What it is and what it does
The Siemens 3VA1140-4EF32-0KC0 is a 3-pole molded case circuit breaker (MCCB) from the SENTRON family, designed for line protection — meaning it sits at the feeder or distribution point to protect cables and busbars against overload and short circuit, not as a motor-protective device. Rated 40 A continuous at 40 °C ambient, it holds that rating up to 50 °C before derating begins — at 55 °C it's 39 A, at 70 °C it's 37 A. That thermal curve matters if the breaker lives in a crowded, warm panel. Breaking 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 both 500 V and 690 V. Those figures tell you it handles high-fault-current scenarios at lower voltages — typical for North American 240/277 V distribution — and still clears moderate faults at 690 V industrial mains. Rated insulation voltage is 800 V, so the breaker's internal clearance and creepage are designed for 690 V systems with margin.
Built-in accessories and panel fit
This variant ships with a shunt trip (STL) for remote tripping and two auxiliary switches (HQ design) for status feedback — both factory-installed, no field retrofit. No undervoltage release, no ground-fault monitoring, no communication module on this order code. Dimensions: 130 mm tall, 76.2 mm wide, 70 mm deep. That 76.2 mm width is exactly 3 inches — a standard MCCB footprint for three-pole breakers in this class. Depth of 70 mm (2.76 in) is shallow enough for most distribution panels without gland-plate interference. Maximum power loss is 10.8 W — useful for thermal budgeting inside a sealed enclosure. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. The breaker is rated for indoor use in conditioned or unconditioned electrical rooms.