MCCB with a real derating curve
The Siemens 3VA1140-6EF36-0AC0 is a SENTRON 3-pole molded case circuit breaker rated for 40 A continuous at 40 °C ambient, with a TM240 thermal-magnetic overcurrent release. The breaking capacity is 220 kA at 240 V, stepping down to 154 kA at 415 V and 121 kA at 440 V — still 17 kA at 690 V, which covers most industrial distribution voltages. The insulation voltage is rated 800 V. The temperature derating is non-trivial: holds 40 A from 40 °C through 50 °C, drops to 39 A at 55 °C and 60 °C, then 38 A at 65 °C, and 37 A at 70 °C. If your panel ambient runs hot, the 40 A label isn't the number you size to — the 37 A at 70 °C is. The maximum power loss is 10.8 W — relevant for enclosure thermal budgeting when grouping multiple breakers.
Panel fit and build
Dimensions are 130 mm height, 76.2 mm width, and 70 mm depth. The 3-pole footprint is standard for SENTRON 3VA MCCBs — fits existing panel cutouts and busbar layouts designed for the series. Comes factory-fitted with two auxiliary switches HQ. No undervoltage release, no ground-fault monitoring, no communication module — this is a line-protection breaker, not a power-monitoring device.