Line-protection MCCB with ETU350 — what the ratings mean for your panel
The Siemens 3VA2225-6HN32-0HD0 is a SENTRON 3VA2 molded case circuit breaker (MCCB) configured for line protection — meaning it sits upstream protecting a feeder or distribution bus, not a specific motor or load group. Rated continuous current Iu is 250 A, and it carries a 3-pole construction with an ETU350 electronic trip unit. The ETU350 gives you adjustable time-current curves (L, S, I, G) via DIP switches or rotary dials on the front face, so you can coordinate selectively with downstream breakers without changing the trip unit itself. Breaking capacity at 240 V is 242 kA — that is the maximum fault current it can safely interrupt at that voltage without welding contacts or rupturing the case; at 690 V the same breaker derates to 4.5 kA, so verify your system's available fault current at the point of installation.
Thermal derating and enclosure fit
The 250 A rating holds flat from 40 °C to 50 °C ambient; above that it begins to taper — 241 A at 55 °C, 232 A at 60 °C, 222 A at 65 °C, and 213 A at 70 °C. If the breaker lives inside a sealed, uncooled enclosure near other heat sources, you need to size the load or the breaker for the derated value, not the nameplate 250 A. Dimensions are 181 mm high × 105 mm wide × 86 mm deep — a standard 3VA2 frame that fits the SENTRON mounting footprint. Front-face IP40 means it is protected against tools and wires >1 mm but not against water ingress; the enclosure itself should provide the IP rating for the environment.
Breaking capacity across voltages — selectivity planning
The 3VA2225-6HN32-0HD0 delivers 242 kA at 240 V, 187 kA at both 415 V and 440 V, 121 kA at 500 V, and 4.5 kA at 690 V. These are the maximum interrupting ratings at each voltage level; they define the upper bound for fault current the breaker can clear while maintaining its integrity. When designing selective coordination, use the rating at your system voltage — not the highest number on the datasheet — because a 690 V fault sees only 4.5 kA of interrupting capability, which may be lower than the available fault current in a 690 V distribution panel.