What this MCCB carries and where it fits
The Siemens SENTRON 3VM1340-4ED42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated 400 A at 40 °C, with a TM210 thermal-magnetic overcurrent release. The TM210 designation means the thermal element is fixed at 400 A (the Iu rating) and the magnetic short-circuit pickup is adjustable up to 4000 A — that's 10× In, which gives you room to ride through motor inrush without nuisance tripping on a feeder or distribution circuit. Breaking capacity is 121 kA at 240 V AC, 76 kA at 415/440 V, and 53 kA at 500 V. That's a high-interrupting rating for a 400 A frame — it handles fault currents on the secondary side of a large transformer or a high-capacity bus without needing a current-limiting fuse upstream. The 690 V rated insulation voltage (Ui) and 500 V max DC operational rating (Ue) confirm it for 480/600 VAC industrial panels and some DC distribution applications. The front face carries IP40 protection — splash protection isn't built in, so keep it inside a panel enclosure. Dimensions are 248 mm high, 184 mm wide, 110 mm deep, which fits standard SENTRON mounting footprints for 4-pole frames in switchgear assemblies.
Thermal derating and power loss
The 400 A rating holds up to 50 °C ambient. Above that it derates linearly: 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 W — a factor for panel thermal budgeting if you're stacking multiple breakers in a sealed enclosure.
What the TM210 release means for coordination
The TM210 is a thermal-magnetic release with a fixed thermal element (the 400 A Iu) and an adjustable magnetic pickup (li) from 2000 A to 4000 A. That adjustability is the key selectivity tool: you set the magnetic threshold high enough to pass downstream branch breaker instantaneous trips, but low enough to protect the feeder cable. The fixed thermal element means you can't down-rate the continuous current — this breaker is sized for a 400 A circuit, not a 250 A one you might want to dial back.
Panel integration notes
Mounts on a standard DIN rail or direct-panel mount via the SENTRON base. No communication function or motor drive option is fitted on this variant — it's a standalone thermal-magnetic breaker, not a remote-controlled or metering unit. Ground-fault monitoring and N-conductor protection are also absent, so plan external GFCI or neutral protection if the application requires it.