What this MCCB is and what it protects
The Siemens SENTRON 3VA2340-5JQ32-0CH0 is a 3-pole molded case circuit breaker (MCCB) designed for line protection — meaning it sits at the incoming feeder or main distribution point, not on a specific motor or branch circuit. Its full-scale rating is 400 A, with an adjustable trip range from 600 A minimum to 4 000 A maximum, so you set the actual protection threshold to match the downstream load without swapping the breaker frame. Breaking capacity is the headline number that decides whether this breaker survives a fault or welds shut. At 240 V it interrupts 187 kA; at 415 V and 440 V it holds at 121 kA; at 500 V it drops to 75.6 kA; and at 690 V it still clears 7.5 kA. That 187 kA at 240 V is a very high interrupting rating — it handles faults on high-capacity transformer secondaries or large busway drops where available fault current is extreme. Temperature derating matters if this breaker lives in a warm enclosure or near other heat sources. It carries a full 400 A from 40 °C through 50 °C, then steps down: 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. If your panel ambient is above 50 °C, you need to account for that reduction when sizing the feeder.
Mounting and integration into the panel
Physical footprint: 248 mm tall, 138 mm wide, 110 mm deep. That 110 mm depth is the dimension that matters for gland-plate clearance and whether the breaker fits a shallow enclosure without the line-side lugs hitting the back wall. The 138 mm width tells you how many of these fit across a standard 600 mm wide panel — four with some air gap, three comfortably. Max power loss is 98.5 W at full load. That heat has to be vented or conducted out of the enclosure — if you pack several of these in a sealed cabinet, the internal temperature rise will push you into the derating curve above 50 °C. Auxiliary switching is handled by two auxiliary switches plus one trip alarm switch (HQ design). The undervoltage release (UVR) is built in — that means the breaker trips automatically if control voltage drops below the release threshold, which is standard for safety circuits where loss of control power must open the main feeder.
Lifecycle and sourcing posture
Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. The storage limit governs handling and warehousing, not running conditions. The 80 A initial value on the trip unit means the breaker ships with the trip threshold set at 80 A — you adjust it up to the 400 A full-scale during commissioning.