What this MCCB carries on a shipboard switchboard
Its breaking capacity reaches 75.6 kA at 240 V AC and 52.5 kA at 415 V AC, which means it can safely interrupt fault currents up to those levels without cascading upstream — essential for selectivity studies on a vessel's main switchboard or emergency distribution board.
At 440 V AC the interrupting rating is 32 kA, dropping to 11.9 kA at 500 V and 690 V AC. That voltage-dependent curve is typical for MCCBs, but critical when the breaker is applied near the transformer secondary on a 480 V or 690 V shipboard system — the available fault current must be coordinated with the breaker's rating at that specific voltage. The thermal-magnetic TM220 release holds 16 A from 40 °C through 55 °C, then derates to 15 A at 60 °C through 70 °C. In a hot machinery space or unventilated panel, that 1 A drop can mean the difference between nuisance tripping and a stable feed.