What this MCCB is and what it does
The Siemens 3VM1140-3EE32-0AA0 is a 3-pole molded case circuit breaker (MCCB) from the SENTRON family, designed for line protection in distribution panels. It carries a TM220 thermal-magnetic overcurrent release — the thermal element handles overloads, the magnetic element handles short-circuits — and is rated for a continuous current of 40 A at 40 °C ambient. The 76 kA breaking capacity at 240 VAC means it can safely interrupt fault currents up to that level without upstream fuses or a larger breaker, which simplifies panel coordination. On a 400 VAC line the interrupting rating drops to 53 kA; at 500 VAC it is still 12 kA, so the part covers most industrial service-entrance and feeder applications within its voltage class.
Current derating and thermal limits
The 40 A rating holds flat 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. The maximum operating temperature is 70 °C, with a minimum of -25 °C. Storage range is -40 °C to 80 °C. The 11 W maximum power loss at rated current is modest — no special ventilation required in a standard IP40 enclosure, though the front face is rated IP40, meaning tools or fingers over 1 mm diameter are kept out. The insulation voltage is rated 800 V, so the breaker can be used in 690 VAC systems with appropriate derating.
Panel integration and mounting
The breaker occupies a 76.2 mm wide by 130 mm tall by 70 mm deep footprint — three standard 25 mm DIN modules wide. It mounts on a DIN rail via the integral snap-on latch. The front face is IP40, so it is suited for enclosed distribution boards where the door is closed during normal operation. No undervoltage release, no shunt trip, no communication function, and no ground-fault monitoring are built in; this is a plain thermal-magnetic line-protection MCCB. If you need auxiliary contacts or remote tripping, you will add those as external accessories.