400 A MCCB with ETU340 — what the ratings mean for your panel
The Siemens 3VA2440-6HK32-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C, with the same 400 A rating holding steady all the way up to 70 °C — no derating needed across the typical panel ambient range. That 400 A figure is the continuous current you can count on for the main feeder or a large motor branch circuit. Three-pole design, line-protection configuration, and an ETU340 electronic trip unit. The ETU340 gives you adjustable long-time, short-time, instantaneous, and ground-fault protection curves — a step up from thermal-magnetic trip units for coordinating with downstream breakers in a selective system. Breaking capacity is the headline here: 242 kA at 240 V, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 9 kA at 690 V. That 242 kA at 240 V means it can safely interrupt a fault current of over a quarter-million amps — critical for high-fault installations like transformer secondaries or large industrial services where available fault current is high. At 690 V the 9 kA rating is lower, but that's still adequate for many 690 V motor circuits. Insulation voltage rated 800 V. Max power loss 63.5 W.
Panel fit and integration
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. That 138 mm width is a standard 3-pole MCCB footprint for this current class — it will fit the same mounting pattern as other SENTRON 3VA breakers in the 400 A frame. Depth of 110 mm leaves room for rear-connected bus bars or cable lugs in a typical enclosure. Operating temperature range -25 °C to 70 °C, storage from -40 °C to 80 °C. The storage range covers cold warehouses and hot shipping containers without issue.