What it is and what it does
The Siemens SENTRON 3VA1140-4EF32-0HH0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, with a rated continuous current Iu of 40 A and a rated insulation voltage Ui of 800 V. It carries a TM240 thermal-magnetic overcurrent release and includes a shunt trip (STL) auxiliary release for remote tripping. The breaker is fitted with two auxiliary switches plus one trip alarm switch (HQ configuration), giving you feedback on position and fault state without extra wiring. The short-circuit breaking capacities are rated across four voltage levels: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 690 V. That spread covers most industrial distribution voltages — the 415 V figure is the one to watch for common European 400 V panels; the 690 V rating handles high-voltage motor circuits where available fault current is lower.
Thermal rating and derating
The breaker holds its full 40 A rating from 40 °C up to 50 °C. Above that, derating is gradual: 38.4 A at 55 °C, 37.6 A at 60 °C, 36.8 A at 65 °C, and 36 A at 70 °C. If your panel ambient sits at 55 °C or higher, you lose roughly 1.6 A per 5 °C step — factor that into the load calculation rather than oversizing the frame.
Physical fit and panel integration
Dimensions are 130 mm height, 76.2 mm width, 70 mm depth. The width is a standard 3-pole MCCB footprint — it fits a 76.2 mm cutout in most panel layouts. Protection class IP40 on the front means it is splash-proof from the operator side but not sealed against dust ingress through the enclosure; mount it in a panel with at least IP54 overall if the environment is dusty.
Environmental limits
Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. The storage limit governs handling and warehousing — the breaker can sit in a cold warehouse at -40 °C without damage, but it must be above -25 °C to be switched under load.