MCCB for line protection with high interrupting capacity
The Siemens 3VA1140-6EF32-0KA0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection — meaning it guards feeder cables and distribution buswork against overloads and short circuits, not motor loads directly. Its 40 A rating at 40 °C is the continuous current it can carry without tripping; the TM240 thermal-magnetic release provides fixed thermal and magnetic trip elements, so no adjustment dials on the front. The 3-pole construction suits three-phase systems up to 800 V rated insulation voltage. What sets this MCCB apart is the interrupting capacity: 220 kA at 240 V AC, 154 kA at 415 V, 121 kA at 440 V, and still 17 kA at 690 V. That 220 kA figure at 240 V means it can safely clear a fault current of that magnitude — typical for high-capacity transformer secondaries or large bus risers in industrial plants. The shunt trip (STL) auxiliary release allows remote tripping from an emergency stop or supervisory system; no undervoltage release is fitted, and there is no communication module — this is a standalone breaker, not a networked one.
Thermal derating and panel fit
The breaker carries 40 A continuously from 40 °C through 50 °C (–), then derates to 39 A at 55 °C and 60 °C, 38 A at 65 °C, and 37 A at 70 °C. That is a mild derating curve — only 3 A lost from 40 °C to 70 °C — so it holds its rating well in warm enclosures. The dimensions are 130 mm height, 76.2 mm width, and 70 mm depth; the 70 mm depth is the front-to-back dimension, which matters when fitting into a shallow gland plate or a compact panel. Maximum power loss is 10.8 W at full load, which adds to the enclosure heat budget.