What it is and what it does
The Siemens 3VA2340-6HN32-0BH0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection, with a continuous current rating of 400 A at 40 °C and a 3-pole configuration. It carries a maximum breaking capacity of 242 kA at 240 V AC, dropping to 187 kA at 415 V and 121 kA at 500 V — sufficient for high-fault industrial distribution panels where upstream transformer capacity is large. The breaker is fitted with an undervoltage release (UVR) and two auxiliary switches plus one trip alarm switch (HQ), so it can signal its status to a PLC or annunciator panel without separate interface relays.
Current derating and thermal management
At 40 °C the breaker carries its full 400 A; derating begins above 55 °C, reaching 385 A at 55 °C and 340 A at 70 °C. Maximum power loss is 98.5 W — a figure to consider when calculating enclosure heat rise, especially in a sealed panel with multiple breakers. The operating temperature range is -25 °C to 70 °C, with storage from -40 °C to 80 °C. Panel placement should avoid direct adjacency to high-heat sources (transformers, VFDs) to stay within the derating curve.