What this MCCB carries and where it fits
The Siemens SENTRON 3VA1140-6EF36-0DH0 is a 3-pole molded case circuit breaker rated 40 A at 40 °C, designed for line protection in distribution panels. Its interrupting capacity at 240 V AC is 220 kA, which means it can safely clear very high fault currents — typical for large transformer secondaries or industrial service entrances where available fault current is substantial. At 415 V it still holds 154 kA, and at 690 V it derates to 17 kA, so the voltage class of your system determines which breaking rating governs the installation. This unit ships with an undervoltage release (UVR) and two auxiliary switches plus one trip alarm switch (HQ). The UVR means the breaker trips automatically when control voltage drops below a threshold — common for emergency-stop circuits or undervoltage protection on motor feeders. The auxiliary contacts let the panel PLC or SCADA read the breaker's open/closed status and the trip alarm signals a separate fault indication. Physically it occupies 76.2 mm width (3 in) on the DIN rail or panel-mount footprint, 130 mm height, 70 mm depth. The rated insulation voltage is 800 V, so it's suitable for 690 V systems with margin. Maximum power loss at rated current is 13.3 W — relevant for thermal management inside a sealed enclosure.
Thermal derating and operating range
The breaker holds its full 40 A rating from 40 °C up to 50 °C ambient. At 55 °C it derates to 39 A, at 65 °C to 38 A, and at 70 °C to 37 A. For a panel that runs hot — say 55 °C inside — you lose only 1 A of headroom, so the 40 A frame still covers most 32 A or 36 A loads without upsizing. The operating ambient range is -25 °C to 70 °C, storage from -40 °C to 80 °C.