What this MCCB delivers — and what it doesn't
The Siemens SENTRON 3VA1140-4EF32-0JA0 is a 3-pole molded case circuit breaker rated for 40 A continuous current (Iu) with a TM240 thermal-magnetic overcurrent release, designed for line protection in distribution panels. Its interrupting capacity is the headline: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 690 V — these are the numbers that govern selectivity studies and SCCR compliance for the downstream panel. The thermal derating is flat at 40 A from 40 °C through 50 °C, then steps down to 38.4 A at 55 °C, 37.6 A at 60 °C, 36.8 A at 65 °C, and 36 A at 70 °C, so in a warm enclosure you lose about 10 % of the rating by 70 °C.
DIN-rail footprint and panel fit
At 70 mm deep, 76.2 mm wide, and 130 mm tall, this breaker fits a standard 3-pole MCCB footprint on the DIN rail. The IP40 front protection means it's fine inside a closed panel but not for washdown areas. No auxiliary contacts, no undervoltage release, no ground-fault monitoring, no communication function — this is a bare line-protection breaker with a shunt trip (STL) as the only auxiliary release, ordered as 3VA9688-0BL32 if you need remote tripping. The 15,000-cycle mechanical endurance is typical for this class; expect it to outlast the panel's service life in most fixed installations.