What this MCCB carries — and what it means for your panel
The Siemens SENTRON 3VA2340-5JP32-0DL0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, with a continuous current Iu of 400 A. Its breaking capacity hits 187 kA at 240 V and 121 kA at 415 V — figures that tell you it can clear a high-fault bolted short without cascading upstream. That 187 kA rating at 240 V is the one that matters when this breaker sits near a large transformer secondary or a capacitor bank; the 121 kA at 415 V covers the common industrial distribution voltage. At 690 V the capacity drops to 17 kA, so if your system runs at 690 V, verify the available fault current before specifying. The ETU550 electronic trip unit gives you adjustable long-time, short-time, instantaneous, and ground-fault protection curves. That means you can coordinate this breaker downstream of a main and upstream of feeders without guessing — the ETU550 lets you set the pickup and delay bands to match the load profile. The undervoltage release is built in, so if the control voltage drops, the breaker opens automatically — a standard requirement for safety circuits in conveyor and machine-tool panels. Physical footprint: 248 mm high, 138 mm wide, 110 mm deep. That 138 mm width is the 3-pole frame size.
Thermal derating — the real current rating depends on your cabinet temperature
The 400 A rating holds up to 50 °C ambient. Above that, you must derate: 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, a non-ventilated enclosure near a furnace line — the 300 A at 70 °C figure is the one to use for your load calculation. The maximum operating ambient is 70 °C; storage range is -40 °C to 80 °C.
Auxiliary contacts and communication
The auxiliary contact block is configured as 2 auxiliary switches + 1 trip alarm switch + 1 electrical alarm switch HQ. That gives you two NO/NC pairs for status feedback to a PLC, plus a dedicated trip alarm contact that changes state only on a fault trip — useful for differentiating a manual open from an overcurrent event. The communication function means this breaker can integrate with a higher-level monitoring system, though the specific protocol is not detailed here. Power loss at rated current is 98.5 W maximum — account for that heat in your enclosure thermal calculation.