What the interrupting ratings mean for your panel
The Siemens 3VA2340-6JP32-0CA0 is a SENTRON molded case circuit breaker (MCCB) rated for 400 A continuous current, with a 3-pole construction and line protection design. Its interrupting capacity of 242 kA at 240 V and 187 kA at 415 V means it can safely clear fault currents at those levels without welding contacts or rupturing the case — critical for high-fault installations like large transformer secondaries or industrial switchboards where available fault current exceeds what a standard MCCB can handle. At 690 V the rating drops to 7.5 kA, so verify the available fault current at your system voltage before specifying.
Thermal derating — the real continuous current
The 400 A continuous rating holds from 40 °C up to 50 °C ambient. Above that it derates: 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. If your panel ambient runs at 60 °C, the breaker is good for 350 A continuous — not the full 400 A. The maximum power loss is 98.5 W, which factors into enclosure thermal calculations.
Built-in undervoltage release and communication
This variant includes an undervoltage release (UVR) that trips the breaker when supply voltage drops below a set threshold — useful for preventing motor re-acceleration after a dip. It also has a communication function for remote monitoring or trip indication, though it ships without an auxiliary switch or ground-fault monitoring module. The basic switch version is 3VA2340-6JP32-0AA0 if you need the bare breaker without the UVR.