What it is and what the ratings mean for your panel
The Siemens SENTRON 3VA1040-3ED36-0JH0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection. It carries 40 A continuously at 40 °C ambient — the same rating holds at 45 °C and 50 °C, then derates to 38.4 A at 55 °C and 36 A at 70 °C. That thermal curve means you can size it for a 40 A feeder in a ventilated panel; in a sealed, hot enclosure you'll need to account for the drop above 50 °C. Interrupting capacity is 75.6 kA at 240 V, 52.5 kA at 415 V, and 32 kA at 440 V — numbers that cover most industrial distribution panels fed by a transformer of moderate size. At 690 V it still holds 7.5 kA, so it can sit on the secondary of a 690 V drive supply without needing an upstream current-limiting fuse for lower fault levels. The breaker ships with a shunt trip (STL) release and an auxiliary switch block configured as 2 auxiliary switches plus 1 trip alarm switch (HQ). That gives you remote tripping capability and status feedback — useful for emergency-off circuits or PLC-based monitoring without adding an external contactor.
Panel fit and mounting
Width is 76.2 mm (3 inches), depth 70 mm, height 130 mm. That 3-inch width is standard for a 3-pole MCCB in the SENTRON 3VA platform — it occupies three 25.4 mm module positions on a DIN rail. The 70 mm depth leaves room for wiring behind the breaker in a 200 mm deep enclosure.