What this MCCB delivers
The Siemens 3VA2440-7JQ42-0AA0 is a SENTRON molded case circuit breaker rated for 400 A continuous current across the full operating temperature range from -25 °C to 70 °C — no derating needed up to 70 °C ambient. Four poles handle three-phase plus neutral or a second protected phase. The adjustable trip unit covers 600 A minimum to 6 000 A maximum, so you set the instantaneous pickup to match the downstream cable and load, not the other way around. Interrupting capacity is the headline: 330 kA at 240 V, 242 kA at 415 V and 440 V, 187 kA at 500 V, and 9 kA at 690 V. That 330 kA at 240 V means it clears a bolted fault on a 240 V secondary bus without the upstream transformer breaker needing to coordinate — it holds the arc contained inside the molded case. At 690 V the 9 kA figure is still adequate for most motor-circuit fault levels, but verify against your transformer impedance if you are feeding a 690 V drive line. The breaker includes a communication function for remote monitoring or trip-event capture, and a ground-fault monitoring version configured as summation current formation on L + N conductor — it sums the phase and neutral currents to detect leakage without a separate CT. No undervoltage release is fitted on this variant; if you need UVR for emergency-stop or undervoltage protection, that is a different order code in the 3VA2 family.
Panel fit and mounting
Dimensions: 248 mm high, 184 mm wide, 110 mm deep. That 110 mm depth is the body only — allow clearance for the rear terminals and any communication module plug-in. The 184 mm width for a 4-pole frame is standard for this class; it occupies four 45 mm module spaces on a DIN rail if using an adapter, or direct screw-mount on the backplate. Max power loss is 63.5 W, so factor that into enclosure thermal rise if the panel is sealed.