What the ratings mean for your panel
The Siemens SENTRON 3VA2340-6JQ32-0AA0 is a 3-pole molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C, with an adjustable thermal-magnetic trip range from 600 A to 4 000 A — meaning you set the instantaneous pickup to match your feeder or main breaker coordination study, not a fixed threshold. Breaking capacity is 242 kA at 240 VAC, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 7.5 kA at 690 V — so at typical 480 V distribution levels it clears fault currents well above what most service-entrance gear can deliver, and the 690 V rating covers 600 V class systems with a comfortable margin. Rated insulation voltage is 800 V, which means the breaker's internal clearances and creepage are designed for 600 V class switchgear without derating. It includes a communication function (likely PROFIBUS or PROFINET via a plug-in module) and summation-current ground-fault monitoring on the line conductors — useful for a main breaker that needs to report status and trip events to a BMS or SCADA system.
Thermal derating and power loss
The breaker carries 400 A continuously up to 50 °C ambient, then derates to 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C — so in a hot switchroom or a panel with dense heat sources, expect to downrate the main bus by 25% at the upper end. Maximum power loss is 96 W at rated current — a modest figure for a 400 A frame, but enough to factor into enclosure ventilation if the breaker is in a sealed cabinet with other heat sources. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C — the storage limit matters for spares kept in unheated warehouses or site containers.
Physical fit and panel integration
Dimensions are 248 mm high, 138 mm wide, 110 mm deep — a standard 3-pole MCCB footprint that fits most Siemens SENTRON mounting plates and busbar systems without adapter brackets. The 138 mm width is the same as the 3VA2 frame family, so if you are replacing a 3VA2225-5JQ32-0AK0 (225 A frame) with this 400 A unit, the panel cutout and busbar spacing are identical — no rewiring or re-drilling needed.
Lifecycle and sourcing
For a BOM freeze or a panel that was specified around the 3VA2225-5JQ32-0AK0, the 3VA2340-6JQ32-0AA0 is a direct frame-size upgrade with the same width and mounting pattern, but verify the trip curve coordination if the downstream gear was sized for the 225 A breaker.