What this 40 A MCCB does on the line
The Siemens 3VA1140-4EF32-0CH0 is a SENTRON molded case circuit breaker sized for 40 A continuous duty at 40 °C ambient, with a TM240 thermal-magnetic overcurrent release that handles overload and short-circuit protection in a single package. Its 121 kA interrupting rating at 240 V means it can clear a fault at that level without welding contacts or rupturing the case — essential for high-fault panels near large transformers or service entrances. At 415 V the rating drops to 75.6 kA, and at 690 V to 11.9 kA, so the SCCR coordination study needs to check the actual line voltage before committing this breaker to a branch. The 3-pole design with undervoltage release (UVR) is configured for line protection — not motor or generator protection — so it trips on overcurrent and undervoltage conditions. The UVR coil drops the breaker when supply voltage falls below a threshold, which is useful for preventing automatic restart after a brownout on machinery that requires supervised restart. No communication function, no phase failure detection, and no ground fault monitoring are built in; those would need external modules or a different variant.
Thermal derating and panel fit
The 40 A rating holds flat from 40 °C through 50 °C ambient. Above that it derates: 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 the panel ambient runs above 50 °C — say a sealed enclosure near a furnace line — the continuous load must be trimmed accordingly. The operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. Dimensions are 130 mm height, 76.2 mm width, 70 mm depth. The width is a standard 3-pole MCCB footprint for DIN-rail or screw-mount panels. IP40 on the front means it's protected against tools and wires >1 mm but not against water ingress — keep it inside a rated enclosure. The auxiliary contact configuration is 2 auxiliary switches plus 1 trip alarm switch (HQ version), which gives three separate signal paths for status feedback to a PLC or annunciator panel.