What it is and what it does
The Siemens 3VA1140-3EF32-0DA0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels. It carries a 40 A continuous rating at 40 °C and delivers a 75.6 kA interrupting capacity at 240 V — enough to clear high-fault scenarios downstream of a transformer without upstream coordination headaches. Rated insulation voltage is 800 V. The 3-pole construction with a TM240 thermal-magnetic trip unit provides fixed-curve overcurrent protection.
Breaking capacity across voltages
Interrupting rating drops as voltage rises: 75.6 kA at 240 V, 52.5 kA at 415 V, 32 kA at 440 V, and 11.9 kA at both 500 V and 690 V. That 11.9 kA at 690 V is the weak point — if your panel's available fault current exceeds that at 690 V, this breaker won't clear it safely. For most 480 V industrial services the 32 kA at 440 V is the relevant figure.
Undervoltage release and thermal derating
This variant ships with an undervoltage release (UVR) — the auxiliary release type is specifically an undervoltage release. That means the breaker trips if control voltage drops below a threshold, useful for preventing motor restart after a brownout. The UVR is factory-installed; no field retrofit needed. Thermal derating is minimal up to 50 °C (still 40 A), then drops to 39 A at 55 °C and 60 °C, 38 A at 65 °C, and 37 A at 70 °C. If your panel ambient runs above 50 °C, plan for that 3 A loss at the top end.
Panel fit and dimensions
Dimensions: 130 mm height, 76.2 mm width, 70 mm depth. The 3-pole width (76.2 mm) is standard for this frame size — it occupies three 25 mm module spaces on a DIN rail. Depth of 70 mm leaves room for wiring gutters in a typical 200 mm deep enclosure.