What it is and what it does
The Siemens 3VA2340-5JQ32-0CA0 is a SENTRON 3VA2 molded case circuit breaker (MCCB) designed for line protection in distribution panels. It's a 3-pole unit rated 400 A continuous at 40 °C, with a full-scale adjustment range from 80 A up to 400 A — meaning you dial in the actual trip threshold to match the downstream load, not just the frame size. Breaking capacity is the headline: 187 kA at 240 V AC, 121 kA at 415/440 V, 75.6 kA at 500 V, and 7.5 kA at 690 V. That 187 kA figure at 240 V tells you it handles high-fault utility feeds or transformer secondaries without needing a current-limiting fuse upstream — a real advantage in panel coordination studies. It ships with an undervoltage release (UVR) fitted and a communication function onboard — the UVR trips the breaker if control voltage drops, standard for emergency-stop or undervoltage protection schemes. The comms port means it can talk to a BMS or PLC for remote trip indication and load monitoring, though the exact protocol isn't specified here.
Thermal derating and real-world current
The 400 A rating holds flat from 40 °C through 50 °C ambient — no derate needed in a typical 40 °C panel. At 55 °C it drops to 375 A, at 60 °C to 350 A, at 65 °C to 325 A, and at 70 °C to 300 A. If your enclosure runs hot (say, a non-ventilated outdoor cabinet in summer), you need to account for that 25 A per 5 °C step above 50 °C. Maximum power loss is 98.5 W at rated current — that's the heat the breaker dumps into the panel. For a multi-breaker lineup, that adds up; factor it into your enclosure ventilation or forced-air cooling budget.
Physical fit and mounting
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. That 138 mm width is the standard 3-pole MCCB footprint for this frame size — it fits existing SENTRON 3VA2 panel cutouts and busbar arrangements without modification. The 248 mm height and 110 mm depth are within the envelope for most distribution boards and motor control centers.
Approvals and compliance
As a Siemens SENTRON product, this MCCB carries the expected certifications for industrial distribution: IEC 60947-2 (the global standard for MCCBs), likely UL 489 listing for North American panels, and CE marking for European installations. RoHS and REACH compliance documentation is standard from Siemens for this active series.