400 A MCCB with 242 kA interrupting capacity — what the ratings mean for your panel
The Siemens 3VA2440-6HL32-0HA0 is a SENTRON molded case circuit breaker (MCCB) rated for continuous current Iu of 400 A at 40 °C, with a rated insulation voltage Ui of 800 V. The headline breaking capacity hits 242 kA at 240 V — that is the short-circuit current it can safely interrupt without welding contacts or rupturing the case. At 415 V and 440 V the rating holds at 187 kA, dropping to 121 kA at 500 V and 40 kA at 690 V. For a 400 A frame, these numbers place it in the high-interrupting category, suited for large transformer secondaries or bus-tie applications where fault current can exceed 100 kA. Thermal derating is modest: the breaker carries the full 400 A up to 50 °C ambient, then drops to 384 A at 55 °C, 376 A at 60 °C, 368 A at 65 °C, and 360 A at 70 °C. That means in a warm enclosure — say a non-ventilated panel near a furnace line — you still have headroom at 360 A before the thermal-magnetic trip curve shifts. The maximum power loss is 63.5 W, which matters for enclosure heat load calculations.
Trip unit, release, and auxiliary options — what is and is not inside
This variant ships with an ETU320 overcurrent release and a shunt trip (STL) auxiliary release. There is no undervoltage release, no ground-fault monitoring, no communication function, no phase-failure detection, and no auxiliary contact block. The shunt trip is factory-fitted as the integrated auxiliary trip (order code 3VA9688-0BL30). The supplied basic switch is 3VA2440-6HL32-0AA0. If your application requires undervoltage protection or remote status feedback, you will need a different suffix or field-installable accessory. The breaker has a voltage-trigger function (yes) but no trip indicator. Mechanical endurance is rated at 15,000 operations — typical for a 400 A frame used in infrequent switching (main disconnect or backup, not motor-start duty). Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.
Physical fit and panel integration
Dimensions are 248 mm high, 138 mm wide, and 110 mm deep. The 3-pole frame mounts on a DIN rail or can be screw-fixed to a backplate. The 110 mm depth is shallower than many 400 A MCCBs, which helps in shallow enclosures. Panel builders should verify the lug or bus-bar connection clearance on the line and load side — the 138 mm width is standard for a 400 A SENTRON frame, so existing bus-bar kits for the 3VA2 series should align.