400 A MCCB with 242 kA interrupting rating — what the numbers mean for your panel
The Siemens SENTRON 3VA2340-6HL32-0JH0 is a 3-pole molded case circuit breaker rated for 400 A continuous current across the 40 °C to 50 °C ambient range — no derating needed in a standard 40 °C panel environment. At 240 V AC it interrupts fault currents up to 242 kA, which puts it in the high-interrupting category for large industrial service entrances or distribution sections where available fault current is severe. At 415 V and 440 V it still holds 187 kA, dropping to 121 kA at 500 V and 7.5 kA at 690 V — the steep roll-off above 500 V means this breaker is primarily sized for 240–500 V distribution, not 690 V motor circuits. The breaker is configured for line protection (not motor or generator protection) and ships with a shunt trip release (STL) plus two auxiliary switches and one trip alarm switch HQ. The basic switch assembly is order code 3VA2340-6HL32-0AA0 — the -0JH0 suffix adds the shunt trip and auxiliary contact block. No undervoltage release, no ground-fault monitoring, no communication module on this variant. Maximum power loss is 96 W — plan for that heat rejection inside the enclosure if the breaker is loaded near its 400 A rating continuously. The operating temperature range is -25 °C to 70 °C, with storage from -40 °C to 80 °C.
Thermal derating curve — where the 400 A rating holds and where it drops
This breaker carries its full 400 A rating from 40 °C through 50 °C ambient. At 55 °C it derates to 385 A, at 60 °C to 370 A, at 65 °C to 355 A, and at 70 °C to 340 A. If the panel ambient runs above 50 °C, the continuous load must be reduced accordingly — no way around it. The trip indicator and voltage trigger are present, so the breaker reports its state locally.
Physical fit — panel integration notes
Dimensions are 248 mm high, 138 mm wide, 110 mm deep — a standard MCCB footprint for this current class. The 138 mm width across three poles means a 4-pole version of the same frame would be roughly 184 mm. Mounting is via the rear panel or DIN rail adapter (not included in this variant). Allow the 96 W dissipation in the thermal budget; forced ventilation may be needed if the enclosure is sealed and loaded continuously.