That 250 A holds from 40 °C through 50 °C ambient — above that it derates linearly to 213 A at 70 °C, so the thermal environment in your enclosure directly governs whether this frame covers your load without nuisance tripping. Breaking capacity is the real selector here: 187 kA at 240 V, 121 kA at 415/440 V, 79 kA at 500 V, and 5.1 kA at 690 V. The line protection version means it's configured for feeder protection rather than motor or generator duty.
The 5SQ series is the older frame; the 3VA2 is the current platform. Check the mounting hole pattern against your existing panel layout before committing the order.
In a washdown or outdoor enclosure, the breaker itself needs a sealed cabinet; the IP40 rating covers the operator interface only. Maximum power loss is 48 W.