What this 400 A MCCB delivers on the line
The Siemens SENTRON 3VA2340-7KQ42-0AA0 is a 4-pole molded case circuit breaker rated for 400 A continuous at 40 °C, with an ETU860 electronic trip unit for line protection duty. Its interrupting capacity hits 330 kA at 240 V, 242 kA at 415 V, and 187 kA at 500 V — numbers that give an electrical engineer headroom for high-fault panels without cascading upstream breakers. The 400 A rating holds flat through 50 °C, then derates to 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. That thermal curve matters when the breaker sits in a crowded enclosure with other heat sources — the 50 °C plateau buys headroom most MCCBs in this frame size don't offer. The ETU860 electronic trip unit provides adjustable long-time, short-time, instantaneous, and ground-fault protection. Ground-fault monitoring uses summation current formation on L+N conductors. Communication function is built in — this breaker talks to the control system without an add-on module.
Panel fit and integration
Dimensions are 248 mm high, 184 mm wide, 110 mm deep — a 4-pole frame. The IP40 front protection means it's suited for enclosed distribution boards. The optional motor drive extension (product extension optional) allows remote charging and closing — useful for a panel where the breaker is mounted in a back-of-cabinet location or integrated into an automatic transfer scheme.