The TM240 release is fixed — no interchangeable trip unit — so the 50 A rating is baked in; if the load grows past 50 A, the breaker itself must be swapped.
Above that it derates linearly: 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, 45 A at 70 °C. In a sealed, uncooled enclosure — say a steel panel in a plant mezzanine — the internal ambient can easily hit 55 °C, so plan for the 49 A ceiling rather than the catalog 50 A. The supplied basic switch is 3VA11506EF320AA0, and the auxiliary switch configuration is two HQ-style switches, so if the panel design calls for remote status indication, those contacts are already there.