What the ratings mean for fit
The Siemens 3VA2010-6HN42-0AA0 is a 4-pole SENTRON molded case circuit breaker (MCCB) rated at a continuous 100 A across its full ambient range from 40 °C to 70 °C — no derating needed up to that ceiling. That 100 A holds steady even at 70 °C, which is unusual; most breakers start dropping current above 40 °C. The ETU350 electronic trip unit gives you adjustable N-conductor protection (OFF, 50%, 100%) and line protection, but there's no voltage trip, no communication function, and no ground-fault monitoring built in. If you need those, this isn't the variant.
Interrupting capacity — the real selector
The headline number is 242 kA at 240 V, dropping to 187 kA at 415 V and 440 V, then 121 kA at 500 V, and finally 3 kA at 690 V. That 242 kA at 240 V is a high-interrupting-capacity frame — it'll clear a massive fault without cascading upstream, which matters for transformer secondaries or large motor control centers. At 690 V the 3 kA figure is low; if your system runs at that voltage with high available fault current, this breaker won't coordinate. The 800 V rated insulation voltage (Ui) confirms the insulation system can handle the voltage, but the breaking capacity at 690 V is the binding constraint.
Physical fit and panel integration
Dimensions: 181 mm high, 140 mm wide, 86 mm deep. That's a 4-pole MCCB in a standard SENTRON 3VA frame — it mounts on a DIN rail or directly to a backplate via the screw terminals. The IP40 front protection means it's fine in a clean indoor panel; no washdown rating. Power loss is 13.5 W maximum, so factor that into your enclosure thermal budget if you're packing several in a small cabinet.