What this 4-pole 400 A MCCB carries
The Siemens SENTRON 3VA2340-5JQ42-0CH0 is a 4-pole molded case circuit breaker (MCCB) on a 400 A frame, designed for line protection in distribution panels and motor control centers. Its interrupting capacity reaches 187 kA at 240 VAC, 121 kA at 415/440 VAC, 75.6 kA at 500 VAC, and 7.5 kA at 690 VAC — so at typical 400 V class industrial voltages it clears faults well above the 50–65 kA most service-entrance breakers are rated for, meaning it can be used as a main or large feeder breaker without cascading concerns. The thermal-magnetic trip unit is adjustable from 600 A minimum to 4000 A maximum, with a factory-default full-scale value of 400 A. That wide adjustment range lets one frame size cover multiple load banks — set it at 600 A for a 250 kW motor feeder or dial it up to 4000 A for a transformer secondary or bus riser.
Thermal derating and panel integration
At 40 °C, 45 °C, and 50 °C ambient the breaker carries the full 400 A continuously. Above 50 °C it derates linearly: 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. If your panel ambient runs above 50 °C — common in a packed MCC lineup or outdoor enclosure in direct sun — you need to account for that 25 A per 5 °C drop. The breaker dissipates 98.5 W maximum at rated load, so ventilation or spacing in the enclosure matters. Physical footprint is 248 mm high, 184 mm wide, 110 mm deep — a 4-pole frame that fits standard SENTRON mounting plates and busbar systems. The depth is shallow enough for 300 mm deep enclosures with wiring gutters.
Built-in accessories and communication
This variant ships with an undervoltage release (UVR) and two auxiliary switches plus one trip alarm switch (HQ configuration). The UVR drops the breaker if control voltage falls below its dropout threshold — standard practice for emergency-stop circuits and undervoltage protection on motor feeders. Communication function is onboard, so it can integrate with a BMS or SCADA system for remote trip indication and load monitoring. The basic switch version is 3VA2340-5JQ42-0AA0 — this -0CH0 suffix adds the UVR and the HQ auxiliary switch complement. If your BOM already specifies the -0AA0 and you need undervoltage protection, this is the drop-in upgrade without changing mounting or bus connections.