What this MCCB does on the line
The Siemens 3VA1140-4EF32-0JC0 is a SENTRON molded case circuit breaker (MCCB) rated for 40 A continuous at 40 °C, with three poles and a design focus on line protection — meaning it sits at the feeder or main distribution point, not on a motor branch. Its interrupting capacity hits 121 kA at 240 V and 75.6 kA at 415 V, which gives selectivity headroom downstream: you can coordinate a 25 kA panelboard behind this breaker without worrying about a fault cascading past the main. The unit includes a shunt trip (STL) release for remote emergency-off or supervisory tripping, and two auxiliary switches HQ for status feedback to a PLC or annunciator. No undervoltage release or ground-fault monitoring is fitted on this variant — those are separate order-code options if the application demands them.
Thermal derating and panel fit
The breaker holds its full 40 A rating up to 50 °C ambient; above that it derates gradually to 37 A at 70 °C. If the panel runs hot — say a packed enclosure with drives — that 37 A at the top of the range is the number to use for continuous load planning. The 70 mm depth and 76.2 mm width are standard for the 3VA1 frame, so it drops into a DIN-rail or screw-mounted footprint without re-drilling the backplate. Maximum power dissipation is 10.8 W, which is modest for a 40 A MCCB — useful to know when calculating enclosure ventilation. The rated insulation voltage of 800 V covers 480Y/277 V and 600 V delta systems with margin.