What it is and what it does
The Siemens SENTRON 3VA1040-3ED36-0CH0 is a 3-pole molded case circuit breaker (MCCB) rated at 40 A continuous at 40 °C ambient, with a breaking capacity of 75.6 kA at 240 V AC and 52.5 kA at 415 V AC. It's a line-protection device — the standard job is protecting cables and busbars from short-circuit and overload in a distribution panel. The 40 A rating holds steady from 40 °C up to 50 °C, then derates to 38.4 A at 55 °C and 36 A at 70 °C — so if the panel runs hot, the breaker still carries the load without nuisance tripping. It ships with an undervoltage release (UVR) fitted — that's the coil that drops the breaker if control power is lost, common in emergency-stop chains and safety circuits.
Panel fit and footprint
Footprint is 76.2 mm wide by 130 mm tall by 70 mm deep — a standard 3-pole MCCB form factor that drops into most SENTRON panelboards and DIN-rail adapters without re-drilling. The auxiliary switch block is configured as 2 auxiliary switches plus 1 trip alarm switch (HQ type) — enough for remote status feedback to a PLC or annunciator.
Breaking capacity — what the numbers mean
The 75.6 kA at 240 V and 52.5 kA at 415 V are the interrupting ratings — the maximum fault current this breaker can safely clear at those voltages. At 440 V it's 32 kA, and at 500 V and 690 V it drops to 7.5 kA. That's enough for most industrial distribution boards fed by a transformer under 2 MVA; if your available fault current exceeds 75.6 kA at 240 V, you need a current-limiting upstream device. Insulation voltage is rated 800 V, so the internal clearances are designed for 690 V systems with margin.