The Siemens 3VA1040-4ED32-0BC0 is a 3-pole SENTRON molded case circuit breaker (MCCB) rated for 40 A continuous current at 40 °C ambient, with a TM210 thermal-magnetic overcurrent release.
Breaking capacity — the real number to watch
This breaker punches hard on fault interruption: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and still 11.9 kA at 690 V. For a 40 A frame, those are high-interrupting ratings — it'll clear a bolted fault on a large transformer secondary without the upstream fuse having to think about it. The 415 V figure is the one most panel builders will size against for 400 V distribution; 75.6 kA gives plenty of SCCR headroom for a typical industrial main lug.
At 55 °C it's 38.4 A; at 70 °C it's 36 A. That's a shallow derating curve — you lose only 4 A across a 30 °C rise, which means it runs cool in a crowded panel. The TM210 release is thermal-magnetic, so the thermal element tracks ambient; no need to manually adjust for seasonal temperature swings in a non-climate-controlled enclosure.