What it is and what the ratings mean for fit
The Siemens SENTRON 3VA1140-3EF36-0JA0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous current of 40 A at 40 °C ambient — that's the figure that governs the thermal-magnetic trip curve in a typical 40 °C panel. The TM240 overcurrent release handles the thermal element for overloads and magnetic element for short-circuits; no undervoltage release or communication function is fitted on this variant. The shunt trip release (STL) allows remote tripping via a control voltage, which is what the -3EF36 suffix signals. Breaking capacity is not a single number on this breaker — it varies with system voltage. At 240 V AC it interrupts 75.6 kA, at 415 V AC it drops to 52.5 kA, at 440 V AC to 32 kA, and at 500 V or 690 V AC it holds at 11.9 kA. That means for a 480 V distribution panel the available fault current must be verified against the 11.9 kA rating at 500 V — the 75.6 kA figure at 240 V is only relevant for lower-voltage tap circuits, not the main bus. Rated insulation voltage is 800 V, so the breaker is suitable for 690 V line-to-line systems with margin. The operating temperature range runs from -25 °C to +70 °C, with a slight derating above 55 °C — at 65 °C it carries 38 A, at 70 °C it carries 37 A. The storage range is wider, -40 °C to +80 °C, which is the handling limit, not the running limit.
Panel integration and footprint
The 3VA1140-3EF36-0JA0 measures 130 mm high, 76.2 mm wide, and 70 mm deep — a 3-pole MCCB footprint that fits standard SENTRON mounting bases and busbar systems. The 76.2 mm width (3 inches) is the critical dimension for busbar spacing and multi-pole grouping in a distribution board. Maximum power loss is 10.8 W, which matters for thermal calculations inside a sealed enclosure.