What this MCCB is and what it does
The Siemens SENTRON 3VA2340-5JQ32-0AC0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection — meaning it sits at the incoming feed of a distribution panel or as a main disconnect for a sub-panel, not downstream protecting a specific motor or branch circuit. Its job is to clear faults fast enough that upstream gear doesn't trip. Rated 400 A continuous at 40 °C ambient, it holds that rating all the way to 50 °C — useful if the panel runs warm. Above that, it derates: 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. If your enclosure hits 70 °C, you lose 100 A of headroom; plan the thermal budget accordingly. Breaking capacity is the number that decides whether this breaker survives a dead short. At 240 V it clears 187 kA — that's utility-grade fault current. At 415 V and 440 V it's still 121 kA. At 500 V it drops to 75.6 kA, and at 690 V it's 7.5 kA. If your system runs 690 V, this is not the breaker for that bus; the 7.5 kA rating is too low for most industrial 690 V applications.
Physical fit and panel integration
Dimensions: 248 mm tall, 138 mm wide, 110 mm deep. The 110 mm depth fits shallow enclosures with wiring room. Maximum power dissipation is 96 W at full rated load. That's the heat you need to vent. In a sealed enclosure with other heat sources, factor this into the thermal calculation — 96 W is non-trivial for a small cabinet.
Trip unit and adjustability
The electronic trip unit is adjustable between 600 A and 4 000 A — that's the short-circuit and ground-fault pickup range, not the continuous current rating. The continuous rating is fixed at 400 A (the frame size). The trip indicator is not present on this variant, so there's no local mechanical flag showing the breaker tripped on fault vs. manual open. No undervoltage release or voltage-triggered shunt trip fitted. For remote trip, use the basic switch variant or add an external release module.
Auxiliary contacts and communication
Comes with two auxiliary switches (HQ type) for status feedback — one normally open, one normally closed, or both NO/NC depending on the HQ configuration. These are wired back to a PLC or status lamp to indicate open/closed state of the breaker. Communication function is present for remote monitoring and trip data.