What the ratings mean for fit
The Siemens 3VA1140-4EE42-0AA0 is a SENTRON 4-pole molded case circuit breaker rated for 40 A continuous current with a TM220 thermal-magnetic release — that TM designation means it uses a bimetal element for overload protection and a magnetic coil for short-circuit response, no electronics to drift or fail on a hot panel. Breaking capacity runs 121 kA at 240 V AC, 76 kA at 415 V, 53 kA at 440 V, and holds 11.9 kA all the way out to 690 V; that curve tells you it's sized for high-fault industrial distribution where available fault current varies by transformer tap and voltage class. The 800 V rated insulation voltage (Ui) means the internal clearances and creepage are designed for 690 V line-to-line systems with margin. Temperature derating is honest: it carries the full 40 A from 40 °C through 50 °C, drops to 39 A at 55–60 °C, then 38 A at 65 °C and 37 A at 70 °C. That means in a sealed, uncooled enclosure near other heat sources you lose about 7.5 % of capacity at the top end — plan your load accordingly rather than assuming nameplate current holds at every ambient.
Panel integration and footprint
Mechanical endurance is rated at 20,000 operations. Maximum power loss of 10.8 W at rated current matters for thermal management in a densely packed panel — that's the heat you need to vent. Operating temperature range spans -40 °C to 70 °C, storage from -40 °C to 80 °C, so it handles cold storage and hot running without issue.