Line protection MCCB with TM240 release
The Siemens SENTRON 3VA1340-4GF42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for line protection, carrying 400 A continuous at 40 °C and interrupting up to 121 kA at 240 VAC. The TM240 thermal-magnetic release handles overload and short-circuit curves without electronic adjustment — a fixed-trip design that simplifies specification for distribution panels where selectivity is set by frame size and cable impedance, not by dials.
Interrupting capacity across voltage levels
Breaking capacity drops with system voltage: 121 kA at 240 V, 75.6 kA at both 415 V and 440 V, 52.5 kA at 500 V, and 11.9 kA at 690 V. For a 400 V distribution board, the 75.6 kA figure covers most transformer-fed fault levels; the 690 V rating is worth noting for mining or marine installations where a single MCCB must clear a high-impedance fault on a 690 V bus.
Thermal derating and ambient limits
Rated 400 A through 50 °C ambient; above that the TM240 release derates linearly — 392 A at 55 °C, 384 A at 60 °C, 376 A at 65 °C, 367 A at 70 °C. Operating range is -25 °C to 70 °C, storage from -40 °C to 80 °C. In a crowded panel with multiple breakers ganged, the 55 °C derating column is the one to size against unless you have forced ventilation.
Physical fit and panel integration
Dimensions are 184 mm wide, 248 mm high, 110 mm deep — a 4-pole frame that occupies roughly 7.24 by 9.76 inches of panel face. No trip indicator, no undervoltage release, no communication module, and no ground-fault monitoring on this variant; it is a straight line-protection MCCB. The 92.1 W maximum power loss should be factored into enclosure thermal calculations, especially in a sealed stainless cabinet.