on the line and load lugs. The 4-pole body is wider than a 3-pole; confirm your DIN-rail or bolt-on mounting plate has the 184 mm slot free.
Voltage ratings and application range
Maximum DC operational voltage is 600 V — usable in some battery or DC bus applications, but consult the 3VA DC manual for specific series/parallel pole wiring. The line protection designation means it's configured for cable and busbar protection out of the box; motor protection would typically use a different release curve or an electronic trip unit.