What this 3VA2340-5KQ32-0LC0 is and what it does
The Siemens SENTRON 3VA2340-5KQ32-0LC0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous current of 400 A at 40 °C. It's built to handle serious fault current — 187 kA interrupting capacity at 240 V and 121 kA at 415 V — so it can sit upstream in a distribution panel where the available fault current is high. The 3VA frame is the current SENTRON generation, and this variant includes an undervoltage release (UNI universal trigger) plus two HQ auxiliary switches for status feedback. It also has a communication function, meaning it can talk to a higher-level monitoring or control system.
What the ratings mean for your panel
The 400 A rating holds steady from 40 °C up to 50 °C, then derates: 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. If your panel runs hot — say, in a non-conditioned electrical room near a furnace or in a steel mill — that 70 °C derate to 300 A is the number you design to, not the 400 A sticker. The interrupting curve drops fast at higher voltages: 75.6 kA at 500 V and only 7.5 kA at 690 V. At 690 V this breaker is still useful for a lightly-faulted industrial system, but it's not your main service entrance breaker at that voltage. The 3-pole construction fits standard three-phase distribution.
Physical fit and integration
The breaker measures 248 mm high, 138 mm wide, and 110 mm deep. That 110 mm depth (4.33 inches) is the dimension you check against the enclosure door clearance and bus bar reach. The 138 mm width (5.43 inches) determines the DIN-rail or mounting-plate spacing for a 3-pole MCCB. It ships with two HQ auxiliary switches and a universal trigger (UNI) undervoltage release already integrated — no separate field-assembly of those accessories. The communication function is onboard, so you only need to wire the bus connection.
Environmental and compliance
Operating temperature range is -25 °C to 70 °C; storage goes from -40 °C to 80 °C. Max power loss is 98.5 W at rated load — that's heat that stays in the enclosure, so factor it into your thermal budget if the panel is sealed. The breaker includes a voltage trigger (undervoltage release) and a communication function, both of which require their own wiring and coordination with the control system.