What it is and what it does in the panel
The Siemens SENTRON 3VA1140-3EF36-0DC0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous 40 A at 40 °C with a 75.6 kA interrupting capacity at 240 V AC. That breaking capacity drops to 52.5 kA at 415 V, 32 kA at 440 V, and 11.9 kA at 500 V and 690 V — so the available fault current at the panelboard determines which voltage tap you land it on. The 800 V rated insulation voltage (Ui) means it's built for 480/277 V and 600 V systems with headroom. This breaker includes an undervoltage release (UVR) as standard — when line voltage drops below the release threshold, it trips the mechanism, which is useful for preventing motor restart after a sag or for coordinated emergency-stop circuits. The auxiliary switch configuration is two HQ auxiliary switches, giving you status feedback for the PLC or annunciator without an add-on module.
Thermal derating and power loss — real panel conditions
The 40 A rating holds solid from 40 °C up to 50 °C. At 55 °C it derates to 39 A, at 65 °C to 38 A, and at 70 °C to 37 A. If your panel ambient runs above 50 °C — common in a non-ventilated enclosure near a molding machine or drive cabinet — you need to account for that 1–3 A drop. Maximum power loss is 13.3 W, which is modest for a 40 A frame and won't drive much internal temperature rise in a standard enclosure, but it's still a factor if you're packing multiple breakers in a small dead-front panel.
Dimensions and panel fit
The breaker measures 130 mm high, 76.2 mm wide (3 in), and 70 mm deep (2.76 in). That 70 mm depth is the dimension from the mounting surface to the front of the breaker — important when you're checking clearance to the enclosure door or a dead-front shield. The 76.2 mm width is a standard 3-inch footprint for a 3-pole MCCB in this class, so it drops into a panel cutout or DIN-rail adapter without surprises.
Operating environment and storage
Operates from -25 °C to 70 °C ambient. Storage range is wider: -40 °C to 80 °C, which covers unheated warehouses and shipping containers. The operating minimum of -25 °C means it's fine for outdoor enclosures in most temperate climates, but not for deep-freeze or arctic installations without supplementary heating.