The Siemens SENTRON 3VA2040-5HN42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for 40 A continuous current across the full ambient range of 40 °C to 70 °C — no derating needed up to that ceiling.
This MCCB interrupts 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 3 kA at 690 V. The 187 kA figure at 240 V tells you it can handle a bolted fault on a large transformer secondary without the breaker failing — that's the kind of SCCR you need for a main breaker in a 480 V / 277 V panel fed by a 1000 kVA transformer. The drop to 3 kA at 690 V is typical for a 40 A frame; at that voltage the arc energy is higher, so the interrupting limit drops. For most industrial distribution at 480 V, the 121 kA rating gives you plenty of headroom.
It's a panel-mount MCCB — no DIN-rail clip, so plan for screw-mounting on a backplate or in a distribution cabinet. The 4-pole design handles three-phase plus neutral, common for 480Y/277 V or 208Y/120 V systems where you need to switch the neutral.