320 A MCCB with 154 kA breaking capacity — what that means on the line
The Siemens SENTRON 3VA1332-6MH32-0AC0 is a 3-pole molded case circuit breaker rated for 320 A continuous, with a TM120M thermal-magnetic overcurrent release. That 320 A holds all the way up to 50 °C ambient; at 55 °C it derates to 313 A, and at 70 °C it's still good for 292 A. The interrupting rating at 415 V is 154 kA — that's the fault current it can safely clear without welding contacts or rupturing the case. Out here in the grease, that means this MCCB will survive a hard bolted fault on a 400 V distribution bus without taking the whole panel with it.
Where this MCCB fits in the panel
At 110 mm deep, 138 mm wide, and 248 mm tall, this breaker lands in a standard SENTRON 3VA frame size. The 3-pole layout and the TM120M release mean it's set up for motor branch circuits or feeder protection where you need a fixed thermal curve and magnetic short-circuit pickup. The auxiliary switch design carries two HQ form-C contacts — handy for a remote trip-indication circuit without adding a separate accessory. No undervoltage release and no communication module on this variant, so if the BOM calls for those, you're looking at a different order code in the 3VA family.
Breaking capacity across voltage levels
The interrupting rating drops as voltage climbs: 220 kA at 240 V, 154 kA at both 415 V and 440 V, 121 kA at 500 V, and 17 kA at 690 V. That 17 kA at 690 V is the number to watch if you're on a 690 V IT or corner-grounded delta system — it's still a healthy rating, but it's a fraction of the low-voltage capability. The insulation voltage is rated 800 V, so the breaker itself is built for that 690 V service.