What this MCCB is and what the ratings mean for your panel
The Siemens SENTRON 3VA2140-7JQ42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for 40 A continuous current, designed for line protection in distribution panels. Its 330 kA breaking capacity at 240 V means it can safely interrupt a fault current up to that level without welding contacts or cascading failure upstream — critical for high-fault installations like transformer secondaries or large motor control centers. At 415 V and 440 V it still holds 242 kA, dropping to 187 kA at 500 V and 3.7 kA at 690 V, so the voltage-dependent rating governs where you place it in the system. The 40 A rating holds flat across the full operating temperature range from -25 °C to 70 °C — no derating curve to chase. That simplifies panel layout in warm enclosures or outdoor cabinets. Insulation voltage is rated 800 V, so it handles 480/277 V systems with margin. It includes a ground-fault monitoring function using summation current formation on L + N conductors, and a communication function for integration into a higher-level monitoring system — useful for predictive maintenance or remote trip indication on a critical feeder.
Mounting and panel fit
Dimensions are 86 mm deep, 140 mm wide, 181 mm tall — a standard MCCB footprint for a 4-pole 40 A frame. Mounts on a DIN rail or directly to a backplate via the fixed contacts. The 140 mm width means it occupies roughly three 45 mm module spaces, so plan your enclosure fill factor accordingly. No undervoltage release or voltage trigger on this variant — it's a straight thermal-magnetic or electronic trip unit with ground-fault summation.